Micro solid-phase extraction for the analysis of per- and polyfluoroalkyl substances in environmental waters

Growing concern over the environmental and health impacts of per- and polyfluoroalkyl substances (PFASs) has led to the development of increasingly stringent regulatory guidelines. To meet these guidelines for the determination of PFASs in surface-water, solid-phase extraction (SPE) is commonly implemented for clean-up and pre-concentration of samples. In this paper a micro-SPE method for the clean-up and pre-concentration of PFASs from surface-water was developed. A micro-SPE packing phase was created to retain 13 long and short chain PFAS after examining combinations of four 3 µm particle size sorbents, with the optimal phase consisting of a 50:50 mixture of C18 and aminopropyl silica. Micro-SPE achieved similar results to conventional SPE methods while reducing sample preparation time to 5 min and using only 2 mL of sample. The method was validated using spiked recoveries (100 ng L^-1) from PFAS contaminated surface-water samples with recoveries ranging from 86% to 111% and relative standard deviations below 18%. Concentrations of the PFASs in the samples ranged from below the limit of quantification to 898 ± 15 ng L^-1. Automation of sample preparation, including the micro-SPE extraction, was also demonstrated. These results show the potential for automated micro-SPE to replace conventional SPE, with the decreases in sample preparation time, sample and solvent volumes crucial for incorporation into routine analyses in commercial laboratories.