REAL TIME TRACE DETECTION OF ELEMENTAL MERCURY AND ITS COMPOUNDS Robert B. Barat New Jersey lnstitute of Technology, Department of Chemical Engineering, Chemistry, and Environmental Science, Newark, NJ 07102 INTRODUCTION Emission of mercury vapor from combustion and other processes is now considered to be a major environmental issue [ Von Burg and Greenwood, 1991]. It can be emitted directly to the air in its highly volatile elemental form. In addition, mercury compounds [ e. g. HgCl2, Hg( CH3) 2] are quite volatile, and have been detected in incinerator effluent and the biosphere.

The present research addresses the need to develop real time stack monitoring of emissions of Hg and its compounds. Such technology will enable combustion facilities to identify peak emission events and take corrective WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 41 action. It will replace the current uncertainty in emission estimations based on feed mercury content. Realistic emission inventory will enable regulatory agencies to better assess health risks associated with future siting of waste incinerators.

To be applicable to a wide range of applications, an instrument should be capable of detecting Hg in the range of 1 5000 µ g/ m3, with an ultimate sensitivity limit on the order of 0.1 µ g/ m3 ( ca. 10 pptv). Current best technology for mercury detection uses a collection / concentration step followed by off line analysis using atomic absorption, atomic fluorescence, or plasma emission spectroscopy [ Baeyens, 1992]. None of these three detection methods in their commercially available configurations are suitable for real time monitoring of elemental mercury.

The detection concept for elemental mercury involves Doppler shifted resonant atomic fluorescence excited by a UV laser or a low pressure mercury lamp. The Doppler shifted fluorescence will be separated from the unshifted background signal by use of a mercury vapor filter precisely matched to the spectral linewidth of the source. The detection concept for compounded mercury will use the photofragment fluorescence ( PFF) excited by deep UV light. Examination of the fluorescence spectrum will permit identification of the original mercury compounds. Photo fragment fluorescence has been successfully applied for the gas phase analysis of HgCl2, Hg( CH3) Cl, and HgI2 ( Poulos and Barat, 1997).

APPROACH  ELEMENTAL HG Atomic Fluorescence Spectroscopy ( AFS) is a highly sensitive spectroscopic marker for elemental Hg detection. Current AFS instruments use a cold vapor trap for collection/ concentration of the air sample followed by purging and excitation with an atomic vapor mercury lamp ( 253.7 nm) and measurement of the resonant fluorescence ( at the same wavelength). Sensitivity is limited by the elastically scattered light from the exciting source. In the case of 253.7 nm Hg fluorescence, this limitation is problematic because the fluorescence signal is already reduced due to quenching by air.

The technique under study, shown in Figure 1, will expand the Hg contaminated air stream across a supersonic nozzle into a high vacuum chamber. Light at 253.4 nm will be directed across the jet. Atomic Hg fluorescence will be Doppler shifted by between 1 and 3 GHz due to the jet motion ( Barat, 1996). Total collected light, comprised of the shifted fluorescence and stray elastic scattering, will be passed out of the vacuum chamber and through a sharp cutoff atomic mercury vapor filter to attenuate stray elastic scattering while transmitting the fluorescence signal.

As illustrated in Figure 2, when narrow bandwidth radiation is incident upon a high speed flow field, elastically scattered background light is superimposed upon the Doppler shifted mercury vapor fluorescence. If the excitation source coincides exactly with the absorption band of an optically thick mercury vapor, and, if a cell filled with mercury vapor is placed in front of a detector, then the elastically scattered background light will be strongly attenuated ( Miles, 1991; Finkelstein, et al., 1994).

The expansion reduces the collision rate of excited mercury with the air, so collisional quenching and collisional broadening are both substantially reduced. The low temperature associated with this expansion further reduces the fluorescence linewidth, enhancing the performance of the mercury vapor filter.

APPROACH  COMPOUNDED HG In general, mercury compounds absorb light strongly below 250 nm [ Gowenlock and Trotman, 1955], and these absorption bands are dissociative. In PFF, a photolyzing UV photon dissociates the target molecule into fragments, some of which are imparted with excess energy. The energy might then be lost by fluorescence:

h n A B > A + B * ( 1a) B* > B + h n ' ( 1b)

where A and B can be atoms or polyatomic species. The fragment identities and distributions, as revealed in the fluorescence spectrum, can, in principle, provide information on the composition of the target, in a manner analogous to mass spectrometry and other fragmentation spectroscopies. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 42 For example, Figure 3 shows the PFF spectrum from 193 nm excimer laser excitation of Hg( CH3) Cl vapor in a static cell ( Poulos and Barat, 1997). Two features are evident: atomic Hg emission lines at 546, 577, and 579 nm; and a broad continuum assigned to the B> X system of HgCl** excited state. Some of the following photochemical processes could explain these findings:

h n Hg( CH3) Cl > HgCl** + CH3 ( 2) HgCl** > HgCl + h n ' ( 2a) > Hg + Cl ( 2b)

Processes ( 2a) and ( 2b) are clearly implicated, but the origin of the Hg atomic emission lines is open to question.

The concentration of the target compound may be related to the fluorescence intensity from a hot fragment. For example, excitation laser energy of 2 mj/ pulse at a repetition rate of 10 Hz at 229 nm was applied to HgCl: vapor in a static cell ( Poulos and Barat, 1997). Analyte concentrations were varied by changing the bath temperature around an analyte reservoir of the static optical cell used. The PFF signal was monitored at 253.7 nm, the strongest fluorescence line. As shown in Figure 4, signal linearity was observed over at least 2.5 orders of magnitude of concentration. The concentrations studied overlap the range of inorganic mercury levels measured exiting from stacks of coal powered utilities and municipal waste incinerators by standard methods.

The supersonic jet spectroscopy are expected to further improve sensitivity of PFF detection. Fluorescence spectra will be sharpened, leading to better discrimination of fragment vibrational structure. Quenching by O2 will be reduced due to the low pressure. The UV source will penetrate deeper into the sample because there is no optical filtering of the light by O2 from the window to the jet, and reduced filtering in the jet.

QUALITY ASSURANCE/ PERFORMANCE ASSESSMENT For comparison of time averaged test concentrations, the mercury containing sample stream will be diverted to a reference method, such as optical absorption. Testing of the research technology will consist of obtaining data on five performance measures:

Relative Accuracy: the absolute mean difference between the metals concentration determined by the monitor and that determined by the reference method, plus a 2.5 percent uncertainty confidence coefficient based on a test series.

Calibration Drift: the difference in the monitor output reading from the established reference value after a stated period of operation. The reference value is established by a calibration standard which has a concentration nominally 80 percent or greater of the full scale reading capability of the monitor.

Zero Drift: calibration drift when the reference value is zero.

Response Time: the time interval between the start of a step change in the concentration of the monitored gas stream and the time when the output signal reaches 95 percent of the final value.

Detection Limit: three times the standard deviation of nine repeated measurements of a low level ( near blank) sample.

IN CONCLUSION This program will determine the capabilities and limitations of mercury detection in real time by the proposed techniques. It is anticipated that the detection limits for elemental mercury will be on the order of 0.1 µ g/ m3 ( ca. 10 pptv). It is desirable that response be linear up to cat 5000 µ g/ m3. It is anticipated that PFF signals will successfully discriminate between species such as HgCl2, HgO, Hg( CH3) 2, and Hg( CH3) Cl, at detection levels below 1 µ g/ m3.

ACKNOWLEDGMENT The author would like to thank Dr. Arthur T. Poulos, President of Poulos Technical Services, Inc., for his significant WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 43 contributions to this research. The author would also like to thank the U. S. Environmental Protection Agency  National Center for Environmental Research and Quality Assurance for its financial support of this work, and grant project officer Mr. William Stelz for his administrative guidance.

REFERENCES Baeyens, W., Trends in Analytical Chemistry, vol. 11, 245 ( 1992). Barat, R. B., " Real Time Trace Detection of Elemental Mercury and its Compounds," research proposal to U. S. Environmental Protection Administration, NCERQA, Analytical and Monitoring Methods ( 1996). Finkelstein, N., Gambogi, J., Lempert, W. R., Miles, R. B., Rine, G. A., Finch, A. and Schwarz, R. A., Proceedings of 32nd Aerospace Sciences Meeting, January, 1994, Reno, NV, Paper # A1AA 94 0492. Gowenlock, B. G. and Trotman, J., J. Chem. Society, pt. 2, 1454 ( 1955). Miles, R. B., " Absorption Line Filter Window and Method for Velocity Measurements by Light Scattering," U. S. Patent # 4,988,190 ( 1991). Poulos, A. T. and Barat, R. B., '' Detection of Mercury Compounds in the Gas Phase by Laser Photo Fragment Fluorescence," submitted to Applied Spectroscopy ( 1997). Von Burg, R. and Greenwood, M. R., in Metals and Their Compounds in the Environment, ed. by E. Merian, VCH, Weinheim ( 1991).

Figure 2. Mercury Atomic Filter Concept WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 44 Figure 1. Experimental Test Apparatus Figure 3. PFF Spectrum of Hg( CH3) Cl Figure 4. PFF Intensity ( at 254 nm) vs. HgCl2 Concentration WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 45 ELECTRODIALYTIC NAOH ELUENT PRODUCTION AND GRADIENT GENERATION Purnendu K. Dasgupta Texas Tech University, Lubbock, TX 79409 1061 A small inexpensive system is described that allows high performance suppressed anion chromatography on a capillary scale. A fully computer controlled stepper motor driven syringe type dispenser, equipped with a 500 mL capacity glass syringe is capable of pumping at pressures up to 1000 psi when equipped with an appropriate inlet check valve. Fused silica capillary columns ~ 50 cm in length and 180 mm in i. d., packed in house with a commercial packing, provide excellent performance, significantly exceeding the efficiencies observed for the same packing in commercially avaiIable 2 mm bore format. The system operates with a pressure drop of < 800 psi at a flow rate of 2 mL/ min. The system utilizes a novel electrodialytic NaOH eluent generator that is deployed on the high pressure side of the pump and thus requires no special measures for electrolytic gas removal This device permits both isocratic and gradient operation with excellent eluent purity; the NaOH concentration is generated linearly with applied current with near Faradaic efficiency up to a concentration of at least 100 mM.

                                                                                SENSORS FOR DIRECT MONITORING OF ENVIRONMENTAL POLLUTANTS F. Yan, M. Masila, A. Sargent, and Omowunmi A. Sadik Department of Chemistry, State University of New York at Binghamton, PO Box 6016, Binghampton, NY 13902 6016 Ph ( 607) 777 4132 Fax: ( 607) 777 4478 The considerable amount of time and costs involved in carrying, out field sampling and laboratory analysis of environmental samples has resulted in the need to develop alternative screening methods. Immunosensors are capable of " decentralizing" environmental testing through on site rapid screening. Current research and development efforts are directcd towards more compact cheap, and user friendly devices. In our laboratories we are pursuing the development of portable, rapid, cost effective, and in situ, multi layer electro optical sensors for continuous detection of environmental samples in real time. In our previous work, we have shown that conducting electroactive polymer ( CEP) based sensors possess significant advantages over conventional methods of detection and quantitation of environmental analyses. Also the uniqueness of CEP based sensors in combining the role of transducers required for measuring immunological reactions with that of antibody ( Ab) entrapment matrices translates into substantial equipment miniturization as well as huge reduction in response time. This promises to open up new horizons in environmnental monitoring, medical and clinical applications. This paper will discuss the deveIopment of a direct multi electrode array detection and quantitation of polychlorinated biphenyls ( PCBs), heavy metals, and atrazines, using CEP based sensors. Preliminary results obtained with enzyme based electro optical detection methods will aIso be analyzed and discussed. The advantages of utilizing these types of assay formats to provide unparalleled rapid, sensitive, and cost effective options for environmental analsis of pesticides will be presented. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 46 INORGANIC WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 47 WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 48 PRACTICAL CLEAN CHEMISTRY TECHNIQUES FOR TRACE AND ULTRA TRACE ELEMENTAL ANALYSIS H. M. " Skip" Kingston and Peter J. Walter Duquesne University, Department of Chemistry & Biochemistry, Pittsburgh, PA 15282 1503 Trace and ultra trace analysis is as much dependent on the control of the analytical blank as it is on the accuracy and precision of the instrument making the measurement. Inability to control contamination that is external to the sample, or those contributions of the analyte coming from all other sources than the sample, is frequently the limiting factor in trace ( parts per million ( ppm) to parts per billion ( ppb)) and ultra trace analysis ( ppb to parts per trillion ( ppt)). Analytical blank contributions occur from four major sources: surroundings, reagents, vessels, and the analyst's technique.

The analytical blank can be dramatically reduced through the combination of clean chemistry and microwave sample preparation. Microwave sample preparation systems minimizes continuous sustained transfer of elements from the air to the sample solution by providing a controlled, closed, or restricted sample container during decomposition1 It prevents the entry of the laboratory atmosphere and thus prevents the majority of environmental airborne contamination. This leaves only the air within the vessel, captured during transfer, and digestion/ extraction. To prevent this volume of air from contaminating the sample, the sample must be transferred in a clean environment.

Portable class 100 clean benches were designed and produced to allow for addition of sample and reagents, and to open or close vessels of both the atmospheric and closed vessel design. These carts can be constructed for $ 1,000$ 1,600, depending on whether they need to be exhausted or are just islands of clean laboratory air. Similar portable clean systems are becoming available from analytical instrument manufacturers. A clean laboratory of dimensions 18' x 13.5' was designed and constructed for approximately $ 30,000 using readily available materials and specialized HEPA clean hood components. This clean facility is used for both microwave vessel sample preparation and ICP MS analysis. The ICP MS is located in the clean laboratory, so its extremely low detection capability may be utilized.

