[Federal Register Volume 78, Number 128 (Wednesday, July 3, 2013)]
[Rules and Regulations]
[Pages 40000-40011]
[FR Doc No: 2013-15880]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 50

[EPA-HQ-OAR-2012-0210; FRL-9822-1]
RIN 2060-AP89

Method for the Determination of Lead in Total Suspended
Particulate Matter

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The EPA is establishing a new Federal Reference Method (FRM)
for measuring Lead (Pb) in total suspended particulate matter (TSP)
collected from ambient air. This method is intended for use by
analytical laboratories performing the analysis of Pb in TSP to support
data collection for the Pb National Ambient Air Quality Standard
(NAAQS). The existing FRM for Pb is designated as a new Federal
Equivalent Method (FEM), and the currently designated FEMs are
retained. This action avoids any disruption to existing Pb monitoring
networks and data collection and does not affect the FRM

for TSP sample collection (High-Volume Method).

DATES: This final rule is effective on August 2, 2013.

ADDRESSES: The EPA has established a docket for this action under
Docket No. EPA-HQ-OAR-2012-0210. All documents in the docket are listed
on the www.regulations.gov Web site. Although listed in the index, some
information is not publicly available, e.g., Confidential Business
Information (CBI) or other information whose disclosure is restricted
by statute. Certain other material, such as copyrighted material, is
not placed on the Internet and will be publicly available only in hard
copy form. Publicly available docket materials are available either
electronically at www.regulations.gov or in hard copy at the Air
Docket, EPA/DC, EPA West, Room 3334, 1301 Constitution Avenue NW.,
Washington, DC. The Air Docket and the Public Reading Room are open
from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal
holidays. The telephone number for the Public Reading Room is (202)
566-1744, and the telephone number for the Air Docket is (202) 566-
1742. For additional information about EPA's public docket visit the
EPA Docket Center homepage at: http://www.epa.gov/epahome/dockets.htm.

FOR FURTHER INFORMATION CONTACT: Ms. Joann Rice, Office of Air Quality
Planning and Standards, Air Quality Assessment Division, Ambient Air
Monitoring Group (C304-06), U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina 27711; telephone number: (919)
541-3372; fax number:<PHONE_NUMBER>; email address:
<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

Table of Contents

I. Background
    A. Purpose of the New Reference Method
    B. Rationale for Selection of the New Reference Method
    C. Comments on the Proposed Rule
    D. Conclusions
II. Summary of Method
III. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions to Address
Environmental Justice in Minority Populations and Low-Income
Populations
    K. Congressional Review Act

I. Background

A. Purpose of the New Reference Method

    On November 12, 2008, the EPA substantially strengthened the NAAQS
for Pb (73 FR 66964). The EPA revised the level of the primary (health-
based) standard from 1.5 micrograms per cubic meter ([mu]g/m\3\) of Pb
to 0.15 [mu]g/m\3\ of Pb measured in TSP and revised the secondary
(welfare-based) standard to be identical in all respects to the primary
standard. The current Pb in TSP FRM is based on Flame Atomic Absorption
Spectroscopy (FAAS) as specified in 40 CFR part 50, Appendix G. The FRM
in Appendix G was originally promulgated in 1978 when FAAS was widely
used and considered the best available method to support Pb NAAQS data
collection at a level of 1.5 [mu]g/m\3\. A new Pb in TSP FRM is needed
to: (1) Take advantage of improved extraction methods that are now
available with improved precision, sample throughput, and extraction
efficiency; (2) address advances in measurement technology that have
occurred since promulgation of the original FRM; and (3) address the
improved measurement sensitivity (detection limits) needed in response
to the tightened Pb NAAQS.
    The reference method for Pb in TSP includes two parts: the analysis
method for Pb in TSP as specified in 40 CFR 50, Appendix G, and the
reference method for high-volume sampling of TSP as specified in 40 CFR
50, Appendix B. The new FRM is for the analysis of Pb in TSP based on
Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The FRM serves
as the definitive method for routinely analyzing Pb for comparison to
the NAAQS and also serves as the standard of comparison for determining
equivalence of candidate FEMs. This method replaces the existing method
in 40 CFR 50, Appendix G. The FRM that was promulgated in 1978 as
Appendix G becomes an approved FEM and the currently designated FEMs
are retained. The EPA believes this is appropriate because the new FRM
is based on two methods that were tested and approved as FEMs (EQL-
0510-191 and EQL-0710-192) to ensure comparability with the FAAS
method. This approach permits continued use of the legacy FRM (as an
FEM) and the existing FEMs. This avoids any disruption to state and
local air monitoring agencies using these methods for Pb monitoring.
The reference method for high volume sampling of TSP will continue to
be performed in accordance with the FRM described in Appendix B, and,
therefore, is not included as part of this FRM.
    With the tightened NAAQS in 2008 and the need for increased
measurement sensitivity, an improved measurement technology has become
available to meet the needs of the current NAAQS. The FAAS method is
less frequently used in the Pb ambient monitoring network (about 10
percent of the sites reported Pb in TSP data to the EPA's Air Quality
System in 2012 using the FAAS method) and ICP-based methods have
increased in popularity. Recently, the FAAS method has mainly been used
as the reference method for testing and designation of candidate FEMs
for Pb in accordance with 40 CFR 53.33. With the lowered Pb
concentration testing range in Part 53 and new requirement for a Method
Detection Limit (MDL) of 0.0075 [mu]g/m\3\ (described below), the FAAS
method sensitivity and availability of laboratories with FAAS
capability have created some challenges for comparability testing of
new FEMs.
    In 2008, the EPA also revised the performance-based requirements
for Pb FEMs in Part 53. The performance requirements were revised to be
consistent with the revised Pb NAAQS level. Specifically, the Pb
concentration range at which the FEM comparability testing is conducted
was lowered to a range of 0.045 to 0.375 [mu]g/m\3\ and the requirement
for a minimum method detection limit was established at 0.0075 [mu]g/
m\3\. The detection limit of the new FRM is more than adequate to meet
the reduced testing range and detection limit requirements. The FRM's
average detection limit for Pb-spiked filters is estimated at 0.00009
[mu]g/m\3\, which is well below the requirement of 0.0075 [mu]g/m\3\.

B. Rationale for Selection of the New Reference Method

    The FRM is based on two recently approved FEMs for extracting Pb
from glass fiber filters for subsequent analysis by ICP-MS: (1) Method
EQL-0510-191 which uses a heated (80  5[deg]C) ultrasonic
water bath with 1.03M nitric (HNO3)/2.23M hydrochloric (HCl)
acids, and (2) Method EQL-0710-192 which uses a heated (95
5[deg]C) graphite block (hot block) with 3.5 percent volume/

