From measuring result to concentration - the creation of a custom function

Most manufacturers of liquid products convert the measurement result such as density, sound velocity or refractive index into a more commonly used unit. A custom function – or user function – makes the conversion possible.

Why create a custom function?

Variables to characterize a binary or ternary liquid sample are for example density, sound velocity or refractive index - but what do the results actually mean? These results can be converted into “imaginable” units such as °Brix, percent or similar - an answer that most analysts prefer to the results as determined directly by the instrument. Many modern instruments are already equipped with numerous common conversion tables, but for more specific samples an individual conversion formula needs to be developed.

A measurement result obtained by the meter can be expressed in terms of a concentration unit either by means of a table which is already incorporated into the software or, if no such table is available, by means of a custom (or user) function. User functions can be implemented into numerous Anton Paar meters such as DMA 35, Snap 51, DMA M, DSA M, SDA M and PBA measuring systems as well as into Anton Paar's range of online process systems (e.g. with the evaluation unit mPDS 5 or the transmitter Pico 3000). For process applications, the temperature must always be considered as an input value for the conversion formulae.

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