95% of the capability of a cleanroom can be made available to standard environmental laboratories for between $ 1,500 and $ 15,000. The quality of the analysis can be improved for ultra trace analysis of many type for modest cost. Some of these relatively low cost systems will be described for both their effectiveness and method of implementation. These modest cost methods will be proposed for inclusion in chapter 3 of SW 846 as guidelines to improve environmental analytical analysis.

1. H. M. Kingston, P. J. Walter, S. J. Chalk, E. Lorentzen, and D. Link, Chapter 3: Environmental Microwave Sample Preparation Fundamentals, Methods, and Applications In Microwave Enhanced Chemistry; H. M. Kingston, S. Haswell, Eds.; American Chemical Society: Washington, D. C. ( 1997).

                                                                                FLAME ATOMIC ABSORPTION FOR THE DETERMINATION OF ARSENIC AND SELENIUM IN TCLP EXTRACTS Zoe Grosser The Perkin Elmer Corporation, 50 Danbury Road MS 219 Wilton, CT 06897 0219 grosseza@ perkin elmer. com ABSTRACT Toxicity Characteristic testing is performed to assess the potential of a material to leach hazardous constituents after disposal in a landfill. The Toxicity Characteristic Leaching Procedure ( TCLP) extract solution is analyzed for 31 organic components and 8 metals and if the regulated limits are exceeded the material is considered hazardous and must be treated appropriately. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 49 Currently approved EPA Methods for the determination of As and Se include graphite furnace atomic absorption ( GFAA) ( 7060A, 7740) and hydride generation atomic absorption ( 7061A, 7741A). With the advent of modern instrumentation, including electrodeless discharge lamp light sources, more stable electronics, background correction, and improved sample introduction systems, flame atomic absorption analysis for low levels of these elements becomes viable.

Detection limits ten times below the MCL are generally accepted as necessary to ensure reliability at the decision making point. Method detection limits were calculated for As and Se based on the EPA procedure published at 40CFR, part 136. The method detection limit obtained for As was 0.12 ppm and for Se was 0.04, using the high sensitivity nebulizer. The detection limit for As would also be lower using the high sensitivity nebulizer ( 0.04), but meets our goal of ten times below the MCL ( 0.5 ppm needed) with the universal nebulizer.

Calibration is an important component of an analysis and we will discuss the choice of calibration standards and the resulting calibration. The linear range will be documented and the value of extending the calibration curve past the linear range will be discussed.

The developed flame atomic absorption method will be applied to the analysis of As and Se in real TCLP samples.

INTRODUCTION One of the more popular tests performed under the EPA Resource Conservation and Recovery Act ( RCRA) program is the Toxicity Characteristic Leaching Procedure ( TCLP). TCLP testing is performed to assess the potential of a material to leach hazardous constituents after disposal in a landfill. The first step involves extraction of the potentially hazardous material ( method 1311) with a mildly acidic buffered solution. The extract is then analyzed for 31 organic compounds and 8 metals and if any of the analyses are present at levels exceeding the maximum allowed, the material is considered hazardous and must be treated as such. Table I lists the maximum contaminant levels ( MCLs) permitted in the extract for metals.

Table I. TCLP Metal Limits 5.0 Ag 1.0 Se 0.2 Hg 5.0 Pb 5.0 Cr ( total) 1.0 Cd 100 Ba 5 As MCL ( mg/ L) Element The methods for contaminant analysis can come from many reputable sources but the EPA RCRA publication Test Methods for Evaluating Solid Waste, Physical/ Chemical Methods; SW 846 is a primary source for many organizations performing RCRA measurements. The methods available in SW 846 for As and Se determination are listed in Table II.

Table II. RCRA SW 846 Methods  6010 7741A 7740 Se 6020 6010 7061A 7060A As ICP MS ICP OES Hydride GFAA With the advent of modern instrumentation including electrodeless discharge lamp light sources more stable electronics background correction and improved sample introduction systems flame atomic absorption determination of these elements becomes viable. Flame atomic absorption is an inexpensive technique to acquire and operate and WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 50 many laboratories might prefer the choice if a method was readily available.

The goal of this paper is to evaluate the possibility of FLAA for the determination of As and Se in TCLP extracts. The detection limits will be determined to assess the analytical feasibility. The linear ranges and potential interferences will be evaluated. Stability over the course of an unattended analytical run and the recovery of spikes in real matrices will be presented.

EXPERIMENTAL The Perkin Elmer ® AAnalyst   100 atomic absorption spectrometer was used for all measurements. The analytical parameters are shown in Table III. The high sensitivity GemTip   nebulizer was used exclusively for Se because the estimated detection limits indicated that the additional sensitivity would be required. The universal and high sensitivity GemTip   nebulizers were both evaluated for As. Standards were prepared to contain approximately 1% HNO3 and 2% HCI ( GFS Chemicals ® , Columbus, OH)

Table III. AAnalyst 100 Instrumental Conditions 0.1, 0.5, 1.0, 2.0 0.2, 2.0, 5.0, 10.0 Standards ( mg/ L) Linear Linear Calibration High Sensitivity Universal or High Sensitivity Nebulizer Air Acet. Air Acet. Flame AA BG AA BG Mode 2.0 0.7 Slit ( nm) 196.0 193.7 Wavelength ( nm) Se As Parameter Keith Hutchinson of NET Midwest, Inc. provided the digested TCLP extracts. The synthetic sample was prepared to approximate the provided samples by combining single element stock solutions to create a matrix of 1500 mg/ L Na, 20 mg/ L Ca, and 70 mg/ L Fe.

RESULTS AND DISCUSSION Detection limits ten times below the MCL are generally accepted as necessary to ensure reliability at the decision making point. This means that we would need a detection limit for As of 0.5 mg/ L and 0.1 mg/ L for Se to meet the goal. Method detection limits were calculated based on the EPA procedure published at 40CFR, part 136 1. The detection limits shown in Table IV meet the goals described. The universal nebulizer is adequate for the measurement of As or the high sensitivity can be used for additional margin. The high sensitivity nebulizer is necessary to meet the goals for the determination of Se.

Table IV. Method Detection Limits ( MDLs)

0.041 0.043 High Sensitivity  0.12 Universal Se As Nebulizer Linear ranges must be determined initially to characterize instrumental performance. It is generally accepted that a calibration is no longer linear when the measured concentration based on a lower level calibration deviated from the the value by more than 5%. Using a spreadsheet program to calculate the percentage difference at increasing concentrations the linear range was rounded off to 20 mg/ L for Se and 60 mglL for As. Figure 1 shows the curves for Se and Figure 2 shows the analogous curves for As ( universal nebulizer).

Modern instruments using algorithms to reliably model the curves obtained at higher concentration can give accurate and precise measurements above the linear range. The choice of calibration standards is more critical and three standards should be used in a ratio of 6: 3: 1, with 6 representing the highest concentration2. If performance can be WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 51 verified through the use of quality control checks for calibration verification precision and recovery this extends the useful working range of the instrument. For atomic absorption with one of the shorter working ranges this can improve the range four six times above the concentration at the top of the linear range.

Figure 1. Se linear range.

Before measuring real samples a synthetic sample was evaluated to determine if matrix effects were present. As and Se were spiked at a low level and at the MCL into a synthetic matrix approximated from ICP MS analysis of a digested sample. Table V shows the results indicating that the matrix was not a problem for the sample introduction system.

Figure 2. Arsenic linear range.

Table V. Synthetic Sample Results 95.2 1.0 93.0 0.5 Se 92.2 5.0 113 0.5 As % Recovery High Spike ( mg/ L) % Recovery Low Spike ( mg/ L) Element The analysis of samples spiked before the digestion process can indicate the entire process is in control. This includes the digestion instrument calibration, and method. Laboratory control samples provided from NET spiked at 1 mg/ L prior to digestion are shown in Table VI.

Table VI. Predigestion Spikes % Recovery of 1 mg/ L Spike 108 109 4 23B 102 99.3 4 19E Se As Sample The percentage recovery falls between 99.3 to 108% well within the EPA limits of 80 120% recovery of the expected value.

Post digestion spikes were added to TCLP samples at a low level and high level to confirm the method performance with a variety of matrices. The results are shown in Table VII and demonstrate acceptable recoveries in all cases. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 52 Table VII. Post Digestion Spike Results 93.2 1.0 98.1 5.0 333133 105 1.0 89.8 5.0 333132 98.6 0.5 95.5 1.0 333131 102 0.5 106 1.0 333130 99.0 0.5 107 1.0 3 16M LCS % Recovery Spike Added ( mg/ L) % Recovery Spike Added ( mg/ L) Selenium Arsenic Sample Productivity is an important component of an environmental analysis and TCLP digests contain a fairly high amount of dissolved material. The stability of a standard was monitored during an autosampler analysis of 160 samples at regular intervals. The 5 mg/ L As standard was recovered within ± 5% of the expected value during the more than 2 hour run. The 1 mg/ L Se standard was recovered within ± 6% of the expected value.

CONCLUSIONS Modern flame atomic absorption can meet the analytical requirements of a TCLP digest analysis. The method detection limits are more than ten times below the MCL where a decision is made. The linear range has been characterized and provides a useful range for the amounts of As and Se expected in a typical digested sample. The useful concentration could be extended with the use of nonlinear calibration curves. Recoveries in synthetic and real samples demonstrate freedom from interferences and the utility of the method.

Flame atomic absorption is less time consuming and labor intensive than GFAA or hydride analysis. If used in the determination of the full suite of TCLP metals, it can help reduce the number of techniques required for the analysis of 8 metals. Consolidation of techniques can reduce the analysis time for a sample and improve turnaround time.

The EPA should be encouraged to include a flame atomic absorption method in SW 846 that includes these elements. Data demonstrating performance at low levels will give laboratories additional flexibility in choosing the method best suited for the analytical scenario and business requirements.

ACKNOWLEDGMENTS Thanks to Keith Hutchinson and Jackie Webster of NET Midwest, Inc. for the digested TCLP extracts. Thanks to Dr. Ruth Wolf, Perkin Elmer, for the ICP MS TCLP profile.

REFERENCES 1. United States Code of Federal Regulations 40 Part 136 Appendix B ( July 1, 1996). 2. Barnett W. B. Spectrochim. Acta. 39B ( 6) 829 ( 1984).

                                                                                FIELD AND LABORATORY ANALYSIS OF MERCURY Peter J. Walter, H. M. " Skip" Kingston, Helen Boylan, and Ye Han Duquesne University, Department of Chemistry & Biochemistry, Pittsburgh, PA 15282 1503 Mercury is a toxic element in many chemical forms whose analysis is hampered by its intrinsic mobility and volatility. There is a potential for loss of mercury during every stage of analysis including: collection, storage, sample preparation, and analysis. Collection and storage of the sample can have adverse effects on the mercury concentration and its species. Sample preparation can lose mercury during drying, digestion, and reactions of the mercury with vessel walls. Analyses of mercury are also hampered by mercury reacting or sticking to components of WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 53 the analysis system. Two approaches to solving these problems are evaluated: analysis of mercury through direct analysis of solid materials, requiring little or no sample preparation; and alternatively identification of sources of mercury loss during every stage of sample preparation1.

Using an automated mercury analyzer ( AMA 254, Milestone S. r. l), the solid or liquid sample can be directly analyzed without sample preparation. This technique is capable of on line decomposition of solid samples in an oxygen furnace while collecting the mercury as an amalgam2. Alternatively, a liquid sample can be introduced into the oxygen furnace with the mercury collected as the amalgam. Subsequent release of the mercury into a detector leads to total mercury analysis at the nano gram level. Due to the instruments rugid and compact design this instrument will be demonstrated as a field technique as well as being compatible for direct and decomposed samples. This is one of the first field capable instruments that has the potential to produce laboratory quality data in field environments.

Traditional sample preparation steps are evaluated for mercury quantitation. Drying of the sample in an oven, vacuum drying, and other techniques rely on different mechanisms for drying which show varying degrees of mercury loss. Typically, acid digestion of a sample in a closed vessel retains the mercury. Standard EPA SW 846 Methods 3052, 3051A, 3015A, and 3050B will be evaluated for their recovery of mercury3. Many analysis techniques require matrix conversion after digestion. This conversion may inadvertently unstabilize the mercury ions, leading to elemental loss This study will demonstrate that a mercury analyzer is capable of analyzing solid and liquid samples, either the collected sample or the acid digest solution, at trace levels in the laboratory or in the field. For these reasons, we have proposed EPA standard method 7473 for the analysis of solid and liquid samples either in the laboratory or the field.

1. Walter, P. J., Kingston, H. M. " The Fate of Mercury in Sample Preparation", Pittsburgh Conference, Atlanta, GA, 1997, paper no. 1223. 2. Salvato, N., Pirola, C., " Analysis of mercury traces by means of solid sample atomic absorption spectrometry", Mikrochimica Acta 123, pp. 63 71, 1996. 3. H. M. Kingston, P. J. Walter, S. J. Chalk, E. Lorentzen, and D. Link, Chapter 3: Environmental Microwave Sample Preparation Fundamentals, Methods, and Applications In Microwave Enhanced Chemistry; H. M. Kingston, S. Haswell, Eds.; American Chemical Society: Washington, D. C. ( 1997).

                                                                                LEGALLY DEFENSIBLE SPECIATED MEASUREMENTS USING SIDMS H. M. " Skip" Kingston, Dengwei Huo, Yusheng Lu, and Peter J. Walter Duquesne University, Department of Chemistry and Biochemistry, Pittsburgh, PA 15282 1503 A new method for the accurate determination of chemical species in the environment has been developed: Speciated Isotope Dilution Mass Spectrometry ( SIDMS) 1. This method utilizes isotopically enriched speciated spikes combined with isotope dilution to accurately determine and correct for specie transformations that occur in sample processing. The errors in the measurement are those that are limited by the ability of the ratio measurement and the equilibrium of the species. It was specifically developed to address the problems of accurately quantifying different species in complicated matrices. Additionally, it is a diagnostic tool for identifying both the error and bias inherent in specific methods of sampling process, storage, sample preparation, and measurement. SIDMS is applicable to most non monoisotopic elements and extends to various oxidation states, organometallics, and molecular forms of species.