volume (v/v) HNO3. In selecting this methodology, the EPA's
primary considerations were: methods that have already been tested and
approved against the FAAS method; use of equipment that is commonly
used; a method that is practical (use of a single vessel for the entire
extraction process and storage); and a method with improved sensitivity
and throughput to increase efficiency and cost effectiveness over the
legacy FRM. ICP-MS was chosen as the analytical technique because it
has improved sensitivity, selectivity, linear range, and is more
readily available than FAAS in laboratories today.
    The FRM uses methods from two existing FEMs that have been proven
comparable to FAAS and, therefore, retains consistency with the legacy
FRM (Rice, 2013). The FRM is only intended for the analysis of Pb in
TSP and allows for the use of glass fiber, quartz, or
polytetrafluoroethylene (PTFE) filters. HNO3 alone is
sufficient for the extraction of Pb; however, the ultrasonic extraction
method includes HCl to allow monitoring agencies some flexibility for
future needs that may include the extraction of other metals. HCl is
needed to aid the extraction of other metals that are not easily
brought into solution with HNO3 alone. The FRM was evaluated
for the extraction of Pb only. If the FRM is used for metals other than
Pb, the user must evaluate the FRM's applicability before use. The hot
block extraction method uses only HNO3 and must also be
evaluated by the user before use to extract metals other than Pb.
    The approach and key specifications of the method were submitted
for peer review to the Clean Air Scientific Advisory Committee (CASAC)
Ambient Air Monitoring and Methods Subcommittee. Public meetings were
held to discuss the method and related monitoring issues on September
15, 2010. Comments on the method and approach were provided in writing
in a letter dated November 30, 2010 (EPA-CASAC-11-002),\1\ forwarded by
CASAC to the Administrator.
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    \1\ CASAC's final report on the Approach for the Development of
a New Federal Reference Method (FRM) for Lead in Total Suspended
Particulates (Pb-TSP) can be found at: http://yosemite.epa.gov/sab/
sabproduct.nsf/DA39026E54BAF46E8525781D00606633/$File/EPA-CASAC-11-
002-unsigned.pdf.
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    The CASAC was supportive of the ICP-MS analytical method and found
the approach to be appropriate with superior sensitivity and
specificity for Pb. The CASAC recommended a strategy, using a
performance-based FRM, to provide flexibility for use of non-FRM or FEM
measurement methods and recommended that a third extraction method
(microwave) be added to the FRM for its greater sample throughput and
potential for reduced sample-to-sample variability. The CASAC viewed
the comprehensiveness of the FRM test plan to be appropriate, and
recommended that the EPA consider separating the extraction methods
from the analytical methods so that any of the FRM extraction methods
can be used with any of the FRM analytical measurement methods.
    The federal reference and equivalence testing method for Pb in 40
CFR 53.33 serves as the performance-based method approach for the FEM
approval process. Candidate methods are tested using the performance
specifications of part 40 CFR part 53 for acceptance and approval as
equivalent methods. Users also have the flexibility to test and submit
additional extraction and analysis methods for review and approval as
equivalent methods. The EPA believes that microwave extraction is a
viable option and is already available as an approved FEM.\2\ The
ultrasonic and hot block approaches are sufficient for the extraction
of Pb and provide high sample throughput, low consumable costs, and
lower equipment costs while minimizing the risk of cross contamination
and sample loss. In addition, the EPA believes that the existing FEMs
\3\ currently provide a wide variety of extraction and analytical
methods and the EPA strongly encourages monitoring agencies to consider
adopting one of the already approved FEMs in lieu of submitting new FEM
applications. The FRM has two extraction methods (heated ultrasonic and
hot block) and one analytical method (ICP-MS). The FRM allows for the
use of either of the two extraction methods specified with the ICP-MS
analytical method. The method also allows for the use of glass fiber,
PTFE, or quartz filter media for the collection of Pb in TSP.
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    \2\ FEM EQL-0400-0140 (65 FR 26603, May 8, 2000).
    \3\ The list of current FEMs is located at: http://epa.gov/ttn/amtic/files/ambient/criteria/reference-equivalent-methods-list.pdf.
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C. Comments on the Proposed Rule

    On February 5, 2013, the EPA proposed a new FRM for determination
of Pb in TSP (78 FR 8066) and solicited comment on the proposed method.
The EPA received one public comment by the close of the public comment
period on March 7, 2013. The commenter questioned the meaning of the
MDLs estimated from the analysis of blanks. The commenter recommended
that an MDL estimated from blanks include the mean of the blanks and be
consistent with the Report of the Federal Advisory Committee on
Detection and Quantitation (FACDQ) Approaches and Uses in Clean Water
Act Programs (FACDQ, 2007). The Federal Advisory Committee recommended
that EPA adopt a new procedure for estimated method sensitivity and
replace 40 CFR 136, Appendix B (Definition and Procedure for the
Determination of the Method Detection Limit) with the new procedure.
The FACDQ procedure described an approach for calculating MDLs and
quantitation limits. The EPA conducted a pilot study to assess whether
the procedure recommended by the FACDQ could generate reliable
estimates of the lowest concentration at which measurement quality
objectives could be achieved (U.S. EPA, 2011). Based on the pilot study
results, the EPA concluded that none of the procedures tested
consistently generated accurate estimates of the lowest concentration
at which the study measurement quality objectives were achieved. The
EPA believes that more development and testing of the FACDQ procedure
are warranted.\4\ Accordingly, based on the currently available
information, the EPA believes that the procedures identified in 40 CFR
135, Appendix B are a more appropriate basis for estimating MDLs for
the FRM.
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    \4\ Refer to: http://water.epa.gov/scitech/methods/cwa/det/index.cfm for EPA's Procedures for Detection and Quantitation.
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    The EPA provided estimates in the proposed rule for MDLs based on
reagent/filter blanks and reagent/filter blanks spiked with a Pb
solution. The EPA estimated MDLs based on 40 CFR 136, Appendix B which
recommends that MDLs be determined using a concentration value that is
between 1 and 5 times the estimated MDL. However, 40 CFR 136, Appendix
B does not specify the use of reagent/filter blanks for estimating the
detection limit. The estimate of MDLs based on reagent/filter blanks is
not consistent with 40 CFR 136, Appendix B; therefore, the MDL
estimates from reagent/filter blanks have been removed. The remaining
MDL estimates in Tables 1, 3, and 5 were determined using reagent/
filter blanks that were spiked with Pb at three times the estimated
detection limit of 0.001 [mu]g/mL. The MDLs were estimated to
demonstrate method performance that is more than adequate to meet the
MDL requirements of 0.0075 [mu]g/m\3\ for Pb in TSP. It is recommended
that laboratories performing this method initially estimate MDLs in
accordance with 40 CFR Part 136, Appendix B and

confirm the MDLs annually. In addition, the EPA recommends that
laboratories consider performing the optional iterative procedure in
Part 136, Appendix B to verify the reasonableness of the initially
estimated MDL and subsequent MDL determinations.

D. Conclusions

    After consideration of the public comment on the estimate of MDL
from reagent/filter blanks, the EPA has concluded that the rule should
be consistent with the provisions of 40 CFR Part 136, Appendix B.
Accordingly, any language referring to the estimate of MDLs using
reagent/filter blanks and the MDLs estimated from reagent/filter blanks
in Tables 1, 3, and 5 have been removed. The MDLs estimated from the
Pb-spiked reagent/filter blanks remain and demonstrate that the method
has more than adequate sensitivity to support the Pb-TSP MDL
requirement of 0.0075 [mu]g/m\3\. No other comments were received nor
revisions made to the proposed rule. The rule is otherwise finalized as
proposed.

II. Summary of Method

    The FRM uses the ambient air sample collection procedures of the
high-volume TSP method (40 CFR Part 50, Appendix B) and the analytical
procedure for the measurement of Pb based on ICP-MS. Two extraction
methods are used: One using heated ultrasonic and one using hot block
digestion. The extraction methods and ICP-MS analysis method have been
tested and found acceptable for extraction of Pb from glass fiber,
PTFE, or quartz filter media. This method also met the precision and
bias goals for Pb in TSP (Rice 2013). This method replaces the previous
FRM specified in 40 CFR Part 50, Appendix G. Although the previous FRM
in Appendix G is adequate, this method offers advantages over the
previous FRM by providing improved sensitivity or detection limits,
precision, sample throughput, and extraction efficiency.

III. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

    This action is not a ``significant regulatory action'' under the
terms of Executive Order 12866 (58 FR 51735, October 4, 1993) and is,
therefore, not subject to review under Executive Orders 12866 and 13563
(76 FR 3821, January 21, 2011).

B. Paperwork Reduction Act

    This action does not impose an information collection burden under
the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq.
Burden is defined at 5 CFR 1320.3(b). This rule is to promulgate a new
FRM for Pb in TSP, and to designate the existing FRM as an FEM, and
does not add any information collection requirements beyond those
imposed by the existing Pb monitoring requirements.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative
Procedure Act or any other statute unless the agency certifies that the
rule will not have a significant economic impact on a substantial
number of small entities. Small entities include small businesses,
small organizations, and small governmental jurisdictions.
    For purposes of assessing the impacts of this rule on small
entities, small entity is defined as (1) a small business as defined by
the Small Business Administration's (SBA) regulations at 13 CFR
121.201; (2) a small governmental jurisdiction that is a government of
a city, county, town, school district or special district with a
population of less than 50,000; and (3) a small organization that is
any not-for-profit enterprise which is independently owned and operated
and is not dominant in its field.
    After considering the economic impacts of this rule on small
entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities. This rule
will not impose any additional monitoring requirements beyond those
specified in the current regulations, nor will it require any changes
in approved monitoring methods. As such, it will not impose any
requirements on small entities.

D. Unfunded Mandates Reform Act

    This action contains no federal mandates under the provisions of
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), 2 U.S.C.
1531-1538 for state, local, or tribal governments or the private
sector. This action imposes no enforceable duty on any state, local or
tribal governments or the private sector. Therefore, this action is not
subject to the requirements of sections 202 or 205 of the UMRA. This
action is also not subject to the requirements of section 203 of UMRA
because it contains no regulatory requirements that might significantly
or uniquely affect small governments. This action establishes a new FRM
for state and local air monitoring agencies to use as one of the
approved methods for measurement of Pb in TSP and to designate the
existing FRM as an FEM. It does not create any additional monitoring
requirements or require changes in approved monitoring methods.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government, as
specified in Executive Order 13132. This action establishes a new FRM
for state and local air monitoring agencies to use as one of the
approved methods for measurement of Pb in TSP and designates the
existing FRM as an FEM. This action does not create any new monitoring
requirements or require any changes in approved monitoring methods.
Thus, Executive Order 13132 does not apply to this action.

