Development of an analytical method for per- and polyfluoroalkyl substances (PFAS) using high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS)

Status:

completed 12/2024

Aims:

Per- and polyfluoroalkyl substances (PFASs) are aliphatic organic compounds used in numerous industries and products owing to their ability to repel water, dirt and grease. The substances and their degradation products possess high chemical and thermal stability and are very persistent in the environment. The EU is continually expanding its bans of PFASs and the regulations governing them, and further potentially carcinogenic PFASs are continually being added to the SVHC list, the list of substances of very high concern. The MAK Commission has already laid down an assessment criterion for workplace air for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS).

To enable workplace exposure to PFASs to be checked in the future, an analysis method employing high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) was to be developed for 14 PFASs. A major challenge presented by this method is the avoidance of contamination during the analytic processes. PFASs are now ubiquitous and are found in solvents, analytical equipment and consumables. A special procedure was therefore required for the entire laboratory process and the analysis method. The US Environmental Protection Agency’s "EPA Method 533" was to serve as the basis for development of the method.

Activities/Methods:

The first step involved adaptation of the HPLC system, in order to reduce PFAS blank values from the analysis system to a minimum. This entailed replacing all hoses, filters, seals and connectors with PFAS-free components. In the second step, an HPLC-MS/MS method was developed for analysis of the following analytes: PFBA, PFPeA, PFBS, PFHxA, PFHpA, PFHxS, PFOA, PFNA, PFOS, PFDA, PFUnDA, PFDoA, PFTeDA and PFTrDA. The performance of the analytical method was then tested to determine its sensitivity and selectivity. Finally, process parameters specific to the equipment were determined, such as the measuring range and the linearity of the calibration.

Results:

Conversion of the HPLC system and adjustment of the equipment parameters enabled an analysis method without blank values to be developed for determining 14 PFAS by the use of LC-MS/MS. A linear measuring range of 0.5 µg/L to 15 µg/L was determined for the substances PFBA, PFPeA, PFBS, PFHxA, PFHpA, PFHxS, PFOA, PFNA, PFOS, PFDA, PFUnDA and PFDoA. For PFTeDA and PFTrDA, the measuring range extends from 2.5 µg/L to 15 µg/L. The method developed thus satisfies the criteria for analysis of up to 1/10 of the assessment criteria for the compounds PFOA and PFOS.

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