Data for species such as the highly reactive Cr( VI) and Cr( III) demonstrate the capabilities of this method. Currently these species are extracted from soil using Method 3060A and are analyzed with Method 7196A. Both extraction and analysis methods are biased in the speciation measurement process. SIDMS is capable of accurately correcting back to the original concentration samples in which > 50% degradation of Cr( VI) to Cr( III) during sample processing. These unique capabilities will eventually make it possible to establish standard speciation measurement methods and to develop standard sampling procedures for speciation. The method permits bias correction for degradation of the analyte species during collection, storage, extraction and chemical manipulation. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 54 A new reference method based on Speciated Isotope Dilution Mass Spectrometry will be proposed to permit the implementation of this procedure. The objective is to provide a legally defensible reference method for measurements that have high degrees of uncertainty and error due to highly reactive analyses such as species.

1. Kingston, H. M., Patent Number 5,414,259, " Method of Speciated Isotope Dilution Mass Spectrometry", U. S. Patent, Filed U. S. Patent Office, Granted May 9, 1995. 2. Kingston, H. M.; Huo, D.; Chalk, S.; Walter, P. J., " The Accurate Determination of Species by Speciated Isotope Dilution Mass Spectrometry: Exemplified by the Evaluation of Chromium ( VI) in Soil", Proceedings from the 12th Annual Waste Testing & Quality Assurance Symposium, July 23 26, 1996, pp 112 119.

                                                                                EPA METHODS 3015A AND 3051A: VALIDATION STUDIES FOR UPDATED MICROWAVE LEACH METHODS Dirk D. Link, Peter J. Walter, and H. M. " Skip" Kingston Duquesne University, Department of Chemistry and Biochemistry, Pittsburgh, Pennsylvania 15282 1503 ABSTRACT Validation studies for two recently proposed updated microwave leach methods ( Method 3051A and Method 3015A) have been conducted. These updated methods allow for the inclusion of hydrochloric acid in the leaching mixture for complexation and stabilization of certain RCRA regulated elements. Experimental details of the validation procedure are discussed. Experimental data demonstrates the effectiveness of inclusion of HCl in recovering analyses like antimony, silver and iron. Final validation data for Method 3051A is presented. Validation for Method 3015A has also progressed, with enhancements in " problem" analyte recoveries also being shown.

INTRODUCTION Recently, updated versions of two microwave extraction methods have been proposed for acceptance by the EPA to be included in the next update of SW 846. These updated methods are EPA Method 3051A, an acid leach method for sediments, sludges, soils, and oils; and EPA Method 3015A, an acid leach method for aqueous samples. EPA microwave leach Method 3051 was proposed as an alternative to EPA hot plate leach Method 3050 ( B). However, because Method 3051 is limited to the use of nitric acid only, it does not recover certain " problem" analyses as completely as Method 3050, which also includes hydrochloric acid and hydrogen peroxide. Some examples of these " problem" analyses are antimony, silver, and high concentrations of iron. These metals, and others, are not stable in the strong oxidizing environment of nitric acid only digestions. The updated microwave methods provide the analyst with options for using alternate reagent combinations to enhance the performance and appropriateness of the methods for certain analyses. For example, preliminary results have demonstrated that the recovery of antimony increases from 0% in an all nitric digest to almost 80% in a digest using both nitric acid and hydrochloric acid1. The chemistry of the updated methods has been modified to accurately reproduce the chemistry of the standard EPA hot plate methods. The option to combine hydrochloric acid with the nitric acid in the optimized ratio of 9 mL HNO3 to 3 mL HCl, is provided to enable the complexation and stabilization of elements such as aluminum, antimony, iron, and silver, when needed. This acid ratio has demonstrated optimum recoveries for all 26 RCRA regulated elements. It increases recoveries of certain analyses without sacrificing the recoveries of other RCRA regulated metals. Data demonstrating the need for inclusion of HCl in the microwave methods will be presented. The enhanced performance of this updated microwave leach method will be demonstrated for a variety of matrices, namely a sediment sample ( SRM 2704, Buffalo River sediment), a sludge sample ( a 1 to 1 mixture of SRM 2704 and SRM 1634c, Trace Elements in Fuel Oil), a soil sample ( SRM 4355, Peruvian soil), and an oil sample ( SRM 1084a, Wear Metals in Oil). Final validation for Method 3051A will be demonstrated by comparing the recovery data from these matrices using the all nitric Method 3051 digest with the data using the nitric and hydrochloric mixed acid Method 3051A digest.

EPA Method 3015 is also a nitric acid only leach, and does not allow for inclusion of HCl for complexation and WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 55 stabilization of certain analyses. In proposed EPA Method 3015A, the inclusion of HCl along with HNO3 in the leaching acid mixture should overcome the complexation difficulties demonstrated in nitric only leaches. Digestions using both the nitric only Method 3015 and those using the nitric and hydrochloric mixed acid Method 3015A are compared. The results of including HCl in the leaching mixture for aqueous samples parallel those for solid samples. Recoveries of problem analyses increase while recoveries of other analyses are preserved. In addition, validation for the elements boron, mercury, and strontium was not provided for Method 3015. By analyzing for these elements in the current validation study of EPA Method 3015A, possible validation for these three RCRA regulated elements will also be examined.

EXPERIMENTAL The validation study for Method 3051A consisted of an initial re optimization of the acid ratio to be used in the method. This was accomplished by comparing the results of four leaches of SRM 2704 ( Buffalo River sediment) using different acid combinations. Initially, 10 mL HNO3 only was used ( 10: 0). Subsequent acid mixtures consisted of 9 mL HNO3 + 1 mL HCl ( 9: 1), 9 mL HNO3 + 3 mL HCl ( 9: 3), and 9 mL HNO3 + 5 mL HCl ( 9: 5). The goal of these acid ratio studies was to determine the optimum amount of HCl for maximum complexation while still achieving similar oxidizing strength of the acid mixture. Excessive dilution of the HNO3 with the HCl would lead to incomplete recoveries of analyses, thus introducing another bias. Also, as the method must be valid for all 26 RCRA regulated elements, it is not appropriate to optimize the method for only a few of the analyses ( i. e. antimony or iron). The final method must be optimized for recovering all RCRA regulated analyses. Elemental analysis was performed either by Inductively Coupled Plasma Mass Spectrometry ( ICP MS) or by Flame Atomic Absorption Spectrometry ( FAAS).

Upon re optimizing the acid ratio, the remainder of the validation study consisted of comparing the recoveries using the nitric only Method 3051 versus using the nitric and hydrochloric mixed acid 3051A. Comparisons were made using the three remaining types of matrices for which 3051 is applicable, namely sludge, soil, and oil. Recoveries using the 10: 0 versus using the 9: 3 digests were compared, as well as recoveries from the hot plate Method 3050. Data for the hot plate method was taken from the original report for the validation of Method 3050 and 3051 2. The results demonstrated by the 9: 3 3051A leach method suggest that it is a valid alternative leach method, achieving comparable results to those of the hot plate leach Method 3050.

The validation experiments for the aqueous leach Method 3015A paralleled those for the solid sample leach method 3051A. The samples used were simulated wastewater samples prepared just prior to the leach digestion. Simulated wastewaters were used because of the lack of appropriate standard reference materials for wastewater type matrices. Additionally, the validation study for the original aqueous leach method 3015 was performed using a simulated wastewater. The wastewaters were prepared from the same SRM's used in the 3051A validation study, combining approximately 0.35 grams of the solid samples with 45 mL double deionized water in each digestion vessel just prior to acid addition. The SRM's used were SRM 2704 ( Buffalo River sediment), SRM 4355 ( Peruvian soil), SRM 1084a ( Wear Metals in Oil), and a 1 to 1 mixture of SRM's 2704 and 1634c ( Trace Metals in Fuel Oil).

Digestions were performed for the wastewater samples using either 5 mL HNO3 only ( Method 3015) or 4 mL HNO3 and 1 mL HCl ( 3015A). Elemental analysis was performed using either ICP MS or FAAS. The recoveries of analyses using each acid mixture were compared. Once again, the addition of hydrochloric acid provided better complexation and stabilization of problem analyses while preserving the recoveries of other analyses. Also, the proposed Method 3015A has demonstrated that it is effective for the elements boron, mercury, and strontium. Validation for these three RCRA regulated elements was not provided in the original validation of Method 3015.

RESULTS AND DISCUSSION The following figures illustrate the data for the re optimization of the 3051A acid ratio. As discussed, analyses were leached from SRM 2704 using these four acid ratios: 10: 0, 9: 1, 9: 3, and 9: 5. For the " problem" analyses shown, the acid ratio of 9: 3 provides optimum complexation. The most dramatic case is for antimony, whose recovery increases from approximately 0% in the nitric only digest to greater than 80% in the 9: 3 digest. Other recovery increases are shown for iron and vanadium. The remaining figures demonstrate that the 9: 3 mixture also retains the overall oxidizing strength of the acid mixture, hence preserving the recoveries of the other analyses. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 56 Figure 1. Recovery of antimony vs. acid ratio Figure 2. Recovery of iron vs. acid ratio used used in leach digest. in leach digest.

Figure 3. Recovery of vanadium vs. acid ratio used in leach digest.

The above figures illustrate the increased recoveries of Sb, Fe, and V as HCl is added to the leaching mixture. Also demonstrated is the optimization of the acid ratio at 9 mL HNO3 to 3 mL HCl. The analyte recoveries using the 9: 5 acid ratio either decrease slightly, or provide no further recovery enhancement. This indicates that the 9: 5 ratio is not as appropriate and that the 9: 3 ratio offers the highest level of complexation without compromising the overall oxidizing strength of the acid mixture. The figures below also illustrate that the oxidizing strength is not lowered, as the recovery of non biased analyses remains virtually the same when the 9: 3 ratio is used.

Figure 4. Recovery of cobalt vs. acid ratio used Figure 5. Recovery of beryllium vs. acid ratio in leach digest. used in leach digest.

With the acid ratio, re optimized at 9: 3 using leach data from SRM 2704, the remainder of the validation study continued. Three remaining matrices, a soil ( SRM 4355), an oil ( SRM 1084a), and a simulated sludge ( 1 to 1 mixture of SRM 2704 and SRM 1643c), were digested using both the nitric only Method 3051 and the nitric and hydrochloric mixed acid Method 3051A. The data demonstrates the increased recoveries of biased analytes with preservation of WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 57 other analyte recoveries. The recoveries for Method 3051A are comparable to those of Method 3050, the hot plate digestion that uses nitric acid, hydrochloric acid, and hydrogen peroxide. The following tables will demonstrate these improved recoveries using the microwave leach and their comparability to the recoveries using the hot plate leach. Analyte recoveries are expressed in µ g/ g unless otherwise indicated.

Table 1. Comparison of analyte recoveries from SRM 4355 ( Peruvian Soil) for alternative EPA leach methods ( µ g/ g ± 95% confidence interval, unless otherwise noted)

129 ± 26 131 ± 14.2 130.6 ± 5.1 126.7 ± 9.3 Pb 28.9 ± 2.8 17.1 ± 2.37 18.7 ± 0.68 14.6 ± 0.68 Cr ( 1.50)** 1.03 ± 0.202 1.09 ± 0.27 1.11 ± 0.31 Cd 4.45 ± 0.19% 2.98 ± 0.342% 3.28 ± 0.18% 2.8 ± 0.09% Fe ( 151)** 81.4 ± 17.3 123 ± 7.78 65.5 ± 2.12 V 14.8 ± 0.76 * 10.4 ± 0.826 0.202 ± 0.347 Sb Total 3050 3051A 3051 Element * Antimony was not analyzed in the 3050 validation study. ** Values in parenthesis are not certified concentrations and are for reference only.

The first three elements demonstrate the enhanced recoveries upon adding 3 mL HCl to the acid mixture. Especially dramatic is the enhancement for antimony, showing only 1% recovery for the nitric only digest but rising to approximately 70% upon adding 3 mL HCl. The remaining entries in the table demonstrate that recoveries of other analyses are preserved when the mixed acid is used.

Table 2. Comparison of analyte recoveries from SRM 1084a ( Wear Metals in Oil) for alternative EPA leach methods ( µ g/ g ± 95% confidence interval)

101.1 ± 1.3 100.8 ± 7.8 99.8 ± 6.5 Pb 101.4 ± 1.5 96.4 ± 7.0 92.5 ± 3.1 Ag 100.3 ± 1.4 93.2 ± 3.4 90.3 ± 2.4 Mo 100.0 ± 1.9 91.8 ± 3.6 92.2 ± 4.2 Cu 99.7 ± 1.6 92.9 ± 4.6 93.6 ± 2.0 Ni 99.5 ± 1.7 96.6 ± 4.9 92.9 ± 6.3 Mg ( 104)* 101.1 ± 6.6 98.0 ± 4.8 Al 98.3 ± 0.8 93.5 ± 3.1 91.2 ± 4.8 Cr Total 3051A 3051 Element * Values in parenthesis are not certified concentrations and are for reference only.

The recoveries of all analyses for the oil matrix are similar for both acid combinations. However, most recoveries for the mixed acid digest are slightly higher than the nitric only digest.