F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

    This action does not have tribal implications, as specified in
Executive Order 13175 (65 FR 67249, November 9, 2000). This rule
imposes no requirements on tribal governments. This action establishes
a new FRM for state and local air monitoring agencies to use as one of
the approved methods for measurement of Pb in TSP and designates the
existing FRM as an FEM. This action does not create any new monitoring
requirements, nor require any changes in approved monitoring methods.
Thus, Executive Order 13175 does not apply to this action.

G. Executive Order 13045: Protection of Children From Environmental
Health and Safety Risks

    The EPA interprets EO 13045 (62 F.R. 19885, April 23, 1997) as
applying only to those regulatory actions that concern health or safety
risks, such that the analysis required under section 5-501 of the EO
has the potential to influence the regulation. This action is not
subject to EO 13045 because it does not establish an environmental
standard intended to mitigate health or safety risks.

H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use

    This action is not subject to Executive Order 13211 (66 FR 28355
(May 22, 2001)), because it is not a significant regulatory action
under Executive Order 12866.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (``NTTAA''), Public Law 104-113 (15 U.S.C. 272 note),
directs the EPA to use voluntary consensus standards in its regulatory
activities unless to do so would be inconsistent with applicable law or
otherwise impractical. Voluntary consensus standards are technical
standards (e.g., materials specifications, test methods, sampling
procedures, and business practices) that are developed or adopted by
voluntary consensus standards bodies. NTTAA directs the EPA to provide
Congress, through OMB, explanations when the agency decides not to use
available and applicable voluntary consensus standards.
    This rule involves environmental monitoring and measurement
consistent with the agency's Performance Based Measurement System
(PBMS). The PBMS approach is intended to be more flexible and cost-
effective for the regulated community; it is also intended to encourage
innovation in analytical technology and improved data quality.
Specifically, this rule establishes a new FRM for Pb in TSP
measurements. The EPA used voluntary consensus standards in the
preparation of this FRM. The FRM is the benchmark against which all
ambient monitoring methods are compared. The FRM is not a voluntary
consensus standard.
    The FEM equivalency criteria contained in 40 CFR part 53 constitute
performance criteria. Therefore, the EPA is not precluding the use of
any method, whether it constitutes a voluntary consensus standard or
not, as long as it meets the specified performance criteria in 40 CFR
part 53 and is approved by the EPA pursuant to those regulations.

J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

    Executive Order (EO) 12898 (59 FR 7629 (Feb. 16, 1994)) establishes
federal executive policy on environmental justice. Its main provision
directs federal agencies, to the greatest extent practicable and
permitted by law, to make environmental justice part of their mission
by identifying and addressing, as appropriate, disproportionately high
and adverse human health or environmental effects of their programs,
policies, and activities on minority populations and low-income
populations in the United States.
    The EPA has determined that this rule will not have
disproportionately high and adverse human health or environmental
effects on minority or low-income populations because it does not
affect the level of protection provided to human health or the
environment. This action establishes a new FRM for state and local air
monitoring agencies to use as one of the approved methods for
measurement of Pb in TSP and designates the existing FRM as an FEM.

K. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. The EPA will submit a report containing this rule and
other required information to the U.S. Senate, the U.S. House of
Representatives, and the Comptroller General of the United States prior
to publication of the rule in the Federal Register. A major rule cannot
take effect until 60 days after it is published in the Federal
Register. This action is not a ``major rule'' as defined by 5 U.S.C.
804(2). This rule will be effective August 2, 2013.

List of Subjects in 40 CFR Part 50

    Environmental protection, Air pollution control, and Lead.

    Dated: June 26, 2013.
Bob Perciasepe,
Acting Administrator.

    For reasons stated in the preamble, title 40, chapter I of the Code
of Federal Regulations sets forth the following.

PART 50--NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY
STANDARDS

0
1. The authority citation for part 50 continues to read as follows:

    Authority: 42 U.S.C. 7401, et seq.

0
2. Appendix G to part 50 is revised to read as follows:

Appendix G to Part 50--Reference Method for the Determination of Lead
in Total Suspended Particulate Matter

1.0 Scope and Applicability

    Based on review of the air quality criteria and national ambient
air quality standard (NAAQS) for lead (Pb) completed in 2008, the
EPA made revisions to the primary and secondary NAAQS for Pb to
protect public health and welfare. The EPA revised the level from
1.5 [mu]g/m\3\ to 0.15 [mu]g/m\3\ while retaining the current
indicator of Pb in total suspended particulate matter (Pb-TSP).
    Pb-TSP is collected for 24 hours on a TSP filter as described in
Appendix B of part 50, the Reference Method for the Determination of
Suspended Particulate Matter in the Atmosphere (High-Volume Method).
This method is for the analysis of Pb from TSP filters by
Inductively Coupled Plasma Mass Spectrometry (ICP-MS) using a heated
ultrasonic bath with nitric acid (HNO3) and hydrochloric
acid (HCl) or a heated block (hot block) digester with
HNO3 for filter extraction.
    This method is based on the EPA's Office of Solid Waste (SW-846)
Method 6020A--Inductively Coupled Plasma Mass Spectrometry (U.S.
EPA, 2007). Wording in certain sections of this method is
paraphrased or taken directly from Method 6020A.
    1.1 ICP-MS is applicable for the sub-[micro]g/mL (ppb)
determination of Pb in a wide variety of matrices. Results reported
for monitoring or compliance purposes are calculated in [mu]g/m\3\
at local conditions (LC). This procedure describes a method for the
acid extraction of Pb in particulate matter collected on glass
fiber, quartz, or PTFE filters and measurement of the extracted Pb
using ICP-MS.
    1.2 Due to variations in the isotopic abundance of Pb, the value
for total Pb must be based on the sum of the signal intensities for
isotopic masses, 206, 207, and 208. Most instrument software
packages are able to sum the primary isotope signal intensities
automatically.
    1.3 ICP-MS requires the use of an internal standard. \115\In
(Indium), \165\Ho (Holmium), and \209\Bi (Bismuth) are recommended
internal standards for the determination of Pb.
    1.4 Use of this method is restricted to use by, or under
supervision of, properly trained and experienced laboratory
personnel. Requirements include training and experience in inorganic
sample preparation, including acid extraction, and also knowledge in
the recognition and in the correction of spectral, chemical and
physical interference in ICP-MS.

2.0 Summary of Method

    2.1 This method describes the acid extraction of Pb in
particulate matter collected on glass fiber, quartz, or PTFE ambient
air filters with subsequent measurement of Pb by ICP-MS. Estimates
of the Method Detection Limit (MDL) or sensitivity of the method are
provided in Tables 1, 3 and 5 and determined using Pb-spiked filters
or filter strips analyzed in accordance with the guidance provided
in 40

CFR 136, Appendix B--Determination and procedures for the
Determination of the Method Detection Limit--Revision 1.1. The
analytical range of the method is 0.00024 [micro]g/m\3\ to 0.60
[micro]g/m\3\, and based on the low and high calibration curve
standards and a nominal filter sample volume of 2000 m\3\.
    2.2 This method includes two extraction methods. In the first
method, a solution of HNO3 and HCl is added to the
filters or filter strips in plastic digestion tubes and the tubes
are placed in a heated ultrasonic bath for one hour to facilitate
the extraction of Pb. Following ultrasonication, the samples are
brought to a final volume of 40 mL (50 mL for PTFE filters), vortex
mixed or shaken vigorously, and centrifuged prior to aliquots being
taken for ICP-MS analysis. In the second method, a solution of
dilute HNO3 is added to the filter strips in plastic
digestion tubes and the tubes placed into the hot block digester.
The filter strip is completely covered by the solution. The tubes
are covered with polypropylene watch glasses and refluxed. After
reflux, the samples are diluted to a final volume of 50 mL with
reagent water and mixed before analysis.
    2.3 Calibration standards and check standards are prepared to
matrix match the acid composition of the samples. ICP-MS analysis is
then performed. With this method, the samples are first aspirated
and the aerosol thus created is transported by a flow of argon gas
into the plasma torch. The ions produced (e.g., Pb\+1\) in the
plasma are extracted via a differentially-pumped vacuum interface
and are separated on the basis of their mass-to-charge ratio. The
ions are quantified by a channel electron multiplier or a Faraday
detector and the signal collected is processed by the instrument's
software. Interferences must be assessed and corrected for, if
present.

