Current LC/MS Approaches for PFAS Analysis with Ultrashort and Long Chain Mixtures

Per- and polyfluoroalkyl substances (PFAS) are a group of chemicals used to make fluoropolymer coatings and other products that resist heat, oil, stains, grease, and water. These toxic “forever chemicals” have led to significant public health and environmental concerns and increased need for diligence in surveillance, production, storage and mitigation.

Current Environmental Protection Agency (EPA) methods will be demonstrated using superficially porous particle technology columns including EPA 533, 537.1, 8327, and 1633. Recently, methods involving significantly larger injection volumes and elimination of solid phase extraction sample preparation have been evaluated in order to speed up analysis times and throughput.

There has been a growing concern over the ultrashort chain PFAS chemicals, including trifluoracetic acid (TFA) and PFPrA, which can be challenging to analyze due to low retention and sensitivity via reversed phase LC/MS/MS. Although mixed mode hydrophilic interaction liquid chromatography (HILIC) has been demonstrated to improve retention, this approach has limitations. A new reversed phase, superficially porous particle (SPP) silica with a positive charge surface chemistry and hydrophobic silane modifier (HALO® PCS) has shown to have advantages to improve short chain PFAS while allowing adequate resolution of the mid- and long-chain analytes.