Derivatization Methods for Perfluoroalkyl Substances (PFAS) by Gas Chromatography/Tandem Mass Spectrometry (GC-MS/MS)

Description:
The perfluoroalkyl substances (PFAS) are environmentally persistent, non-degradable, bioaccumulative, and potentially harmful. These “forever chemicals” are widely distributed across the globe, and methods are needed for the rapid and routine analysis in a variety of matrices. Gas chromatography with mass spectrometry (GC/MS) is commonly used for the analysis of water samples, but PFAS compounds pose special problems in sample pretreatment, separation, and detection. Here, we present our work towards a sensitive, simple, and reliable analytical technique for the determination of perfluorocarboxylic acids (PFCAs) by GC-MS/MS. We compare the performance of two derivatization methods – esterification with isobutyl chloroformate (IBCF) and amidation with 2,4-difluoroaniline (DFA) - and report optimized conditions for the derivatization reactions, as well as their GC retention properties and characteristic mass spectrometric fragments. The overall instrument detection limit is determined from a calibration curve study, and found to be acceptable for the analysis of surface water samples following appropriate enrichment by solid-phase extraction (SPE) and derivatization.