3.0 Definitions

Pb--Elemental or ionic lead
HNO3--Nitric acid
HCl--Hydrochloric acid
ICP-MS--Inductively Coupled Plasma Mass Spectrometer
MDL--Method detection limit
RSD--Relative standard deviation
RPD--Relative percent difference
CB--Calibration Blank
CAL--Calibration Standard
ICB--Initial calibration blank
CCB--Continuing calibration blank
ICV--Initial calibration verification
CCV--Continuing calibration verification
LLCV--Lower Level Calibration Verification, serves as the lower
level ICV and lower level CCV
RB--Reagent blank
RBS--Reagent blank spike
MSDS--Material Safety Data Sheet
NIST--National Institute of Standards and Technology
D.I. water--Deionized water
SRM--NIST Standard Reference Material
CRM--Certified Reference Material
EPA--Environmental Protection Agency
v/v--Volume to volume ratio

4.0 Interferences

    4.1 Reagents, glassware, plasticware, and other sample
processing hardware may yield artifacts and/or interferences to
sample analysis. If reagent blanks, filter blanks, or quality
control blanks yield results above the detection limit, the source
of contamination must be identified. All containers and reagents
used in the processing of the samples must be checked for
contamination prior to sample extraction and analysis. Reagents
shall be diluted to match the final concentration of the extracts
and analyzed for Pb. Labware shall be rinsed with dilute acid
solution and the solution analyzed. Once a reagent or labware
article (such as extraction tubes) from a manufacturer has been
successfully screened, additional screening is not required unless
contamination is suspected.
    4.2 Isobaric elemental interferences in ICP-MS are caused by
isotopes of different elements forming atomic ions with the same
nominal mass-to-charge ratio (m/z) as the species of interest. There
are no species found in ambient air that will result in isobaric
interference with the three Pb isotopes (206, 207, and 208) being
measured. Polyatomic interferences occur when two or more elements
combine to form an ion with the same mass-to-charge ratio as the
isotope being measured. Pb is not subject to interference from
common polyatomic ions and no correction is required.
    4.3 The distribution of Pb isotopes is not constant. The
analysis of total Pb should be based on the summation of signal
intensities for the isotopic masses 206, 207, and 208. In most
cases, the instrument software can perform the summation
automatically.
    4.4 Physical interferences are associated with the sample
nebulization and transport processes as well as with ion-
transmission efficiencies. Dissolved solids can deposit on the
nebulizer tip of a pneumatic nebulizer and on the interface skimmers
of the ICP-MS. Nebulization and transport processes can be affected
if a matrix component causes a change in surface tension or
viscosity. Changes in matrix composition can cause significant
signal suppression or enhancement. These interferences are
compensated for by use of internal standards. Sample dilution will
reduce the effects of high levels of dissolved salts, but
calibration standards must be prepared in the extraction medium and
diluted accordingly.
    4.5 Memory interferences are related to sample transport and
result when there is carryover from one sample to the next. Sample
carryover can result from sample deposition on the sample and
skimmer cones and from incomplete rinsing of the sample solution
from the plasma torch and the spray chamber between samples. These
memory effects are dependent upon both the analyte being measured
and sample matrix and can be minimized through the use of suitable
rinse times.

5.0 Health and Safety Cautions

    5.1 The toxicity or carcinogenicity of reagents used in this
method has not been fully established. Each chemical should be
regarded as a potential health hazard and exposure to these
compounds should be as low as reasonably achievable. Each laboratory
is responsible for maintaining a current file of OSHA regulations
regarding the safe handling of the chemicals specified in this
method. A reference file of material safety data sheets (MSDSs)
should be available to all personnel involved in the chemical
analysis. Specifically, concentrated HNO3 presents
various hazards and is moderately toxic and extremely irritating to
skin and mucus membranes. Use this reagent in a fume hood whenever
possible and if eye or skin contact occurs, flush with large volumes
of water. Always wear safety glasses or a shield for eye protection,
protective clothing, and observe proper mixing when working with
these reagents.
    5.2 Concentrated HNO3 and HCl are moderately toxic
and extremely irritating to the skin. Use these reagents in a fume
hood, and if eye and skin contact occurs, flush with large volumes
of water. Always wear safety glasses or a shield for eye protection
when working with these reagents. The component of this procedure
requiring the greatest care is HNO3. HNO3 is a
strong, corrosive, oxidizing agent that requires protection of the
eyes, skin, and clothing. Items to be worn during use of this
reagent include:
    1. Safety goggles (or safety glasses with side shields),
    2. Acid resistant rubber gloves, and
    3. A protective garment such as a laboratory apron.
HNO3 spilled on clothing will destroy the fabric; contact
with the skin underneath will result in a burn.
    It is also essential that an eye wash fountain or eye wash
bottle be available during performance of this method. An eye wash
bottle has a spout that covers the eye. If acid or any other
corrosive gets into the eye, the water in this bottle is squirted
onto the eye to wash out the harmful material. Eye washing should be
performed with large amounts of water immediately after exposure.
Medical help should be sought immediately after washing. If either
acid, but especially HNO3, is spilled onto the skin, wash
immediately with large amounts of water. Medical attention is not
required unless the burn appears to be significant. Even after
washing and drying, HNO3 may leave the skin slightly
brown in color; this will heal and fade with time.
    5.3 Pb salts and Pb solutions are toxic. Great care must be
taken to ensure that samples and standards are handled properly;
wash hands thoroughly after handling.
    5.4 Care must be taken when using the ultrasonic bath and hot
block digester as they are capable of causing mild burns. Users
should refer to the safety guidance provided by the manufacturer of
their specific equipment.
    5.5 Analytical plasma sources emit radio frequency radiation in
addition to intense ultra violet (UV) radiation. Suitable
precautions should be taken to protect personnel from such hazards.
The inductively coupled plasma should only be viewed with proper eye
protection from UV emissions.

6.0 Equipment

    6.1 Thermo Scientific X-Series ICP-MS or equivalent. The system
must be capable of providing resolution better or equal to 1.0
atomic mass unit (amu) at 10 percent peak height. The system must
have a mass range from at least 7 to 240 amu that allows for the
application of the internal standard technique. For the measurement
of Pb, an

instrument with a collision or reaction cell is not required.

6.2 Ultrasonic Extraction Equipment

    6.2.1 Heated ultrasonic bath capable of maintaining a
temperature of 80 [deg]C; VWR Model 750HT, 240W, or equivalent.
Ultrasonic bath must meet the following performance criteria:
    1. Cut a strip of aluminum foil almost the width of the tank and
double the depth.
    2. Turn the ultrasonic bath on and lower the foil into the bath
vertically until almost touching the bottom of the tank and hold for
10 seconds.
    3. Remove the foil from the tank and observe the distribution of
perforations and small pin prick holes. The indentations should be
fine and evenly distributed. The even distribution of indentations
indicates the ultrasonic bath is acceptable for use.
    6.2.2 Laboratory centrifuge, Beckman GS-6, or equivalent.
    6.2.3 Vortex mixer, VWR Signature Digital Vortex Mixer, VWR
Catalog No. 14005-824, or equivalent.
    6.3 Hot block extraction equipment
    6.3.1 Hot block digester, SCP Science DigiPrep Model MS, No.
010-500-205 block digester capable of maintaining a temperature of
95 [deg]C, or equivalent.
    6.4 Materials and Supplies
     Argon gas supply, 99.99 percent purity or better.
National Welders Microbulk, or equivalent.
     Plastic digestion tubes with threaded caps for
extraction and storage, SCP Science DigiTUBE[supreg] Item No. 010-
500-063, or equivalent.
     Disposable polypropylene ribbed watch glasses (for
heated block extraction), SCP Science Item No. 010-500-081, or
equivalent.
     Pipette, Rainin EDP2, 100 [mu]L,  1 percent
accuracy, <=1 percent RSD (precision), with disposable tips, or
equivalent.
     Pipette, Rainin EDP2, 1000 [mu]L,  1
percent accuracy, <=1 percent RSD (precision), with disposable tips,
or equivalent.
     Pipette, Rainin EDP2, 1-10 mL,  1 percent
accuracy, <=1 percent RSD (precision), with disposable tips, or
equivalent.
     Pipette, Thermo Lab Systems, 5 mL,  1
percent accuracy, <=1 percent RSD (precision), with disposable tips,
or equivalent.
     Plastic tweezer, VWR Catalog No. 89026-420, or
equivalent.
     Laboratory marker.
     Ceramic knife, Kyocera LK-25, and non-metal ruler or
other suitable cutting tools for making straight cuts for accurately
measured strips.
     Blank labels or labeling tape, VWR Catalog No. 36425-
045, or equivalent.
     Graduated cylinder, 1 L, VWR 89000-260, or equivalent.
     Volumetric flask, Class A, 1 L, VWR Catalog No. 89025-
778, or equivalent.
     Millipore Element deionized water system, or
equivalent, capable of generating water with a resistivity of >=17.9
M[Omega]-cm).
     Disposable syringes, 10-mL, with 0.45 micron filters
(must be Pb-free).
     Plastic or PTFE wash bottles.
     Glassware, Class A--volumetric flasks, pipettes, and
graduated cylinders.
     Glass fiber, quartz, or PTFE filters from the same
filter manufacturer and lot used for sample collection for use in
the determination of the MDL and for laboratory blanks.

