Interactions of per- and polyfluoroalkyl substances with polypropylene plastic and borosilicate glass: Resolving key uncertainties for accurate analysis

Abstract

This study addresses critical uncertainties regarding the interactions of per- and polyfluoroalkyl substances (PFAS) with plastic (e.g., polypropylene, PP) and borosilicate glass materials, which are either recommended or advised against by prevalent analytical methods. Our results indicate that borosilicate glass minimally adsorbs short-chain, moderate-chain, and some long-chain PFAS with <11 perfluorinated carbons, maintaining the integrity of PFAS solutions. The ratios of PFAS concentrations in solutions contained in borosilicate glass compared to those in solutions unaffected by laboratory ware interaction showed minimal deviation, with most compounds displaying values within the established acceptable limits of 87 % to 107 % for C3‒C10 PFAS. Similarly, PP tubes, syringes, and pipette tips also demonstrated minimal or moderate interactions: perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) showed relatively consistent recoveries in PP syringes and pipette tips, ranging from 96 % to 107 % and minimal adsorption to PP centrifuge tubes during a 105-h contact period. Both materials, however, showed significant adsorption of the longest-chain PFAS in this study (C11), pointing to enhanced adsorption due to their hydrophobic nature. However, microfilters demonstrate significant adsorption of long-chain PFAS, including PFOA and PFOS. We developed a Gradient Flush Syringe Method to mitigate adsorption losses on syringe filters, achieved a significant reduction in C11 PFAS retention on filters from >90 % to nearly 0.01 %. Methanol-induced matrix effects were also studied, showed that increasing methanol concentrations led to artificially increasing the analyzed concentration of short-chain PFAS from the true concentration.