Table 3. Comparison of analyte recoveries from " simulated sludge" mixture of ~ 0.25 g SRM 2704 ( Buffalo River Sediment) and ~ 0.25 g SRM 1634c ( Trace Metals in Fuel Oil) for alternative EPA leach methods ( µ g/ g ± 95% confidence interval)

76.4 ± 8.17 78.2 ± 6.41 83.4 ± 7.05 Pb 1.67 ± 0.196 1.87 ± 0.431 1.81 ± 0.478 Cd < 4.0 0.216 ± 0.191 0.209 ± 0.067 Ag < 2.5 1.71 ± 0.61 1.53 ± 0.20 Mo 31.4 ± 5.56 29.3 ± 9.60 32.3 ± 6.06 Ni 5.89 ± 1.43 6.18 ± 1.18 7.69 ± 1.85 Co 42.3 ± 6.04 44.7 ± 2.99 49.7 ± 3.73 Cr 3050 3051A 3051 Element WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 58 Again, we see the, preservation of recoveries for the mixed acid, as well as good agreement with the hot plate 3050 recoveries. This simulated sludge matrix is highly heterogeneous, which may account for the greater variation seen in the data for this matrix.

The data presented serve as the final results of the validation study for EPA Method 3051A. It has demonstrated effectiveness for enhancing the recovery of " problem" analyses from four different matrix types while at the same time preserving the recovery of the remaining analyses. It has demonstrated comparable recoveries with hot plate Method 3050.

Validation for proposed Method 3015A proceeded using similar experimental procedures. Comparisons were made using an all nitric digest ( 5 mL HNO3) versus using a nitric and hydrochloric mixed acid digest ( 4 mL HNO3 + 1 mL HCl) on four " simulated wastewater" matrices. These matrices consisted of approximately 0.35 grams of solid sample mixed with 45 mL double deionized water ( per digestion vessel) immediately prior to acid addition and digestion. The solid samples used parallel those used for the 3051a study, namely SRM 2704, SRM 4355, SRM 1084a, and the mixture of SRM 2704 and SRM 1634c. The mixed acid digest should complex and stabilize certain problem analyses, leading to increased recoveries of these analyses. The leach recovery data for the 2704 wastewater and the 4355 wastewater are presented in the following tables.

Table 4. Comparison of analyte recoveries from " simulated wastewater" mixture of SRM 2704 ( Buffalo River Sediment) and double deionized water for EPA leach methods ( µ g/ g ± 95% confidence interval)

* 0.36 ± 0.115 0.33 ± 0.037 Ag 44.1 ± 3.0 39.9 ± 4.64 38.6 ± 4.24 Ni 438 ± 12 406 ± 8.7 392 ± 5.6 Zn 14.0 ± 0.6 11.9 ± 0.45 11.0 ± 0.47 Co * 0.95 ± 0.170 0.85 ± 0.116 Be * 2.92 ± 1.19 2.07 ± 1.71 Mo 95 ± 4 51.6 ± 2.23 32.6 ± 4.83 V Total 3015A 3015 Element * The total concentration of this analyte is not certified for SRM 2704.

The results for this " sediment wastewater" matrix demonstrate the enhanced recovery for certain analyses ( i. e. vanadium, molybdenum, and beryllium) and similar recoveries for other analyses using the nitric and hydrochloric mixed acid Method 3015A digest.

Table 5. Comparison of analyte recoveries from " simulated wastewater" mixture of SRM 4355 ( Peruvian Soil) and double deionized water for EPA leach methods ( µ g/ g ± 95% confidence interval)

129 ± 26 136 ± 4.7 135 ± 4.6 Pb ( 1.7)* 1.09 ± 0.13 0.98 ± 0.07 Mo ( 13)* 10.8 ± 2.40 11.1 ± 1.44 Ni 368 ± 8.2 418 ± 16.4 415 ± 16.2 Zn 14.8 ± 0.76 10.4 ± 0.51 10.5 ± 0.42 Co ( 1.9)* 1.62 ± 0.14 1.31 ± 0.16 Ag 14.3 ± 2.2 5.20 ± 0.67 3.70 ± 0.37 Sb ( 151)* 38.7 ± 5.94 33.9 ± 3.57 V Total 3015A 3015 Element * Values in parenthesis are not certified concentrations and are for reference only.

This set of digestions also demonstrates that inclusion of HCl enhances the recovery of certain analyses ( V, Sb, Ag) while preserving the recovery of other analyses. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 59 Two additional types of simulated wastewater matrices are currently in the digestion and data acquisition process for the validation of proposed Method 3015A. These are the oil wastewater ( SRM 1084a and DDI water) and the " sludge" wastewater ( SRM's 2704 and 1634c and DDI water). It is expected that similar enhancements in " problem" analyte recoveries, as well as preservation of other analyte recoveries will be demonstrated by the mixed acid digest.

SUMMARY The final validation data for proposed EPA Method 3051A has been given. The data shows the effectiveness of including HCl in the leaching acid mixture for enhancing the recoveries of " problem" RCRA regulated metals such as antimony and iron. This mixed acid also shows comparable recoveries for other non biased analyses. This updated microwave leach method minimizes the reagent induced biases between the two alternative leach methods 3050 ( hot plate) and 3051 ( microwave). This study also demonstrates the effectiveness of adding HCl in Method 3015A for the leaching of aqueous samples ( wastewaters). Data for digestions of two matrix types using the mixed acid leach Method 3015A has demonstrated similar enhancements in recoveries. Digestions for the remaining two wastewater matrix types are in progress, with similar enhancements in the recoveries of problem analyses expected.

A paper explaining the depth of the information in this validation study is in preparation. The discussion will include chemical equilibria and other data documenting the reactions and summarizing these results.

REFERENCES 1. Link, D. D.; Walter, P. J.; Kingston, H. M.; " EPA Methods 3015A and 3051A: Validation Studies for Updated Microwave Leach Methods", Paper 1121, Pittsburgh Conference, March, 1997, Atlanta, GA. 2. Binstock, D. A., Yeager, W. M., Grohse, P. M., Gaskill, A.; " Validation of a Method for Determining Elements in Solid Waste by Microwave Digestion", Technical Report Draft, November, 1989.

                                                                                LONG TERM STABILITY OF ICP SPECTRAL REGISTRATION BY MANAGEMENT OF THE MODELS: APPLICATION TO QUANTITATION USING MULTIVARIATE ANALYSIS Christopher P. Hanna, Ph. D., Senior Staff Scientist; Alan M. Ganz, Ph. D., Director; Clinical Instrumentation, Perkin Elmer Corporation, 50 Danbury Road, Wilton, CT 06897 0208 ABSTRACT A mathematical technique is described which provides constancy of multivariate analysis models in ICP emission spectroscopy. Once an analysis protocol has been developed, the profiles of all active spectral components are saved in an archive. Through the use of well defined spectral standards, this archive can be mathematically transformed at any time to correspond to any new conditions for an instrument. This results in analytical measurements which are completely independent of wavelength accuracy and wavelength calibration, providing not only exceptional long term accuracy, but also complete transferability of ICP emission methods between instruments. Preliminary analytical results are shown which illustrate the utility of this technique.

INTRODUCTION ICP emission spectroscopy is frequently applied for the determination of metals and metalloids in a wide variety of environmental matrices. Mathematical procedures are often required for the correction of background shifts and spectral overlaps, and are well represented in promulgated regulations ( particularly the use of interelement correction factors, or IECs). While the IEC technique works properly in well defined circumstances, it does not lend itself well to all situations1. Some examples are: 1) IECs require the careful selection of background correction points, which often requires a lengthy and somewhat subjective selection process; 2) slight differences in plasma conditions in the course of an analysis can render the IEC factors nonviable due to changing line intensity ratios; 3) IEC factors are not always linear across all concentration ranges of an interferent.

Multivariate calibration techniques have been used in ICP emission spectroscopy for interference correction, particularly when array based solid state detectors are used2 4. Multivariate calibration techniques provide WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 60 exceptional capacity for resolving spectral overlaps in a straightforward manner2, and provide improved analytical precision through the process of redundant sampling3. Numerous suggestions for improved multivariate methods have been made during the most recent public comment period for ICP emission Method 6010B. These multivariate methods are expected to be given strong consideration in the final version of the Method.

All spectroscopic interference correction techniques require that the mathematical correction models accurately reflect current wavelength axis conditions. In the case of ICP emission analyses, this is independent of whether IECs or multivariate techniques are used, and is the case for array based and non array detection. For example, if the spectral peak for an interferent occurs at one wavelength on day one and at a slightly different wavelength on day two, the interference correction models must be redefined ( or " rebuilt") to reflect these new conditions. For this reason, the true requirements for wavelength accuracy and stability are largely unrealistic.

A unique aspect of multivariate calibration is that spectral shape information is part of the correction model. By contrast, IECs employ wavelength position and relative intensities but ignore shape. Shape information provides certain advantages over IECs in terms of analytical precision, accuracy, etc., and have been presented2, 4. Of particular significance is that shape based correction models can be mathematically " shifted" ( through mathematical interpolation) once they are built. Thus, any particular wavelength condition can be accommodated. This capacity adds a number of hitherto unachievable features to ICP emission determinations. Interference correction models, and hence analytical accuracy, are independent of wavelength conditions. Furthermore, true transferability of analytical methods, leading to " turnkey" conditions, is achievable. Ultimately, the potential for transferring spectral archives between instruments, thus creating more " absolute" analytical conditions within ICP emission analyses, will be within reach.

Example data for the technique described above will be presented. This example was selected due to its strong illustration of the necessity for wavelength model coherence. The implications for this technique will also be presented and discussed.

EXPERIMENTAL A Perkin Elmer Optima 3000 DV was used for all experiments. A cross flow nebulizer ( 1 mL/ min) in a Scott type double pass spray chamber was used for sample introduction, and plasma conditions were: 0.8 mL/ min nebulizer flow; 0.5 mL/ min auxiliary flow; 15.0 mL/ min plasma flow; 1450 W power. All spectra were collected with the " normal" spectral resolution setting. For collection of the archival model spectra, slit scanning was applied for the purposes of giving data densities high enough for interpolative model shifting. Conversely, the sample data to which the models were applied was not slit scanned, as the additional data density is not required. All data were collected using ICP WinLab software operating on a Digital Pentium 100 MHz personal computer. All mathematical operations were programmed either in MatLab ( MathWorks, Natick, MA) or in Microsoft Excel ( Microsoft Corporation, Redmond, WA).

Pure component spectra ( molybdenum, chromium, vanadium) were collected by diluting and analyzing appropriate concentrations of PE Pure standard solutions. These pure component solutions were then combined to provide an appropriate test sample. All data was collected at the spectral region of the Optima detector corresponding to 270.028 270.160 nm. A wavelength monitoring solution was prepared which provided isolated lines over representative regions of the detector surface. Upon running this wavelength monitoring solution, it is possible to calculate current wavelength registration status for any and all regions of the detector surface.

RESULTS AND DISCUSSION The test sample's individual components ( each scaled to approximate equal intensity) are shown at the top of Figure 1. This combination of spectral components, particularly at the levels shown, is most useful for this demonstration since very small changes in wavelength registration can lead to significant analytical errors (> 10%). The reason for this high degree of dependence on wavelength registration is that the analyte ( vanadium) is positioned on the shoulder of interferent 1 ( chromium), which in turn is positioned on the shoulder of interferent 2 ( molybdenum), and is clearly shown at the bottom of Figure 1. Furthermore, both interferents are present at levels in great excess ( 1,000 fold) of the analyte. This spectral positioning results in an amplification of analytical error brought about by changes in wavelength registration. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 61 Figure 1. Vanadium, chromium and molybdenum components; individually and mixed.

Once the multivariate models were built with the pure spectral components, the mixed sample was analyzed and 100% recovery of the vanadium analyte was achieved. After 24 hours, the thermal conditions of the instrument were deliberately changed such that the wavelength registration was altered. The sample mixture was reanalyzed, and there was a dramatic loss in analyte recovery. At this time the degree of change in wavelength registration was measured by analyzing the wavelength monitoring solution. The pure archival spectra which make up the multivariate models were then " shifted" through interpolation, to an extent equal to that determined with the wavelength monitoring solution. For example, if the wavelength monitoring solution indicates a change in wavelength registration equal to x, then the archival component spectra are interpolatively " shifted" x. Once shifted, the multivariate models are rebuilt and used for subsequent samples. In the case of the sample described above, the shifting of the model spectra resulted in complete restoration of 100% analyte recovery. The results of these operations are shown in Table 1.

Table 1. Analytical results for vanadium in a highly interfering matrix; with and without wavelength registration compensation 100 % Induced drift, shifted models 24 hours 20 % Induced drift 24 hours 100 %  0 hours V recovery (%) Condition Time CONCLUSIONS The use of this technique shows that it is possible to perform ICP emission analyses in a manner that is independent of the wavelength axis. Provided there is a means of determining current wavelength registration status, it is possible to update multivariate calibration models to the newer status, thus eliminating wavelength registration changes as a source of miscalculation. It is then possible to have true transferability of analytical methods, as well as the possible transfer of spectral component archives.

REFERENCES 1. G. A. Laing, et al. in Proceedings: Tenth Annual Waste Testing and Quality Assurance Symposium, July 11 15, 1994, Arlington, VA. 2. J. C. Ivaldi and T. W. Barnard, Spectrochimica Acta, 1993, 48B, 1265. 3. J. C. Ivaldi and J. F. Tyson, Spectrochimica Acta, 1995, 50B, 1207. 4. J. C. Ivaldi, et al. in Proceedings: Eleventh Annual Waste Testing and Quality Assurance Symposium, July 23 28, 1995, Washington, DC. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 62 ORGANIC WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 63 WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 64 SOLID PHASE MICROEXTRACTION PREPARATIVE APPLICATIONS IN THE ANALYSIS OF ORGANIC COMPONENTS IN RADIOACTIVE WASTES John E. Young and Stephen L. Crump Westinghouse Savannah River Company, Aiken, South Carolina ABSTRACT The analytical chemistry of radioactive materials is complicated by numerous challenges. Primarily, the radiation level of material of interest may be sufficient to prohibit direct human contact. Additionally, materials used in the analysis may result in the production of mixed waste streams, which contain radionuclides in addition to hazardous wastes.

