Per- and polyfluoroalkyl substances (PFAS) are a group of persistent organic pollutants, widely found in the environment. To protect people from exposure to these pollutants international, national, and regional agencies such as the United States Environmental Protection Agency (US EPA) and the International Organization for Standardization (ISO) provide methods for trace-level analysis of these compounds. For example, US EPA methods 533 and 537.1, as well as ISO method 21675 can be used for the analysis of drinking water with liquid chromatography/tandem mass spectrometry (LC/MS/MS).
High-performance liquid chromatography (HPLC) instruments in their standard configuration contain per- and polyfluorinated compounds (PFCs), including fluoropolymers such as PTFE, PFA, etc. These materials are used because of their chemical inertness, ensuring the compatibility of the LC instruments with a broad range of acids, bases, and organic solvents. However, during the production of PFC, per- and polyfluorinated alkyl substances (PFASs), such as perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), or replacement chemicals with similar properties are used as processing agents. Traces of these PFAS processing agents can remain in fluoropolymers. When running PFAS analysis at the ppb level and below, using LC/MS/MS instruments, the PFAS leaching from the LC instrument during operation can cause an increased background. This increased background can have a severe impact on meeting the required quantification and detection limits set by regional and national regulations. Therefore, it is up to the user to take the necessary steps to minimize the impact of the LC/MS system on the analytical results. Two recommendations from the US EPA are (1) to replace standard solvent lines with alternative ones made of PEEK and (2) to use a delay column, which can help to further reduce the background, especially if it is caused by the mobile phase. Download now to learn more.