7.0 Reagents and Standards

    7.1 Reagent--or trace metals-grade chemicals must be used in all
tests. Unless otherwise indicated, it is intended that all reagents
conform to the specifications of the Committee on Analytical
Reagents of the American Chemical Society, where such specifications
are available.
    7.2 Concentrated nitric acid, 67-70 percent, SCP Science Catalog
No. 250-037-177, or equivalent.
    7.3 Concentrated hydrochloric acid (for the ultrasonic
extraction method), 33-36 percent, SCP Science Catalog No. 250-037-
175, or equivalent.
    7.4 Deionized water--All references to deionized water in the
method refer to deionized water with a resistivity >=17.9 M[Omega]-
cm.
    7.5 Standard stock solutions may be commercially purchased for
each element or as a multi-element mix. Internal standards may be
purchased as a mixed multi-element solution. The manufacturer's
expiration date and storage conditions must be adhered to.
    7.5.1 Lead standard, 1000 [mu]g/mL, NIST traceable, commercially
available with certificate of analysis. High Purity Standards
Catalog No. 100028-1, or equivalent.
    7.5.2 Indium (In) standard, 1000 [mu]g/mL, NIST traceable,
commercially available with certificate of analysis. High Purity
Standards Catalog No. 100024-1, or equivalent.
    7.5.3 Bismuth (Bi) standard, 1000 [mu]g/mL, NIST traceable,
commercially available with certificate of analysis. High Purity
Standards Catalog No. 100006-1, or equivalent.
    7.5.4 Holmium (Ho) standard, 1000 [mu]g/mL, NIST traceable,
commercially available with certificate of analysis. High Purity
Standards Catalog No. 100023-1, or equivalent.
    7.5.5 Second source lead standard, 1000 [mu]g/mL, NIST
traceable, commercially available with certificate of analysis. Must
be from a different vendor or lot than the standard described in
7.5.1. Inorganic Ventures Catalog No. CGPB-1, or equivalent.
    7.5.6 Standard Reference Materials, NIST SRM 2583, 2586, 2587 or
1648, or equivalent.\5\
---------------------------------------------------------------------------

    \5\ Certificates of Analysis for these SRMs can be found at:
http://www.nist.gov/srm/index.cfm.
---------------------------------------------------------------------------

    Note: The In, Bi, and Ho internal standards may also be
purchased as 10 [micro]g/mL standards. Calibration standards are
prepared by diluting stock standards to the appropriate levels in
the same acid concentrations as in the final sample volume. The
typical range for calibration standards is 0.001 to 2.00 [micro]g/
mL. At a minimum, the curve must contain a blank and five Pb
containing calibration standards. The calibration standards are
stored at ambient laboratory temperature. Calibration standards must
be prepared weekly and verified against a freshly prepared ICV using
a NIST-traceable source different from the calibration standards.
    7.6 Internal standards may be added to the test solution or by
on-line addition. The nominal concentration for an internal standard
is 0.010 [micro]g/mL (10 ppb). Bismuth (Bi) or holmium (Ho) are the
preferred internal standards for Pb, but indium (In) may be used in
the event the sample contains Bi and high recoveries are observed.
    7.7 Three laboratory blank solutions are required for analysis:
(1) The calibration blank is used in the construction of the
calibration curve and as a periodic check of system cleanliness (ICB
and CCB); (2) the reagent blank (RB) is carried through the
extraction process to assess possible contamination; and (3) the
rinse blank is run between samples to clean the sample introduction
system. If RBs or laboratory blanks yield results above the
detection limit, the source of contamination must be identified.
Screening of labware and reagents is addressed in Section 4.1.
    7.7.1 The calibration blank is prepared in the same acid matrix
as the calibration standards and samples and contains all internal
standards used in the analysis.
    7.7.2 The RB contains all reagents used in the extraction and is
carried through the extraction procedure at the same time as the
samples.
    7.7.3 The rinse blank is a solution of 1 to 2 percent
HNO3 (v/v) in reagent grade water. A sufficient volume
should be prepared to flush the system between all standards and
samples analyzed.
    7.7.4 The EPA currently provides glass fiber, quartz, and PTFE
filters to air monitoring agencies as requested annually. As part of
the procurement process, these filters are tested for acceptance by
the EPA. The current acceptance criteria for glass fiber and quartz
filters is 15 [micro]g per filter or 0.0075 [micro]g/m\3\ using a
nominal sample volume of 2000 m\3\ and 4.8 ng/cm\2\ or 0.0024
[micro]g/m\3\ for PTFE filters using a nominal sample volume of 24
m\3\. Acceptance test results for filters obtained by the EPA are
typically well below the criterion specified and also below the
recently revised Pb method performance detection limit of 0.0075
[micro]g/m\3\; therefore, blank subtraction should not be performed.
    7.7.5 If filters are not provided by the EPA for sample
collection and analysis, filter lot blanks should be analyzed for Pb
content. For large filter lots (>500 filters), randomly select 20 to
30 filters from the lot and analyze the filter or filter strips for
Pb. For smaller filter lots, a lesser number of filters can be
analyzed. Glass, quartz and PTFE filters must not have levels of Pb
above the criteria specified in section 7.7.4 and, therefore, blank
correction should not be performed. If acceptance testing shows
levels of Pb above the criteria in Section 7.7.4, corrective action
must be taken to reduce the levels before proceeding.
    7.8 The Initial Calibration Verification (ICV), Lower Level
Calibration Verification (LLCV), and Continuing Calibration
Verification (CCV) solutions are prepared from a different Pb source
than the calibration curve standards and at a concentration that is
either at or below the midpoint on the calibration curve, but within
the calibration range. Both are prepared in the same acid matrix as
the calibration standards. Note that the same solution may be used
for both the ICV and CCV. The ICV/

CCV and LLCV solutions must be prepared fresh daily.
    7.9 Tuning Solution. Prepare a tuning solution according to the
instrument manufacturer's recommendations. This solution will be
used to verify the mass calibration and resolution of the
instrument.

8.0 Quality Control (QC)

    8.1 Standard QC practices shall be employed to assess the
validity of the data generated, including: MDL, RB, duplicate
samples, spiked samples, serial dilutions, ICV, CCV, LLCV, ICB, CCB,
and SRMs/CRMs.
    8.2 MDLs must be calculated in accordance with 40 CFR part 136,
Appendix B. RBs with low-level standard spikes are used to estimate
the MDL. The low-level standard spike is added to at least 7
individual filter strips and then carried through the entire
extraction procedure. This will result in at least 7 individual
samples to be used for the MDL. The recommended range for spiking
the strips is 1 to 5 times the estimated MDL.
    8.3 For each batch of samples, one RB and one reagent blank
spike (RBS) that is spiked at the same level as the sample spike
(see Section 8.6) must be prepared and carried throughout the entire
process. The results of the RB must be below 0.001 [micro]g/mL. The
recovery for the RBS must be within  20 percent of the
expected value. If the RB yields a result above 0.001 [micro]g/mL,
the source of contamination must be identified and the extraction
and analysis repeated. Reagents and labware must be suspected as
sources of contamination. Screening of reagents and labware is
addressed in Section 4.1.
    8.4 Any samples that exceed the highest calibration standard
must be diluted and rerun so that the concentration falls within the
curve. The minimum dilution will be 1 to 5 with matrix matched acid
solution.
    8.5 The internal standard response must be monitored during the
analysis. If the internal standard response falls below 70 percent
or rises above 120 percent of expected due to possible matrix
effects, the sample must be diluted and reanalyzed. The minimum
dilution will be 1 to 5 with matrix matched acid solution. If the
first dilution does not correct the problem, additional dilutions
must be run until the internal standard falls within the specified
range.
    8.6 For every batch of samples prepared, there must be one
duplicate and one spike sample prepared. The spike added is to be at
a level that falls within the calibration curve, normally the
midpoint of the curve. The initial plus duplicate sample must yield
a relative percent difference <= 20 percent. The spike must be
within  20 percent of the expected value.
    8.7 For each batch of samples, one extract must be diluted five-
fold and analyzed. The corrected dilution result must be within
10 percent of the undiluted result. The sample chosen
for the serial dilution shall have a concentration at or above 10X
the lowest standard in the curve to ensure the diluted value falls
within the curve. If the serial dilution fails, chemical or physical
interference should be suspected.
    8.8 ICB, ICV, LLCV, CCB and CCV samples are to be run as shown
in the following table.