Solid Phase Microextraction ( SPME), allows preparation of aqueous radioactive samples for analysis without the introduction of hazardous solvents while simultaneously achieving bulk separation from the radioactive components in the sample.

SPME does not generate conventional extraction solvent residues which are regulated by federal and state agencies as " hazardous" wastes These solvent wastes typically require treatment by incinerators operating under state and federal operating permits. Utilization of SPME eliminates the need for an auxiliary solvent, and the subsequent need for treatment and disposal of the solvent waste stream.

Isolation of organic materials from sample matrices by traditional extraction techniques has been extensively studied and developed to optimize analyte recovery and removal of interfering components. Radioactive components in samples may make these methods inappropriate or inapplicable. Methods which require lengthy contact with the sample may be prohibitive due to radiation exposure. SPME is a technique which reduces the effects of varying sample matrices and simultaneously achieves decontamination from the inorganic radioactive components.

The advantages of SPME as a sample preparation technique for the analysis of organic constituents in radioactive wastes are summarized, with data presented on the demonstration of these advantages                                                                                SOLID PHASE EXTRACTION APPLICATIONS IN THE SAMPLING OF ORGANIC COMPONENTS IN RADIOACTIVE WASTES Stephen L. Crump, John E. Young, David T. Hobbs, and Matthew E. Jamison Westinghouse Savannah River Company, Aiken, South Carolina ABSTRACT The recent advancement and maturation of the technology used in solid phase extraction leads to new and interesting opportunities in the analytical chemistry of radioactive sample matrices. Solid phase extraction ( SPE) disks are readily applicable to the sampling of surface films in radioactive materials which must be accessed and handled remotely.

Remote sampling of unknown surface films from liquid radioactive waste storage tanks at the Savannah River Site using SPE disks has been shown to accomplish sampling objectives while reducing radiation exposure from the resulting samples.

Conventional sampling of surface films is limited by the ability to isolate the uppermost layer of the liquid into the sampling container. This inability is complicated by the hazards associated with exposures to highly radioactive materials. Sampling of these materials must be done remotely to minimize radiation exposure. Most often, this WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 65 remote handling is performed with mechanical devices such as cable activated sample grabbers, robotic instruments, or conventional " dip bucket" grab samplers.

In order to selectively sample the uppermost layer of the liquid, the sampling device must be accurately positioned to avoid collecting lower layers of the tank contents. In most applications, grab sampling is adequate to capture an adequate quantity of the surface film for analysis. However, in the case of HLW storage tank sampling, obtaining an adequate sample is extremely expensive and time consuming because of the high radiation field.

A properly conditioned SPE disk has the ability to pass through the surface film of a liquid while selectively absorbing the organic species of interest. Samples obtained by this method sorb little of the aqueous liquid phase and can be sufficiently rinsed free of most of the radioactive contaminants to allow human contact while preserving the analysts ability to characterize the organic components in the film.

Recent experiences using SPE disk sampling methods at the Savannah River Site will be presented, summarizing the potential advantages of the technique.

                                                                                A NEW PULSED FLAME PHOTOMETRIC DETECTOR FOR THE ANALYSIS OF PESTICIDES Ronald D. Snelling OI Analytical, PO Box 9010, College Station, Texas 77842 9010 ( 409) 690 1711 Many of the commonly pesticides contain sulfur, nitrogen, or phosphorus heteroatoms. In many of the pesticides more than one of the heteroatoms is present. There are a variety of detectors used to analyzed these pesticides, but all of these detectors have serious limitations. Flame photometric detectors suffer from interferences and quenching. Nitrogen  phosphorus detector have an unstable baseline and a short active element lifetime. Chemiluminescence detectors are very selective and sensitive but are complex and difficult to maintain at peak performance.

The pulsed flame photometric detector addresses these problems. The emissions from the flame are time resolved are well as wavelength resolved, so the detector is very selective. The increase in selectivity increased the sensitivity of the detector. The pulsed flame photometric detector is less affected by quenching than a conventional flame photometric detector. The detector is stable over a long period of time and requires minimum maintenance.

The pulsed flame photometric detector has dual channel data acquisition capability. Chromatograms for two different elements may be collected simultaneously from one injection and one column. This can be a very powerful tool for the confirmation of the identity of compounds containing more than one heteroatom.

The pulsed flame photometric detector offers significant advantages in selectivity, sensitivity, low maintenance, and the ability to acquire two independent chromatograms simultaneously.

                                                                                EASIER AND FASTER GC/ ECD ANALYSES OF PESTICIDES AND PCB'S Susan M. Brillante Hewlett Packard Co., 2850 Centerville Road, Wilmington, DE 19808 1610 ( 302) 633 8616 The generation of environmental data for pesticides and PCB's in various matrices can be a very time consuming process for laboratories and engineering firms. In order to keep a GC/ ECD system operating within control limits, precious analytical time must be spent on tasks such as: recalibrations, reinjection of samples, cleaning detectors, WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 66 reintegration of chromatography peaks, etc. All of these tasks take time away from running billable samples, and adversely affect the throughput or profitability of the lab.

Hewlett Packard has developed a " new" micro ECD that shows improved performance in several key areas: increased linear working range, increased sensitivity, more robust and less prone to contamination. The practical result of these features is that more GC analysis time can be spent analyzing billable samples instead of cleaning up and recalibrating the system. In addition, this detector is compatible with small id columns for fast chromatography.

Data will be presented from several laboratories to illustrate each of these features. In addition, some practical examples of how profitability ( sample throughput) can be increased by the use of fast GC will be shown.

                                                                                THE DEVELOPMENT OF AN ION CHROMATOGRAPHY METHOD TO MONITOR ORGANIC AND INORGANIC INDICATORS OF INTRINSIC BIOREMEDIATION AT HAZARDOUS WASTE SITES R. Rediske, Ph. D., A. Stiop, D. Van Dyke, Ph. D., and P. Durda Water Resources Institute, Grand Valley State University, Allendale, MI., 49401 ( 616 895 3047) ( redisker@ gvsu. edu).

ABSTRACT Many studies have demonstrated that the natural attenuation processes present at certain landfills and hazardous waste sites can effectively limit the migration of contaminant plumes. Indigenous microbial populations present in aquifer and soil systems often control contaminant migration by metabolic or co metabolic degradation mechanisms. This process is defined as intrinsic bioremediation and has been utilized as a plume management strategy at many DOD, NPL, and state hazardous waste sites. During the intrinsic bioremediation process, contaminants are degraded to CO2 and simple organic acids such as formic, acetic, and propionic. Electron acceptor compounds such as sulfate and nitrate are also involved and undergo reduction to sulfide and ammonia. The demonstration and implementation of intrinsic bioremediation depends on a comprehensive characterization of site conditions and a long term monitoring program that documents plume containment and reduction. The analysis of organic acid intermediates and electron acceptor compounds are important components of site characterization and monitoring programs.

This paper describes the development and validation of a single ion chromatography method for the analysis of low molecular weight organic acids and electron acceptor compounds in groundwater samples. Method 9056 cannot be used for all of these parameters due to limitations of the carbonate eluent. The method described uses a Dionex AS 11 column with a nonlinear sodium hydroxide gradient from 0.35 mM to 26.5 mM. Compounds analyzed by the method include: fluoride, chloride, formate, acetate, propionate, nitrate, sulfate, phosphate, pyruvate, fumarate, benzoate, and succinate. The method was validated by using deionized water, surface water, and groundwater as test matrices. Method detection limits for the compounds of interest range from 0.01 mg/ l to 0.05 mg/ l. Highly buffered groundwaters were found to interfere with the analysis of fluoride, acetate, and formate. This interference was removed by the use of a modified pretreatment resin cartridge ( Dionex OnGuard Ag   ) . A complete separation of the above analyses requires approximately 20 min.

The method was also tested on groundwater samples from a petroleum release, a landfill, and a spill of chlorinated solvents. Precision and accuracy results for MS/ MSD analyses were 70%  110%. Data for organic acids and electron acceptors were important components in the demonstration of intrinsic bioremediation at the above sites. Laboratories with ion chromatography equipment can readily implement the method. It provides similar performance to Method 9056 for common anions.

INTRODUCTION In recent years, intrinsic bioremediation has become increasingly accepted as a plume management strategy for WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 67 organic compounds dissolved in groundwater. Intrinsic bioremediation is defined as the sum of naturally occurring biodegradation, dispersion, dilution, sorption, and chemical transformation reactions that effectively reduce the toxicity, mobility, and volume of a contaminant to levels that are protective of human health and the environment1. Protocols for data collection and analysis are available for fuels, aromatic hydrocarbons, and chlorinated solvents2,3. Central to the evaluation of natural attenuation is a rigorous monitoring program that demonstrates the reduction of a contaminant and the presence of indicators that reflect the degradation process. Inorganic anions such as nitrate and sulfate are important investigative parameters as they serve as electron acceptors in the anaerobic degradation process of chlorinated and aromatic solvents4,5. These compounds are reduced to ammonia and sulfide by microorganisms during anaerobic degradation. Other anions such as fluoride and chloride can be used as conservative ions to determine diffusion and dispersion6. Low molecular weight organic acids such as acetate, formate, and propionate are also important indicators of the degradation process as they represent intermediates in the metabolic and co metabolic processes that convert organic solvents to CO2 and CH4 2,3,5. While physical/ chemical mechanisms such as volatilization, sorption, and dispersion can account for the reduction of contaminants in groundwater, the presence of organic acids provides direct evidence of the biological degradation process.

Inorganic anions can be analyzed by a variety of wet chemical and ion chromatography methods7. Ion chromatography can also be used for the measurement of low molecular weight organic acids8,9,10. The ion chromatography method listed in SW 846. Method 9025, cannot be effectively used for the determination of organic acids due to limitations of the carbonate eluent. This paper describes the development of an ion chromatography method that can be used for the simultaneous analysis of the inorganic anions and organic acids commonly measured in the demonstration of intrinsic bioremediation at hazardous waste sites. The method includes a sample pretreatment step that removes matrix interference problems related to high levels of chloride and alkalinity. Data for precision, accuracy, and method detection limit are presented along with information related to the application of ion chromatography methods to the demonstration of intrinsic bioremediation.

EXPERIMENTAL The ion chromatography method was developed on a Dionex DX 500 equipped with an electrochemical detector operated in conductivity mode. A complete description of instrumental conditions is presented in Table 1. The NaOH gradient described in the Dionex Technical Bulletin11 was modified to provide an improved separation of early and middle eluting analyses. The gradient program is described in Table 1.

A chromatogram showing the separation of the inorganic anions and organic acids is shown in Figure 1. While acceptable chromatography was obtained in samples with low alkalinity, the concentrations of carbonate and bicarbonate typically found in natural waters resulted in the loss of resolution of fluoride, acetate, formate, and propionate. The concentration of carbonate species in natural water is sufficient to change the acid/ base chemistry of the dilute NaOH eluent at the beginning of the gradient program. Carbonate also elutes as an interfering peak in the middle of the analysis. A typical chromatogram showing the effect of carbonate/ bicarbonate on the analysis of organic acids and inorganic anions is shown in Figure 2. High levels of chloride can also interfere with the analysis since this anion is often present in the 100 mg/ l range while organic acids are found at 50 µ g/ l concentrations.

In order to eliminate the interference problems related to sample alkalinity and chloride, a modified sample pretreatment system was developed. The use of pretreatment cartridges for the removal of interferences in ion chromatography has been described previously12. Cartridges are commercially available for the removal of interferences from high levels of carbonate, chloride, sulfate, and organic compounds. To remove carbonate/ bicarbonate and chloride interferences, two cartridges used in series would be required. A silver resin cartridge would first be required to remove chloride interferences. The sample would then be treated with a protonated resin cartridge to reduce the pH to 4 and be sparged with helium to remove CO2. These cartridges are generally viewed as disposable items and must be added to the cost of analysis. As a component of the development of this method, a Dionex OnGuard Ag   cartridge was modified by rinsing with a small amount of 5% nitric acid. During this process the resin becomes partially protonated while retaining some sites substituted with silver. The preparation procedure for the modified resin is described in Figure 3. Cartridges can be used for multiple injections by rinsing with 150 ml of deionized water at a rate of 10 ml/ min. It is recommended that the cartridge be regenerated after 10 samples according to the procedure outlined in Figure 3. We have noticed no degradation of cartridge performance or carry over when this sequence is followed. The performance of the modified cartridge was WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 68 compared to the Dionex OnGuard H   which functions as a protonated resin to remove carbonate interferences.