------------------------------------------------------------------------
                                                        Performance
          Sample                  Frequency            specification
------------------------------------------------------------------------
ICB.......................  Prior to first sample  Less than 0.001 [mu]g/
                                                    mL.
ICV.......................  Prior to first sample  Within 90 to 110
                                                    percent of the
                                                    expected value.
LLCV......................  Daily, before first    10
                             sample and after       percent of the
                             last sample.           expected value.
CCB.......................  After every 10         Less than 0.001 [mu]g/
                             extracted samples.     mL.
CCV.......................  After every 10         Within 90-110 percent
                             extracted samples.     of the expected
                                                    value.
------------------------------------------------------------------------

    If any of these QC samples fails to meet specifications, the
source of the unacceptable performance must be determined, the
problem corrected, and any samples not bracketed by passing QC
samples must be reanalyzed.
    8.9 For each batch of samples, one certified reference material
(CRM) must be combined with a blank filter strip and carried through
the entire extraction procedure. The result must be within 10 percent of the expected value.
    8.10 For each run, a LLCV must be analyzed. The LLCV must be
prepared at a concentration not more than three times the lowest
calibration standard and at a concentration not used in the
calibration curve. The LLCV is used to assess performance at the low
end of the curve. If the LLCV fails (10 percent of the
expected value) the run must be terminated, the problem corrected,
the instrument recalibrated, and the analysis repeated.
    8.11 Pipettes used for volumetric transfer must have the
calibration checked at least once every 6 months and pass  1 percent accuracy and <= 1 percent RSD (precision) based on
five replicate readings. The pipettes must be checked weekly for
accuracy with a single replicate. Any pipette that does not meet
 1 percent accuracy on the weekly check must be removed
from service, repaired, and pass a full calibration check before
use.
    8.12 Samples with physical deformities are not quantitatively
analyzable. The analyst should visually check filters prior to
proceeding with preparation for holes, tears, or non-uniform deposit
which would prevent representative sampling. Document any
deformities and qualify the data with flags appropriately. Care must
be taken to protect filters from contamination. Filters must be kept
covered prior to sample preparation.
    9.0 ICP MS Calibration
    Follow the instrument manufacturer's instructions for the
routine maintenance, cleaning, and ignition procedures for the
specific ICP-MS instrument being used.
    9.1 Ignite the plasma and wait for at least one half hour for
the instrument to warm up before beginning any pre-analysis steps.
    9.2 For the Thermo X-Series with Xt cones, aspirate a 10 ng/mL
tuning solution containing In, Bi, and Ce (Cerium). Monitor the
intensities of In, Bi, Ce, and CeO (Cerium oxide) and adjust the
instrument settings to achieve the highest In and Bi counts while
minimizing the CeO/Ce oxide ratio. For other instruments, follow the
manufacturer's recommended practice. Tune to meet the instrument
manufacturer's specifications. After tuning, place the sample
aspiration probe into a 2 percent HNO3 rinse solution for
at least 5 minutes to flush the system.
    9.3 Aspirate a 5 ng/mL solution containing Co, In, and Bi to
perform a daily instrument stability check. Run 10 replicates of the
solution. The percent RSD for the replicates must be less than 3
percent at all masses. If the percent RSD is greater than 3 percent,
the sample introduction system, pump tubing, and tune should be
examined, and the analysis repeated. Place the sample aspiration
probe into a 2 percent HNO3 rinse solution for at least 5
minutes to flush the system.
    9.4 Load the calibration standards in the autosampler and
analyze using the same method parameters that will be used to
analyze samples. The curve must include one blank and at least 5 Pb-
containing calibration standards. The correlation coefficient must
be at least 0.998 for the curve to be accepted. The lowest standard
must recover  15 percent of the expected value and the
remaining standards must recover  10 percent of the
expected value to be accepted.
    9.5 Immediately after the calibration curve is completed,
analyze an ICV and an ICB. The ICV must be prepared from a different
source of Pb than the calibration standards. The ICV must recover
90-110 percent of the expected value for the run to continue. The
ICB must be less than 0.001 [micro]g/mL. If either the ICV or the
ICB fails, the run must be terminated, the problem identified and
corrected, and the analysis re-started.
    9.6 A LLCV, CCV and a CCB must be run after the ICV and ICB. A
CCV and CCB must be run at a frequency of not less than every 10
extracted samples. A typical analytical run sequence would be:
Calibration blank, Calibration standards, ICV, ICB, LLCV, CCV, CCB,
Extracts 1-10, CCV, CCB, Extracts 11-20, CCV, CCB, Extracts 21-30,
CCV, CCB, LLCV, CCV, CCB. Extracts are any field sample or QC
samples that have been carried through the extraction process. The
CCV solution is prepared from a different source than the
calibration standards and may be the same as the ICV solution. The
LLCV must be within  10 percent of expected value. The
CCV value must be within  10 percent of expected for the
run to continue. The CCB must be less than 0.001 [mu]g/mL. If either
the CCV, LLCV, or CCB fails, the run must be terminated, the problem
identified and

corrected, and the analysis re-started from the last passing CCV/
LLCV/CCB set.
    9.7 A LLCV, CCV, and CCB set must be run at the end of the
analysis. The LLCV must be within  30 percent of
expected value. If either the CCV, LLCV, or CCB fails, the run must
be terminated, the problem identified and corrected, and the
analysis re-started from the last passing CCV/LLCV/CCB set.

10.0 Heated Ultrasonic Filter Strip Extraction

    All plasticware (e.g., Nalgene) and glassware used in the
extraction procedures is soaked in 1 percent HNO3 (v/v)
for at least 24 hours and rinsed with reagent water prior to use.
All mechanical pipettes used must be calibrated to 1
percent accuracy and <= 1 percent RSD at a minimum of once every 6
months.
    10.1 Sample Preparation--Heated Ultrasonic Bath
    10.1.1 Extraction solution (1.03M HNO3 + 2.23M HCl).
Prepare by adding 500 mL of deionized water to a 1000 mL flask,
adding 64.4 mL of concentrated HNO3 and 182 mL of
concentrated HCl, shaking to mix, allowing solution to cool,
diluting to volume with reagent water, and inverting several times
to mix. Extraction solution must be prepared at least weekly.
    10.1.2 Use a ceramic knife and non-metal ruler, or other cutting
device that will not contaminate the filter with Pb. Cut a \3/4\
inch X 8 inch strip from the glass fiber or quartz filter by cutting
a strip from the edge of the filter where it has been folded along
the 10 inch side at least 1 inch from the right or left side to
avoid the un-sampled area covered by the filter holder. The filters
must be carefully handled to avoid dislodging deposits.
    10.1.3 Using plastic tweezers, roll the filter strip up in a
coil and place the rolled strip in the bottom of a labeled 50 mL
extraction tube. In a fume hood, add 15.00  0.15 mL of
the extraction solution (see Section 10.1.1) using a calibrated
mechanical pipette. Ensure that the extraction solution completely
covers the filter strip.
    10.1.4 Loosely cap the 50 mL extraction tube and place it
upright in a plastic rack. When all samples have been prepared,
place the racks in an uncovered heated ultrasonic water bath that
has been preheated to 80  5[deg]C and ensure that the
water level in the ultrasonic is above the level of the extraction
solution in the tubes but well below the level of the extraction
tube caps to avoid contamination. Start the ultrasonic bath and
allow the unit to run for 1 hour  5 minutes at 80  5[deg]C.
    10.1.5 Remove the rack(s) from the ultrasonic bath and allow the
racks to cool.
    10.1.6 Add 25.00  0.25 mL of D.I. water with a
calibrated mechanical pipette to bring the sample to a final volume
of 40.0  0.4 mL. Tightly cap the tubes, and vortex mix
or shake vigorously. Place the extraction tubes in an appropriate
holder and centrifuge for 20 minutes at 2500 revolutions per minute
(RPM).
    CAUTION--Make sure that the centrifuge holder has a flat bottom
to support the flat bottomed extraction tubes.
    10.1.7 Pour an aliquot of the solution into an autosampler vial
for ICP-MS analysis to avoid the potential for contamination. Do not
pipette an aliquot of solution into the autosampler vial.
    10.1.8 Decant the extract to a clean tube, cap tightly, and
store the sample extract at ambient laboratory temperature. Extracts
may be stored for up to 6 months from the date of extraction.
    10.2 47 mm PTFE Filter Extraction--Heated Ultrasonic Bath
    10.2.1 Extraction solution (1.03M HNO3 + 2.23M HCl).
Prepare by adding 500 mL of D.I. water to a 1000mL flask, adding
64.4 mL of concentrated HNO3 and 182 mL of concentrated
HCl, shaking to mix, allowing solution to cool, diluting to volume
with reagent water, and inverting several times to mix. Extraction
solution must be prepared at least weekly.
    10.2.2 Using plastic tweezers, bend the PTFE filter into a U-
shape and insert the filter into a labeled 50 mL extraction tube
with the particle loaded side facing the center of the tube. Gently
push the filter to the bottom of the extraction tube. In a fume
hood, add 25.00  0.15 mL of the extraction solution (see
Section 10.2.1) using a calibrated mechanical pipette. Ensure that
the extraction solution completely covers the filter.
    10.2.3 Loosely cap the 50 mL extraction tube and place it
upright in a plastic rack. When all samples have been prepared,
place the racks in an uncovered heated ultrasonic water bath that
has been preheated to 80  5[deg]C and ensure that the
water level in the ultrasonic is above the level of the extraction
solution in the tubes, but well below the level of the extraction
tube caps to avoid contamination. Start the ultrasonic bath and
allow the unit to run for 1 hour  5 minutes at 80  5[deg]C.
    10.2.4 Remove the rack(s) from the ultrasonic bath and allow the
racks to cool.
    10.2.5 Add 25.00  0.25 mL of D.I. water with a
calibrated mechanical pipette to bring the sample to a final volume
of 50.0  0.4 mL. Tightly cap the tubes, and vortex mix
or shake vigorously. Allow samples to stand for one hour to allow
complete diffusion of the extracted Pb. The sample is now ready for
analysis.
    Note: Although PTFE filters have only been extracted using the
ultrasonic extraction procedure in the development of this FRM, PTFE
filters are inert and have very low Pb content. No issues are
expected with the extraction of PTFE filters using the heated block
digestion method. However, prior to using PTFE filters in the heated
block extraction method, extraction method performance test using
CRMs must be done to confirm performance (see Section 8.9).

11.0 Hot Block Filter Strip Extraction

    All plasticware (e.g., Nalgene) and glassware used in the
extraction procedures is soaked in 1 percent HNO3 for at
least 24 hours and rinsed with reagent water prior to use. All
mechanical pipettes used must be calibrated to 1 percent
accuracy and <= 1 percent RSD at a minimum of once every 6 months.
    11.1 Sample Preparation--Hot Block Digestion
    11.1.1 Extraction solution (1:19, v/v HNO3). Prepare
by adding 500 mL of D.I. water to a 1000 mL flask, adding 50 mL of
concentrated HNO3, shaking to mix, allowing solution to
cool, diluting to volume with reagent water, and inverting several
times to mix. The extraction solution must be prepared at least
weekly.
    11.1.2 Use a ceramic knife and non-metal ruler, or other cutting
device that will not contaminate the filter with Pb. Cut a 1-inch X
8-inch strip from the glass fiber or quartz filter. Cut a strip from
the edge of the filter where it has been folded along the 10-inch
side at least 1 inch from the right or left side to avoid the un-
sampled area covered by the filter holder. The filters must be
carefully handled to avoid dislodging particle deposits.
    11.1.3 Using plastic tweezers, roll the filter strip up in a
coil and place the rolled strip in the bottom of a labeled 50 mL
extraction tube. In a fume hood, add 20.0  0.15 mL of
the extraction solution (see Section 11.1.1) using a calibrated
mechanical pipette. Ensure that the extraction solution completely
covers the filter strip.
    11.1.4 Place the extraction tube in the heated block digester
and cover with a disposable polyethylene ribbed watch glass. Heat at
95  5[deg]C for 1 hour and ensure that the sample does
not evaporate to dryness. For proper heating, adjust the temperature
control of the hot block such that an uncovered vessel containing 50
mL of water placed in the center of the hot block can be maintained
at a temperature approximately, but no higher than 85[ordm]C. Once
the vessel is covered with a ribbed watch glass, the temperature of
the water will increase to approximately 95[deg]C.
    11.1.5 Remove the rack(s) from the heated block digester and
allow the samples to cool.
    11.1.6 Bring the samples to a final volume of 50 mL with D.I.
water. Tightly cap the tubes, and vortex mix or shake vigorously for
at least 5 seconds. Set aside (with the filter strip in the tube)
for at least 30 minutes to allow the HNO3 trapped in the
filter to diffuse into the extraction solution.
    11.1.7 Shake thoroughly (with the filter strip in the digestion
tube) and let settle for at least one hour. The sample is now ready
for analysis.

12.0 Measurement Procedure

    12.1 Follow the instrument manufacturer's startup procedures for
the ICP-MS.
    12.2 Set instrument parameters to the appropriate operating
conditions as presented in the instrument manufacturer's operating
manual and allow the instrument to warm up for at least 30 minutes.
    12.3 Calibrate the instrument per Section 9.0 of this method.
    12.4 Verify the instrument is suitable for analysis as defined
in Sections 9.2 and 9.3.
    12.5 As directed in Section 8.0 of this method, analyze an ICV
and ICB immediately after the calibration curve followed by a LLCV,
then CCV and CCB. The acceptance requirements for these parameters
are presented in Section 8.8.
    12.6 Analyze a CCV and a CCB after every 10 extracted samples.
    12.7 Analyze a LLCV, CCV and CCB at the end of the analysis.

    12.8 A typical sample run will include field samples, field
sample duplicates, spiked field sample extracts, serially diluted
samples, the set of QC samples listed in Section 8.8 above, and one
or more CRMs or SRMs.
    12.9 Any samples that exceed the highest standard in the
calibration curve must be diluted and reanalyzed so that the diluted
concentration falls within the calibration curve.
    13.0 Results
    13.1 The filter results must be initially reported in [mu]g/mL
as analyzed. Any additional dilutions must be accounted for. The
internal standard recoveries must be included in the result
calculation; this is done by the ICP-MS software for most
commercially-available instruments. Final results should be reported
in [mu]g Pb/m\3\ to three significant figures as follows:

C = (([mu]g Pb/mL * Vf * A)* D))/Vs

Where:
C = Concentration, [mu]g Pb/m\3\
[mu]g Pb/mL = Lead concentration in solution
Vf = Total extraction solution volume
A = Area correction; \3/4\'' x 8'' strip = 5.25 in\2\ analyzed, A =
12.0 or 1'' x 8'' strip = 7 in\2\ analyzed, A = 9.0
D = dilution factor (if required)
Vs = Actual volume of air sampled

    The calculation assumes the use of a standard 8-inch x 10-inch
TSP filter which has a sampled area of 9-inch x 7-inch (63.0 in\2\)
due to the \1/2\-inch filter holder border around the outer edge.
The \3/4\-inch x 8-inch strip has a sampled area of \3/4\-inch x 7-
inch (5.25 in\2\). The 1-inch x 8-inch strip has a sampled area of
1-inch x 7-inch (7.0 in\2\). If filter lot blanks are provided for
analysis, refer to Section 7.7.5 of this method for guidance on
testing.