Table 1. Instrumental Conditions for the Analysis of Inorganic Anions and Organic Acids 0.2 to 10 mg/ l 0.02 to 1 mg/ l 0.02 to 1 mg/ l 0.2 to 10 mg/ l 0.02 to 1 mg/ l 0.02 to 1 mg/ l 0.02 to 1 mg/ l 0.02 to 1 mg/ l 0.05 to 5 mg/ l 0.05 to 5 mg/ l 0.02 to 1 mg/ 1 0.02 to 1 mg/ l 0.02 to 1 mg/ l Chloride Fluoride Nitrate Sulfate Phosphate Acetate Formate Propionate Benzoate Pyruvate Glutarate Succinate Fumarate Analytes ( concentration range) Dionex DX 500 Dionex ED40 Electrochemical Conductivity Mode AS 11 with AG 11 Guard ASRS 1 100 µ l 2 ml/ min NaOH 0.35 mM  26.5 mM Eluent A Deionized Water Eluent B 100 mM NaOH Eluent C 5 mM NaOH Time % A % B % C 0 min 93 0 7 2 min 93 0 7 8 min 30 0 70 20 min 7 23 70 21 min 93 0 7 Instrument Detector Column Suppressor Injection Flow Gradient For sample analysis, the modified cartridge was rinsed with 10 ml of deionized water. A 10 ml aliquot of the sample was then passed through the cartridge. The first 3 mls were discarded and the remaining 7 mls were collected in a small test tube. The treated sample was the sparged with helium at a rate of 10 ml/ min for 10 min to remove CO2. After helium sparging, the sample was ready for analysis. A five point initial calibration curve was used for quantitation. Instrument calibration was verified by the analysis of a check standard after 10 samples. Analytical standards were prepared from neat materials at the concentration ranges are listed in Table 1. A 100 µ g/ l concentration was used for MS/ MSD analysis. All standards and samples were pretreated with the modified cartridge. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 69 Figure 1. Standard chromatogram of inorganic anions and organic acids. Since the cartridge removes chloride, a separate analysis of an untreated sample is required for this parameter. Method detection limits were calculated by the analysis of 7 replicates as described in 40CFR136. Method detection limit evaluations were performed in reagent water, surface water, and groundwater. Samples from hazardous waste sites were frozen in the field using dry ice to prevent the degradation of organic acids.

Figure 2. The effect of high carbonate/ bicarbonate concentrations on early eluting inorganic anions and organic acids.

Figure 3. Preparation and regeneration sequence for modified sample pretreatment cartridges. Sequence begins with a Dionex OnGuard AG   cartridge.

RESULTS AND DISCUSSION The effects of the cartridge pretreatment on a groundwater sample spiked with organic acids is shown in Figure 4. Severe peak broadening occurs during the analysis of the untreated sample due to the interaction of the natural carbonate buffering system with the NaOH eluent. The Dionex OnGuard H   cartridge improves the resolution however; fluoride and acetate are not adequately separated. The modified cartridge provides a separation of acetate and fluoride that can be quantitated by tangent skimming algorithms. The mechanism for the improved performance of the modified cartridge has not been determined. It is possible that the addition of silver to the resin results in sites that can decompose humic materials that are common in groundwater and can also influence the resolution of early eluting compounds.

The results of method detection limit ( MDL) studies are summarized in Table 2. All analyses reported received cartridge pretreatment. With the exception of fluoride, MDLs for reagent water were comparable to results obtained in surface water and groundwater. The fluoride result was influenced by background concentrations found in the water samples. Based on the MDLs, reporting limits were set at the level of the lowest standard. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 70 Figure 4. The effect of cartridge pretreatment on the chromatographic resolution of fluoride, acetate, formate, and propionate in a groundwater sample spiked with organic acids.

Table 2. Results of the Method Detection Limit Study 0.024 0.007 0.004 0.006 0.017 0.006 0.012 0.004 0.005 0.003 0.017 0.008 0.002 0.001 0.002 0.005 0.002 0.004 0.001 0.002 0.001 0.005 0.020 0.009 0.007 0.008 0.015 0.008 0.009 0.007 0.004 0.010 0.002 0.006 0.003 0.002 0.003 0.005 0.003 0.003 0.002 0.001 0.003 0.001 0.005 0.003 0.006 0.006 0.010 0.008 0.007 0.004 0.004 0.006 0.005 0.002 0.001 0.002 0.002 0.003 0.002 0.002 0.001 0.001 0.002 0.002 0.02 mg/ l 0.02 mg/ l 0.02 mg/ l 0.02 mg/ l 0.05 mg/ l 0.02 mg/ l 0.05 mg/ l 0.02 mg/ l 0.02 mg/ l 0.02 mg/ l 0.02 mg/ l Fluoride Acetate Propionate Formate Pyruvate Nltrate Benzoate Glutarate Succinate Fumarate Phosphate MDL ( mg/ l) S. D. MDL ( mg/ l) S. D. MDL ( mg/ l) S. D. Surface Water Groundwater Reagent Water Spiked Concentration Parameter S. D. = Standard Deviation MDL = Method Detection Limit calculated from 7 replicates as described in 40CFR136.

Samples from ten hazardous waste sites were analyzed for inorganic anions and organic acids using the ion chromatography method with cartridge pretreatment. These sites represented a variety of solvent and fuel releases and a municipal solid waste landfill. The precision and accuracy results for MS/ MSD analyses performed on groundwater samples from these sites are summarized in Table 3. Duplicate precision varied from ± 12 % to ± 20 % for the target analyte list. Accuracy varied from 70% to 100% for all analyses except phosphate. During sample analysis, it was noted that high levels of ferrous iron caused the cartridge to retain phosphate. Some of the ferrous iron was retained by the cartridge, resulting in active sites that would precipitate phosphate. Samples with visible ferrous iron require the use of a freshly prepared cartridges for improved recovery of phosphate. After analysis, the cartridge must be regenerated.

Sample chromatograms for three of the hazardous waste sites are included in Figures 5, 6, and 7. The sample represented in Figure 5 was from a solid waste landfill that had groundwater plume with low levels of chlorinated solvents. Formic acid was detected in a number of wells at the site using this method. Gas chromatographic analysis detected dissolved methane in the same wells. The oxidation of methane to formic acid is the result of a microbial process that produces an enzyme that degrades chlorinated solvents3,5. These results were used along with a groundwater model to demonstrate that intrinsic bioremediation was occurring at the site and that the process was reducing and containing the chlorinated solvents in the groundwater. The sample shown in Figure 6 was from a WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 71 release of 1,1,1 trichloroethane used for parts washing. Acetate, dichloroacetic acid, and trichloroacetic acid were detected in the groundwater plume. These compounds are known microbial metabolites and chemical hydrolysis products of 1,1,1 trichloroethane4. These analytical results and groundwater modeling were used to show that the plume was contained by intrinsic bioremediation and that continued operation of the groundwater treatment system at the site was not necessary. In a similar manner, the presence of acetate and large reductions in nitrate and sulfate in the groundwater plume of a toluene release ( Figure 7) were used to show that indigenous microbial populations were actively degrading toluene in the aquifer.

Table 3. Precision and Accuracy Data for Organic Anions and Organic Acids 88 ± 12% 86 ± 15% 89 ± 11% 84 ± 14% 88 ± 10% 92 ± 10% 85 ± 12% 88 ± 14% 89 ± 15% 84 ± 12% 83 ± 15% ± 15 % ± 18 % ± 17 % ± 19 % ± 20 % ± 12 % ± 15 % ± 14 % ± 18 % ± 16 % ± 13 % 0.50 mg/ l 0.10 mg/ l 0.10 mg/ l 0.10 mg/ l 0.25 mg/ l 1.0 mg/ l 0.25 mg/ l 0.10 mg/ l 0.10 mg/ l 0.10 mg/ l 0.50 mg/ l Fluoride Acetate Propionate Formate Pyruvate Nitrate Benzoate Glutarate Succinate Fumarate Phosphate Accuracy % Recovery Precision % RPD Spiked Concentration Parameter RPD = Relative Percent Difference % RPD and % Recovery are based on the average of 10 MS/ MSD pairs SUMMARY The cartridge pretreatment step was an essential component of the ion chromatography method described in this paper. These cartridges can be regenerated and used for multiple analyses, which reduces the cost of consumables. The method yields results that are comparable with other ion chromatography and wet chemical methods for inorganic anions. It also provides data on organic acids that are useful indicators of intrinsic bioremediation. Laboratories using this method can provide a " value added" service to consultants developing intrinsic bioremediation demonstrations at hazardous waste sites.

Figure 5. Sample from a solid waste landfill. The presence of formate was used to indicate methane oxidizing bacteria which can degrade chlorinated solvents. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 72 Figure 6. Sample from a release of 1,1,1 trichloroethane. The presence of acetate, dichloroacetic acid, and trichloroacetic acid were used to demonstrate intrinsic biodegradation.

Figure 7. Sample from a toluene release. The presence of benzoate and acetate were used to document intrinsic bioremediation.

ACKNOWLEDGMENTS The authors would like to thank the NASA Space Grant Program and the Water Resources Institute for providing funding for the development of this method. We also thank Horizon Environmental and Earth Tech for providing hazardous waste site samples for analysis by this method.

REFERENCES 1. National Research Council. 1993. In situ bioremediation: When does it work? Washington, DC: National Academy Press. 2. Wiedemeier, T. H., J. T. Wilson, D. H. Kampbell, RN. Miller, and J. E. Hansen. 1995. Technical protocol for implementing intrinsic remediation with long term monitoring for natural attenuation of fuel contamination dissolved in ground water. San Antonio, TX: U. S. Air Force Center for Ennronmental Excellence. 3. Wiedemeier, T. H., M. A. Swanson, D. E. Moutoux, J. T. Wilson, D. H. Kampbell, J. E. Hansen, and P. Haas. 1996. Overview of the Technical Protocol for Natural Attenuation of Chlorinated Aliphatic Hydrocarbons in Ground Water Under Development for the U. S. Air Force Center for Environmental Excellence. in United States Environmental Protection Agency. Symposium on Natural Attenuation of Chlorinated Organics in Ground Water. EPA/ 540/ R 96/ 509. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 73 4. McCarty, P. L. 1996. Biotic and Abiotic Transformations of Chlorinated Solvents in Ground Water. in United States Environmental Protection Agency. Symposium on Natural Attenuation of Chlonnated Organics in Ground Water. EPA/ 540/ R 96/ 509. 5. Wilson, J. 1996. Natural Attenuation: Site Characterization Attenuation of Petroleum Hydrocarbons and Solvents in Ground Water. in United States Environmental Protection Agency. Bioremediation of Hazardous Waste Sites: Practical Approaches to Implementation. EPA/ 625/ K 96/ 001. 6. Bishop, D. F. 1996. Natural Attenuation of Landfills. in United States Environmental Protection Agency. Bioremediation of Hazardous Waste Sites: Practical Approaches to Implementation. EPA/ 625/ K 96/ 001. 7. USEPA. 1994. Test Methods for Evaluating Solid Waste. Physical/ Chemical Methods. SW 846. 3rd. Edition. 8. Steinmann, P., and W. Shotyk. 1995. Ion chromatography of organic rich natural waters from peatlands. III. Improvements for measuring anions and cations. J. Chromatogr. A. 706: 281 286. 9. Ammann, A., and T. Ruttimann. 1995. Simultaneous determination of small organic and inorganic anions in environmental water samples by ion exchange chromatography. J. Chromatogr. A. 706: 259 269. 10. Chen, J. 1996. Determination of organic acids in industrial streams by ion chromatography after solid phase extraction. J. Chromatogr. A. 739: 273 280. 11. Dionex. 1995. Installation Instructions and Troubleshooting Guide for the Ionpac As11 Analytical Column. Dionex Document No. 034791. 12. Henderson, I., R. Saari Nordhaus, and J. Anderson, Jr. 1991. Sample preparation for ion chromatography by solid phase extraction. J. Chromatogr. 546: 61 71.

                                                                                DETERMINATION OF CHLORINATED HYDROCARBON CONCENTRATIONS IN SOIL USING A TOTAL ORGANIC HALOGEN METHOD T. B. Lynn, Director of Research, J. C. Kneece, Intern, B. J. Meyer, Research Assistant, and A Lynn, Director of Analytical Services Dexsil Corporation, Hamden, Connecticut ABSTRACT Total organic halogen screening has been used extensively to quantify chlorinated organic compounds in soil and is the basis for a new EPA method  SW 846 Draft Method 9078 '' Screening Test Method for Polychlorinated Biphenyls ( PCB) in Soil". This method uses an organic solvent to extract the chlorinated organics from the soil and a Florisil column to remove any inorganic chloride from the extract. The extracted chlorinated organics are then reacted with metallic sodium and the resulting chloride ions are quantified using a chloride specific electrode. Using a commercially available field test kit ( the L 2000 PCB/ Chloride Analyzer   ) , the ability of this technology to measure concentrations of chlorinated pesticides and chlorinated solvents in soil was determined. The compounds investigated were: DDT, pentachlorophenol ( PCP), toxaphene, chlordane, trichloroethylene, tetrachloroethylene. The L2000 response was found to be linear over the range 0 100 ppm for all analyses and the method detection limits for these analyses ranged from a low of 2.7 ppm for Chlordane to a high of 4.8 ppm for Trichloroethylene. The average extraction efficiency varied from 39% for PCP to greater than 90% for the chlorinated solvents.

INTRODUCTION The procedure for total organic chloride analysis was originally developed for use on PCB contaminated soils and the L2000 has been used extensively since 1990 for this purpose. There is a fairly large body of data amassed demonstrating the effectiveness of the L2000 at quantifying PCB in soil1 7. The underlying principals, however, are equally applicable to other chlorinated organic compounds such as chlorinated solvents and chlorinated pesticides, most of which are regulated in some way.

The L2000 has, in fact, been used to measure other chlorinated compounds in soil. In the majority of these cases the end user has undertaken to validate the feasibility of the technology for their particular use. This validation information is usually site specific and not available to the general public. With the growing interest in the remediation of other chlorinated compounds in soil and the increase in information requests for L2000 chlorinated organics applications, we have undertaken a validation program for these applications of the L2000. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 74 The first and most important step in a total organic halogen analysis, or any chemical analysis, is the extraction of the chlorinated compounds, quantitatively, from the soil matrix. Performing this step in the field, quickly and reproducibly, on the broad range of soil matrices typically encountered is not a simple task. The solvent system must be designed to handle everything from wet clay to bone dry organic material. Unlike other field analytical methods, the organic chlorine is converted to inorganic chloride in a non aqueous solvent. ( The chloride ions are then extracted for quantification using a chloride specific electrode.) The solvent can, therefore, be easily tailored and optimized for a particular application.