14.0 Method Performance

    Information in this section is an example of typical performance
results achieved by this method. Actual performance must be
demonstrated by each individual laboratory and instrument.
    14.1 Performance data have been collected to estimate MDLs for
this method. MDLs were determined in accordance with 40 CFR 136,
Appendix B. MDLs were estimated for glass fiber, quartz, and PTFE
filters using seven reagent/filter blank solutions spiked with low
level Pb at three times the estimated MDL of 0.001 [mu]g/mL. Tables
1, 3, and 5 shows the MDLs estimated using both the ultrasonic and
hot block extraction methods for glass fiber and quartz filters and
the ultrasonic method for PTFE filters. The MDLs are well below the
EPA requirement of five percent of the current Pb NAAQS or 0.0075
[mu]g/m\3\. These MDLs are provided to demonstrate the adequacy of
the method's performance for Pb in TSP. Each laboratory using this
method should determine MDLs in their laboratory and verify them
annually. It is recommended that laboratories also perform the
optional iterative procedure in 40 CFR 136, Appendix B to verify the
reasonableness of the estimated MDL and subsequent MDL
determinations.
    14.2 Extraction method recovery tests with glass fiber and
quartz filter strips, and PTFE filters spiked with NIST SRMs were
performed using the ultrasonic/HNO3 and HCl filter
extraction methods and measurement of the dissolved Pb with ICP-MS.
Tables 2, 4, and 6 show recoveries obtained with these SRM. The
recoveries for all SRMs were >=90 percent at the 95 percent
confidence level.

Table 1--Method Detection Limits Determined by Analysis of Reagent/Glass
          Fiber Filter Blanks Spiked With Low-level Pb Solution
------------------------------------------------------------------------
                                                 Ultrasonic    Hotblock
                                                 extraction   extraction
                                                   method       method
                                               -------------------------
                                                [mu]g/m\3\*  [mu]g/m\3\*
------------------------------------------------------------------------
n = 1.........................................    0.0000702     0.000533
n = 2.........................................    0.0000715     0.000482
n = 3.........................................    0.0000611     0.000509
n = 4.........................................    0.0000587     0.000427
n = 5.........................................    0.0000608     0.000449
n = 6.........................................    0.0000607     0.000539
n = 7.........................................    0.0000616     0.000481
Average.......................................    0.0000635     0.000489
Standard Deviation............................    0.0000051     0.000042
MDL**.........................................    0.0000161     0.000131
------------------------------------------------------------------------
* Assumes 2000 m\3\ of air sampled.
** MDL is 3.143 times the standard deviation of the results for seven
  sample replicates analyzed.

                   Table 2--Recoveries of Lead From NIST SRMs Spiked Onto Glass Fiber Filters
----------------------------------------------------------------------------------------------------------------
                                                                    Recovery, ICP-MS, (percent)
                                                 ---------------------------------------------------------------
                Extraction method                    NIST 1547                                       NIST 2582
                                                       plant      NIST 2709 soil  NIST 2583 dust       paint
----------------------------------------------------------------------------------------------------------------
Ultrasonic Bath.................................      100  4        minus> 1        minus> 8        minus> 0
Block Digestion.................................       92  7        minus> 3        minus> 4        minus> 4
----------------------------------------------------------------------------------------------------------------

   Table 3--Method Detection Limits Determined by Analysis of Reagent/
         Quartz Filter Blanks Spiked With Low-level Pb Solution
------------------------------------------------------------------------
                                                 Ultrasonic    Hotblock
                                                 extraction   extraction
                                                   method       method
                                               -------------------------
                                                [mu]g/m\3\*  [mu]g/m\3\*
------------------------------------------------------------------------
n = 1.........................................     0.000533     0.000274
n = 2.........................................     0.000552     0.000271
n = 3.........................................     0.000534     0.000281
n = 4.........................................     0.000684     0.000269

n = 5.........................................     0.000532     0.000278
n = 6.........................................     0.000532     0.000272
n = 7.........................................     0.000552     0.000261
Average.......................................     0.000560     0.000272
Standard Deviation............................     0.000055     0.000007
MDL**.........................................     0.000174     0.000021
------------------------------------------------------------------------
* Assumes 2000 m\3\ of air sampled.
** MDL is 3.143 times the standard deviation of the results for seven
  sample replicates analyzed.

                   Table 4--Recoveries of Lead From NIST SRMs Spiked Onto Quartz Fiber Filters
----------------------------------------------------------------------------------------------------------------
                                                                    Recovery, ICP-MS, (percent)
                                                 ---------------------------------------------------------------
                Extraction method                    NIST 1547                                       NIST 2582
                                                       plant      NIST 2709 soil  NIST 2583 dust       paint
----------------------------------------------------------------------------------------------------------------
Ultrasonic Bath.................................      101  6        minus> 1        minus> 5        minus> 1
Block Digestion.................................      106  3        minus> 3        minus> 6        minus> 2
----------------------------------------------------------------------------------------------------------------

 Table 5--Method Detection Limits Determined by Analysis of Reagent/PTFE
             Filter Blanks Spiked With Low-Level Pb Solution
------------------------------------------------------------------------
                                                            Ultrasonic
                                                            extraction
                                                              method
                                                         ---------------
                                                            [mu]g/m\3\*
------------------------------------------------------------------------
n = 1...................................................        0.001775
n = 2...................................................        0.001812
n = 3...................................................        0.001773
n = 4...................................................        0.001792
n = 5...................................................        0.001712
n = 6...................................................        0.001767
n = 7...................................................        0.001778
Average.................................................        0.001773
Standard Deviation......................................        0.000031
MDL**...................................................        0.000097
------------------------------------------------------------------------
* Assumes 24 m\3\ of air sampled.
** MDL is 3.143 times the standard deviation of the results for seven
  sample replicates analyzed.

                       Table 6--Recoveries of Lead From NIST SRMs Spiked Onto PTFE Filters
----------------------------------------------------------------------------------------------------------------
                                                                    Recovery, ICP-MS, (percent)
                                                 ---------------------------------------------------------------
                Extraction method                    NIST 1547                                       NIST 2582
                                                       plant      NIST 2709 soil  NIST 2583 dust       paint
----------------------------------------------------------------------------------------------------------------
Ultrasonic Bath.................................      104  5        minus> 1       minus> 11        minus> 3
----------------------------------------------------------------------------------------------------------------

15.0 Pollution Prevention

    15.1 Pollution prevention encompasses any technique that reduces
or eliminates the quantity and/or toxicity of waste at the point of
generation. Numerous opportunities for pollution prevention exist in
laboratory operations. Whenever feasible, laboratory personnel
should use pollution prevention techniques to address their waste
generation. The sources of pollution generated with this procedure
are waste acid extracts and Pb-containing solutions.
    15.2 For information about pollution prevention that may be
applicable to laboratories and research institutions, consult Less
is Better: Laboratory Chemical Management for Waste Reduction,
available from the American Chemical Society's Department of
Government Relations and Science Policy, 1155 16th St. NW.,
Washington, DC 20036, www.acs.org.

16.0 Waste Management

    16.1 Laboratory waste management practices must be conducted
consistent with all applicable rules and regulations. Laboratories
are urged to protect air, water, and land by minimizing all releases
from hood and bench operations, complying with the letter and spirit
of any sewer and discharge permits and regulations, and by complying
with all solid and hazardous waste regulation. For further
information on waste management, consult The Waste Management Manual
for Laboratory Personnel available from the American Chemical
Society listed in Section 15.2 of this method.

    16.2 Waste HNO3, HCl, and solutions containing these
reagents and/or Pb must be placed in labeled bottles and delivered
to a commercial firm that specializes in removal of hazardous waste.

17.0 References

FACDQ (2007). Report of the Federal Advisory Committee on Detection
and Quantitation Approaches and Uses in Clean Water Act Programs,
submitted to the U.S. EPA December 2007. Available: http://water.epa.gov/scitech/methods/cwa/det/upload/final-report-200712.pdf.
Rice J (2013). Results from the Development of a New Federal
Reference Method (FRM) for Lead in Total Suspended Particulate (TSP)
Matter. Docket  EPA-HQ-OAR-2012-0210.
U.S. EPA (2007). Method 6020A--Inductively Coupled Plasma Mass
Spectrometry. U.S. Environmental Protection Agency. Revision 1,
February 2007. Available: http://www.epa.gov/osw/hazard/testmethods/sw846/pdfs/6020a.pdf.
U.S. EPA (2011). A Laboratory Study of Procedures Evaluated by the
Federal Advisory Committee on Detection and Quantitation Approaches
and Uses in Clean Water Act Programs. December 2011. Available:
http://water.epa.gov/scitech/methods/cwa/det/upload/fac_report_2009.pdf.
[FR Doc. 2013-15880 Filed 7-2-13; 8:45 am]
BILLING CODE 6560-50-P