The standard L2000 procedure uses a proprietary organic solvent that is polar enough to penetrate a wet clay matrix to solvate the PCB, but is itself not soluble in water. Water is added to the system to help partition the inorganic chloride into the water layer and away from the solvent layer. A Florisil column is used to remove any residual water and inorganic chloride from the extract.

This solvent/ clean up procedure has been shown to be effective at extracting PCB from most types of soils1 7. In some types of heavy clay soils with high water content, the extraction efficiency may be lowered and some of the more polar chlorinated organic compounds are removed by the Florisil column. Dexsil has developed an improved alternative two step extraction procedure that has been shown to efficiently extract PCB from wet clay soils and can also be used on polar compounds such as PCP. 8 This system uses both a polar and a non polar organic solvent combination and an aqueous/ organic solvent partition step. An optional Florisil clean up step can be added if the analyte is not one of the polar chlorinated organics such as PCP or if PCP is considered an interfering compound.

In this study all of the non polar compounds were analyzed using the standard solvent system and the alternative system was used to analyze the PCP contaminated soils. PCP was analyzed in this study using the alternative solvent system to demonstrate the flexibility of the L2000 solvent system.

Following the solvent extraction and clean up ( if necessary), the extract is reacted with metallic sodium in the presence of a catalyst. This removes the covalently bonded chlorine from the organic backbone producing chloride ions. The chloride is then extracted into an aqueous buffer and then quantified using a chloride specific electrode. The user can select a standard conversion factor for one of the typical PCB Aroclors to quantify the chloride ions as " equivalent Aroclor". The actual chlorine content of the original sample can be also be displayed. Using the chlorine content of the specific analyte, the equivalent concentration of the specific contaminant can be determined. Because the response of the instrument follows the standard Nernst equation and the quantified result is the chlorine content of the sample, any chlorinated organic compound can be quantified knowing only the percent chlorine in the compound. If the contaminant is unknown at the time of measurement, the results can later be converted using a simple linear transform, once the contaminant has been identified.

This study is the first in a series documenting the performance of the L2000 in new applications. Starting with the fundamental information required to determine if the L2000 technology is suitable for a particular application we have limited the scope of this investigation to determining: the method MDL, the range of linearity, and the extraction efficiency for a few of the most commonly encountered, regulated, chlorinated compounds. We have used laboratory spiked soils to simplify the experimental considerations.

EXPERIMENTAL Preparation of Spiked Soil Samples To ensure a consistent soil matrix throughout the spiking experiments, a large batch of composite soil was prepared prior to beginning. To simulate soils found in uncontrolled waste contaminated environments, the soil composite was prepared by mixing two types of clay and one type of sand. Each of the three soils were sifted through an 0.850 µ m sieve, and then combined in a 1: 1: 2 ratio to form the composite.

The method of spiking depended on the particular analyte characteristics. For the non polar, semi volatile compounds, DDT, toxaphene, and chlordane, a 1% stock solution in chlorine free mineral oil was prepared. PCP, being more polar, is not soluble in mineral oil; therefore, methanol was used to make up the 1% stock solution. The soils were spiked at 100 ppm by adding 5 grams of the 1% stock solutions to 500 gram aliquots in aluminum pans. The spiked soil aliquots were then slurried with hexane ( or, in the case of PCP, methanol) and allowed to evaporate WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 75 overnight in a hood space. The soils were then transferred to 16 oz glass jars and tumbled for one hour. The jars were then stored at room temperature for later use.

For each experiment, soils were prepared with the desired contaminant concentration by mixing together the correct proportions of the 100 ppm spiked soil and clean composite soil. The mixture was then tumbled for an hour prior to use.

Spiking soils with volatile solvents, uniformly and reproducibly, presented a formidable challenge. In previous work, all attempts to produce a quantity of soil, uniformly spiked, without loss of the analyte proved to be ineffective. Therefore, for the volatile solvents, trichloroethylene and tetrachloroethylene, each 10 gram soil sample was spiked, using a microliter syringe, just prior to analysis.

Method Detection Limit Determination The L2000 method detection limits for each of the chlorinated compounds were determined from replicate analysis using the method prescribed by the EPA9. An estimate of each of the detection limits was made using the concentration equivalent of three times the standard deviation of replicate measurements of the analyses in the composite soils. Soil was then spiked at the estimated detection limit. The spiking concentration for each of the chlorinated compounds are listed in Table 1 below:

Table 1. MDL Soil Spiking Concentrations 20.5 ppm 85.5 24 ppm Tetrachloroethylene 13 ppm 81.0 16 ppm Trichloroethylene 3.5 ppm 69.2 5 ppm Chlordane 3.4 ppm ~ 68 5 ppm Toxaphene 20 ppm 66.6 30 ppm PCP 2.5 ppm 50.0 5 ppm DDT Soil Chlorine Content Percent Chlorine Spiked Level Analyte Each of the spiked soils were analyzed seven times using the standard extraction method, or the alternative solvent method in the case of the PCP contaminated soils. Seven matrix blanks were also analyzed using each method. The average blank measurements were subtracted from the respective sample measurements. The MDL was then computed using the following formula:

MDL = t( n 1* 1 a = 0.99)* S where: t = the students t value S = the standard deviation of the replicate analyses The student's t value for 6 degrees of freedom at a 99% confidence interval used was 3.143. The mean recovery for each analyte was calculated by dividing the measured concentration by the theoretical concentration of analyte.

Response Curve Determination In addition to the stock soil spiked at 100 ppm, standards were prepared in the composite soil at 2, 5, 10, 20, and 50 ppm of each of the chlorinated solvents and pesticides. Standards were analyzed on the L2000 using the standard extraction method, except for PCP which was analyzed using the alternative extraction method. A reagent blank was run with each analyte. These data were then compared to analysis by gas chromatography. The extraction for the DDT, PCP, chlordane and toxaphene samples to be measured by gas chromatography at the following concentrations: 2, 5, 10, 20, 50, and 100 ppm was performed by adding three 10 mL aliquots of 1: 1 acetone hexane solvent to 5 gram aliquots of each of the spiked semivolatile soils while rinsing each soil with each addition. The solvent was then removed from the soil and run through a polypropylene filter into a 25 mL volumetric flask. The volume was filled to the mark with excess 1: 1 acetone hexane. The solvent was then transferred to another 25 mL glass test tube and capped with a teflon cap, then centrifuged to remove remaining soil particles, and WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 76 prepared for gas chromatography analysis. The extraction method used for the soils spiked with volatile analyses, trichloroethylene and tetrachloroethylene, utilized 10 mL methanol mixed with 5 grams of soil at each of the concentrations 2, 5, 10, 20, 50 and 100 ppm. The methanol was then removed from the soil and the samples were then prepared for gas chromatography. The results were then analyzed and compared to the results obtained from the L 2000 analysis.

RESULTS AND DISCUSSION Method Detection Limits The MDLs calculated from the replicate analysis of spiked soils were within the recommended range for all analyses. ( See Table 2 below). The MDLs calculated for the non polar compounds using the standard analysis method ranged from a low of 2.7 ppm for Chlordane to a high of 4.8 ppm for Trichloroethylene and 4.4 ppm for Tetrachloroethylene. The semi volatile MDLs being all lower than the MDLs for the volatile compounds. A contributing factor to the higher MDLs for the two volatile compounds was the difficulty in preparing the spiked soils. This was not unexpected, given the difficulty of working with volatile compounds in the field.

The MDL of 8.7 ppm calculated for the analysis of PCP was higher than expected. This may have been due to low extraction efficiency of the new solvent system on polar compounds. A low extraction efficiency indicates that the combination solvent was not able to penetrate the soil matrix to completely solvate the more polar PCP. In this type of a situation the analyte recovery is very sensitive to the exact handling of each sample replicate. Small changes in the shaking of the extraction tube or the length of extraction will have a larger effect on the recovery than is acceptable.

While the new solvent system facilitated the analysis of polar compounds, this sensitivity to extraction conditions is not a desirable characteristic. It produces variable results in the field and it indicates that the extraction efficiency will vary excessively with soil matrix. A second generation two step alternative solvent system has been developed8 and will be the subject of the next phase of this project.

Table 2. MDL Results 4.4 ppm* 1.3 ppm 110% 23 ppm Tetrachloroethylene 4.8 ppm* 1.54 ppm 102% 21 ppm Trichloroethylene 2.7 ppm 0.85 ppm 57% 5 ppm Chlordane 2.8 ppm 0.91 ppm 37% 5 ppm Toxaphene 8.7 ppm* 2.8 ppm 56% 30 ppm PCP 3.6 ppm 1.15 ppm 54% 5 ppm DDT Calculated MDL Replicate Standard Deviation Mean Recovery Spiked Level Analyte * Determined using the alternative extraction method. * Determined using a direct spiking method.

Response Linearity For each of the analyses investigated, the response of the L2000 using either solvent system was found to be linear over the range of concentrations studied. The resulting R2 was greater than 0.96 for all analyses. ( See Figures 1 6). This indicates that the extraction efficiency is consistent over this analyte range. The results from the L2000 can, therefore, be corrected using the known recovery. There is no indication from this data that the range of linearity is limited to 100 ppm.

Extraction Efficiency Data on the extraction efficiency of both solvent systems were obtained from the MDL determinations at a single point and from the response curve determination. The single point and the response curve determination of average extraction efficiency correlated well over the range 0 100 ppm. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 77 Table 3. Extraction Efficiency 98% 110% Tetrachloroethylene 89% 102% Trichloroethylene 70% 57% Chlordane 65% 37% Toxaphene 39% 56% PCP 52% 54% DDT Average Recovery ( from slope) MDL Mean Recovery Analyte Summary In this study it has been shown that the L2000 can be used effectively to analyze soil for chlorinated volatiles and semi volatiles. The method detection limits were shown to be in the low ppm range. This should be adequate for most contaminated sites. The response has been shown to be linear over the range of concentrations studied and a good correlation with lab methods demonstrated. A new solvent system suitable for polar organic compounds was shown to be promising. The effectiveness of a second generation two step solvent system, demonstrated in a separate study, will be the subject of phase two of this project. Furthermore, the list of suitable chlorinated compounds will be expanded and the effectiveness of the new alternative solvent system on other chlorinated compounds will be investigated. The analyte concentration range will also be extended to 2000 ppm, the upper limit on the L2000' s quantification range.

REFERENCES 1. " Case Study of a New Field Screening Tool for Delineating Soil PCB Contamination", Mark B. Williams, PE and John S. Flickinger Dames & Moore ( Madison, WI), Joseph E. Shefchek, CHMM Wisconsin Power & Light ( Madison, WI), E. Jonathan Jackson, CHMM Haliburton NUS Environmental Corp. ( Aiken, SC); Proceedings: 1991 EPRI PCB Seminar. 2. " PCB Determination, Simple/ Low Cost or Complex/ Expensive, Which Method is the Most Reliable in the Field?", S. Finch, pp. 45 1 to 45 4; Proceedings: 1991 EPRI PCB Seminar 3. " Application of a New PCB Field Analysis Technique for Site Assessment", Roger D. Griffin Griffin Environmental; Proceedings of Hazmacon ' 92 March 1992. 4. " A Comparison of Popular Field Screening Methods for PCB Contamination in Soil", Alvia Gaskill Environmental Reference Materials, 1993 EPRI PCB Seminar. 5. " Comparison of the Response of PCB Test Methods to Different PCB Aroclors", Stephen Finch Dexsil Corporation Proceedings of " The Tenth Annual Waste Testing and Quality Assurance Symposium July 11 15, 1994 Arlington, VA.

Figure 1. Response Curve for DDT WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 78 6. " Effect of Transformer Oil & Petroleum Hydrocarbons as Interferences in Field Screening for PCB Contamination of Soil", Alvia Gaskill; Proceedings of " The Tenth Annual Waste Testing and Quality Assurance Symposium", July 11 15, 1994 Arlington, VA. 7. " Accurate On Site Analysis of PCBs in Soil, A Low Cost Approach", Deborah Lavigne Dexsil Corporation. 8. " Improved Extraction Efficency of Polychlorinated Biphenyls from Contaminated Soil Using a total Halogen Screening Method, W. S. Schutt Young, A. C. Lynn, T. B. Lynn, M. J. Krumenacher, Manuscript Submitted 9. Definition and Procedure for the Determination of the Method Detection Limit, Environmental Protection Agency Publication, 40 CFR Ch. 1 ( 7 1 89 Edition), Appendix B, part 136, 525 527 Figure 2. Response Curve for PCP Figure 3. Response Curve for Toxaphene WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 79 Figure 4. Response Curve for Chlordane Figure 5. Response Curve for Trichloroethylene WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 80 Figure 6. Response Curve for Tetrachloroethylene                                                                                A FIELD USEABLE METHOD FOR TOXICITY SCREENING OF WASTE STREAMS GENERATED DURING DESTRUCTION OF CHEMICAL WARFARE AGENTS Theresa R. Connell and Kevin M. Morrissey SciTech Services, Inc., 1311 Continental Drive, Suite G, Abingdon, Maryland 21009 Tel: ( 410) 671 7104/ Fax: ( 410) 676 2304 E mail: opsmgr@ scitechinc. com H. DuPont Durst US Army, CBDCOM, Edgewood Research, Development, and Engineering Center, Edgewood, Maryland 21009 Tel: ( 410) 671 5270/ Fax: ( 410) 671 2081 E mail: hddurst@ cbdcom. apgea. army. mil A program to chemically neutralize chemical warfare agents ( CWA) was carried out, and involved the neutralization of bis( 2 chloroethyl) sulfide ( HD) with monoethanolamine: water solutions. This program supports an effort to develop and deploy field transportable systems which can destroy CWA recovered from small burial sites. To ensure operator safety and completeness of destruction, a fieldable second tier screening method was required to estimate toxicity levels of the resulting reaction masses. This second tier screening is in addition to conventional GC/ MSD methods for quantitation of residual CWA. In this case, the toxicity characteristic of the HD was its vesiccant, or alkylating capacity.

Alkylating capacity is defined as those compounds which react with 4( 4 nitrobenzyl) pyridine ( 4 NBP), and yield a product which absorbs in the range of 536 to 546 nm. Alkylating capacity is expressed as µ moles of alkylating sites per liter of sample, or µ M. Quantitation is accomplished using a UV/ Vis spectrophotometer, with external standard calibration. The method was determined to have a linear range of 98.7 to 987 µ M of alkylating capacity, with the response beginning to exhibit non linear behavior after approximately 1000 µ M of alkylating capacity.

The use of 4 NBP for the detection of alkylating agents is well documented, and has been extensively reviewed. The method presented here has been optimized for a particular sample matrix, and consists of reaction of 4 NBP with acidified ( pH 4 to 5) sample to form a dye precursor. The solution is then made basic with K2CO3 to generate a final product with an absorption maxima at approximately 540 nm. The reaction product is then extracted into 2M isopropylamine in toluene, and alkylating capacity is quantitatively estimated using standard methods of colorimetric analysis. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 81 The analytical parameters were optimized with respect to acid type, base type, extraction solvent, reagent amounts, and heating time. Parameter selection was based on that value which gave a maximum absorbance and a minimum relative standard deviation. Examples of optimization experiments will be presented. In addition, results from experiments evaluating spiking procedure, response of method to other alkylating agents, and stability of reaction product will also be presented.

The method was validated by spiking and analyzing seven replicates at each of four spike levels. All four spike levels were performed in simulated matrix, and one spike level was also performed in an actual sample. There was not a significant difference in percent recoveries when the spike was performed in simulated matrix or an actual sample. The average percent recovery at 537 µ M alkylating capacity was 102% ( n= 14, CV = 11.7%). The method limits of detection and quantitation will be discussed.

The method was used to evaluate three independent reactor runs, and gave consistent patterns for each kinetic series within a reactor run. In addition, a sample was monitored for approximately 90 hours after reactor drain to follow the continued breakdown of HD. Parallel analyses using the standard GC/ MSD methods were also conducted. Results from both sets of analyses will be presented and compared.

                                                                                DETERMINATION OF OIL CONTENT OF CONTAMINATED SOILS AND SLUDGES Abdul Majid, and Bryan D. Sparks Institute for Chemical Process and Environmental Technology, National Research Council of Canada, Ottawa, Ontario K1A 0R9 ABSTRACT This paper reports potential applications of liquid phase agglomeration techniques in the removal of oil from contaminated soil and sediment samples for subsequent quantitative measurements. The use of liquid phase agglomeration techniques greatly improves the efficiency of solids solvent separation. As a result, better contaminant recoveries were achieved in a shorter period of time compared with the conventional Soxhlet  Dean and Stark solvent extraction method. Quantitative determination of the contaminant was carried out using gas chromatographic and spectrophotometric methods. Two case studies are discussed. The first deals with the quantitative determination of diesel fuel from a contaminated diesel invert drilling mud sample. The second evaluates the extraction and subsequent quantification of heavy oil from a contaminated soil sample The objective of this study was to develop a quick and efficient procedure for the extraction and subsequent quantification of total petroleum hydrocarbons in contaminated wastes. The proposed method can be adapted to the extraction and subsequent quantification of a variety of hydrocarbon pollutants from contaminated soils and sediments.

INTRODUCTION Both the design and planning of a soil reclamation program and the evaluation of disposal, reprocessing or reclamation options for sludges, oily wastes and tailings depend upon a reliable and accurate means of evaluating the total oil content of polluted soils. A precise estimate of the amount of hydrocarbons is essential to determine the extent of contamination and the success of the reclamation program. Treatment technologies and site remediation progress lean heavily on analytical techniques that are accurate, reproducible and of real time value. Current analytical methods are inadequate because of the following concerns:

w The recovery of oil from contaminated samples is influenced by the sample preparation method and the oil extraction methods. w The solvent extraction methods, used to remove oil from contaminated samples for subsequent measurements, have limitations with respect to the water content of the sample and the particle size distribution of the matrix. Usually these methods are less efficient for fine textured materials. Also, water is known to reduce the extraction efficiency of organic solvents because of the formation of oil in water emulsions1 2. w Loss of volatile organics, during solvent removal for sample concentration, results in significant bias. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 82 w Spectroscopic determination of contaminants has the disadvantage that degradation of pollutants in the soil results in altered spectral characteristics. Absorbance at certain wavelengths may increase with time even though the total amount of oil in the soil would be decreasing. Also, in clay soils where oil components may be absorbed, spectral properties of the extracted oil may also change1. w A wide variety of laboratory techniques used to measure TPH provide data of varying quality.

In our previous work we demonstrated the potential applications of proton NMR in the quantitative determination of bitumen and solvents extracted from oil sands and fine tailings3 4. The NMR method can be used to estimate the amount of any residual solvent in the oil. The retention of low boiling components, normally lost during solvent removal, produces a more representative sample of the oil for calibration purposes.

Liquid phase agglomeration techniques, in combination with solvent extraction have been successfully used for the removal of hydrocarbon contaminants from fine textured, organic contaminated soils5. Agglomeration of fines with the coarse particles is achieved by the addition of water to a vigorously mixed slurry of soil in the selected solvent. Water acts as a solids bridging liquid and dense soil agglomerates are formed under appropriate conditions. The bridging liquid remains in the agglomerate pores where interfacial tension provides the forces holding the aggregates together. Judicious selection of agglomerate size, by controlling water content, greatly improves the efficiency of solids solvent separation.

The objective of this study was to explore the use of liquid phase agglomeration techniques in the development of a more efficient solvent extraction procedure. Two hydrocarbon contaminants, one associated with a fine textured soil and the other with a coarser matrix, were selected for subsequent quantitative measurements.

EXPERIMENTAL Samples. One of the samples used for this study was a used Diesel Invert Drilling Mud ( DIDM) from Alberta. This sample contained over 70 w/ w% of solids < 41 µ m diameter. The diesel content of this sample was estimated by extraction with toluene using the Dean and Stark Soxhlet method6. The extract was characterized and subsequently quantitated by GC. The GC chromatogram of the extract was a good match with the chromatogram for a sample of diesel obtained from a local gas station in the summer of 1995. This commercial diesel sample was used for preparing calibration standards.

The second sample used in this study was a highly saline soil sample provided courtesy of Newalta Corporation, Calgary, Alberta. It was a mixture of tank bottoms, frac sand and spill material containing a range of organic and inorganic contaminants. The organic contaminant in this sample was a high boiling heavy oil.

Proton NMR measurements. Proton NMR measurements were performed on a Brucker AM 400 NMR spectrometer ( 400 MHz); 500 µ L of solution in a 5 mm outer diameter tube was used in each case. A repetition time of 2 seconds was selected. Each spectrum was the Fourier transform of 1000 free induction decay curves. Once adjusted all parameters were kept constant for subsequent measurements.

GC determination of diesel. The extract was analyzed employing a Varian Model 3300 GC equipped with an FID detector and a temperature gradient program. A DB 5, megabore, capillary column, 30 meters in length with a 0.53 mm internal diameter and a 1.5 micron film thickness ( J & W Scientific) was used. The initial operating temperature was 50 degrees Celsius with an initial hold time of 5 minutes. The temperature was then increased at the rate of 10 degrees per minute to a final temperature of 300 degrees Celsius where it was held for 5 minutes. Calibration curves were prepared using the purchased sample of # 2 Diesel Fuel.

Soxhlet Dean and Stark Method. The extraction of heavy oil from the Newalta sample was carried out for 20 hours using the Soxhlet Dean and Stark method6. Both toluene and methylene chloride were used separately for extraction.

Spectrophotometric estimation of heavy oil. The quantitation of the oil component was carried out using a spectrophotometric method7 based on the linear relationship between the absorbance at 530 nm and the concentration of oil in solution. WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 83 For calibration purpose oil samples were obtained from a methylene chloride extract of the soil. Non filterable solids were removed from the oil extract by centrifugation. The solvent was removed at 40 ° C in a Brinkmann rotary evaporator under reduced pressure. The amount of residual solvent in the oil was quantitatively measured using proton NMR4. A correction for solvent content was applied to the amount of oil used in the preparation of standard solutions. For spectrophotometric measurements, absorbances at 530 nm were determined for toluene solutions of the oil for concentrations ranging from 0.01  0.4 w/ w%. Plots of the percent oil vs. absorbance produced a straight line passing through the origin.

Liquid Phase Agglomeration Procedure. In a typical test a polypropylene Waring Blendor Jar ( 500mL), equipped with Teflon washers and a plastic cover, was accurately weighed. To the jar were added: contaminated solids ( 20g), and solvent ( 50mL). The contents were agitated at high shear for 1 minute. The solution was carefully drained into another 500 mL polypropylene jar. About 1w/ w% of an additive ( sodium meta phosphate, calcium hydroxide or scrubber sludge), additional water and fresh solvent ( 50 mL) were added to the original Blendor jar still containing the extracted solids from the primary extraction. The contents were agitated at high shear for 1 minute followed by 5 10 minutes at low shear until the slurry became clear as discrete agglomerates were formed. The supernatant solution from the second treatment was drained into the polypropylene jar containing solution from the primary extraction. The procedure was repeated three more times and all extracts were combined. The extracted solids were surface washed and the washings were added to the solution in the polypropylene bottle. The contents of the bottle were centrifuged and the clear solution was transferred to a 500 mL glass measuring flask. The residue in the polypropylene bottle was agitated with fresh solvent and then centrifuged. The solution was combined with the solution in the measuring flask. The procedure was repeated until the washings became colorless. The solution in the measuring flask was made up to the mark. The amount of oil was estimated in this solution using the spectrophotometric method.

RESULTS AND DISCUSSION The Amount of Extractable Oil from Contaminated Solids The extraction of diesel from a used diesel invert mud sample and a heavy oil from Newalta contaminated soil sample were carried out using both the conventional Dean & Stark Soxhlet and Solvent Extraction Soil Agglomeration ( SESA) methods. Subsequent quantification was carried out using GC/ FID for the diesel and spectrophotometric method for the heavy oil. The results are summarized in the Table. It is obvious from the results that not only better recoveries of the contaminants were obtained using the SESA method but the total turn around time was also much reduced.

13.38 ± 0.49 ( 3) 4.99 ± 0.22 ( 3) 2 SESA** 12.9 ± 0.2 ( 5) 4.84 ± 0.1 ( 5) 21 Dean & Stark Soxhlet Method NEWALTA DIDM*** Amount of oil extracted ( g/ 100g of wet solids)* Extraction plus analysis turn around time ( Hrs) Method * Figures in parenthesis represent number of tests carried out. ** Solvent Extraction Soil Agglomeration process. *** Diesel Invert Drilling Mud sample CONCLUSION Liquid phase agglomeration has potential for use as a quick and efficient analytical procedure for the extraction and subsequent quantification of a variety of petroleum contaminants from contaminated wastes.

REFERENCES 1. McGill, W. B., and Rowell, M. J., " Determination of Oil content of oil contaminated Soil'" The Science of the Total Environment, 14, 245 253 ( 1980). 2. Doldson, S. G., Miller, G. C., and Miller, W. W., " Extraction of Gasoline Constituents from Soil,", Journal Association of Official Analytical Chemists, 73, No. 2, 306 311 ( 1990), 3. Majid, A. and Woods, J., " Rapid determination of Bitumen, Varsol and other Solvents using Proton NMR", WTQA ' 97  13th Annual Waste Testing & Quality Assurance Symposium 84 Preprints ACS Div. Fuel Chem. 28, 188 195 ( 1983). 4. Majid, A. and Sparks, B. D., " Total Analysis of Mineral Wastes Containing Bitumen, Solvent, Water and Solids", AOSTRA J Res. 1, 21 29 ( 1984). 5. Meadus, F. W., Sparks, B. D. and Majid, A., " Solvent Extraction Using a Soil Agglomeration Approach", Emerging Technologies in, " Hazardous Waste Management Vl", Editors: D. William Tedder and Frederick G. Pohland, American Chemical Society, Chapter 11, pages 161 176 ( 1996) 6. Syncrude analytical methods for oil sand and bitumen processing, J. T. Bulmer and J. Star Editors. Alberta oil Sands Information Centre, Edmonton, AB, pp. 46 51 ( 1979). 7. Patel, M. S., " Rapid and Convenient Laboratory Method for Extraction and Subsequent Spectrophotometric Determination of Bitumen Content of Bituminious Sands"; Anal. Chem. 46, 794 ( 1974).

                                                                                IMPROVED EXTRACTION EFFICIENCY OF POLYCHLORINATED BIPHENYLS FROM CONTAMINATED SOIL USING A TOTAL HALOGEN SCREENING METHOD W. S. Schutt Young, Ph. D., Application Specialist; A. C. Lynn, Director of Laboratory Services; T. B. Lynn, Ph. D., Director of Research; B. J. Meyer, Research Assistant Dexsil Corporation, One Hamden Park Drive, Hamden, Connecticut 06517. M. J. Krumenacher, P. G., CPG, CGWP, CHMM, Hydrogeologist/ Senior Project Manager GZA GeoEnvironmental, Inc., N4140 Duplainville Road, Pewaukee, Wisconsin 53072.