National Environmental Monitoring Conference

The analysis of perfluorinated compounds (PFCs) in aqueous matrices, especially finished drinking water and ground water, has received much attention in recent years. The USEPA has issued health advisories specifically for PFOA and PFOS and the occurrence data from the third Unregulated Contaminant Monitoring Rule (UCMR3) indicates a continuing need for this specific analysis. Using EPA method 537, a 250mL water sample is extracted by SPE using a polystyrenedivinylbenzene (SDVB) sorbent. This extraction is very robust and very sensitive to the low ng/L levels using only 2-10uL injections. However, method 537 does take a considerable amount of time to perform the SPE and because the methanol extract has to be evaporated to dryness and then reconstituted. Online SPE has been shown to be a excellent technique for analyzing aqueous matrices because it bypasses the SPE time mentioned previously, increasing sample throughput significantly. Additionally, it can be just as sensitive when injecting volumes in the range of 5.0mL or more. The performance of three different online SPE sorbents was evaluated for this application; Strata C18-E, Strata-X, and Strata-X-AW. Four PFC analyte classes were evaluated; Perfluoroalkyl acids (PFAAs), perfluorosulfonates (PFSAs), perfluorosulfonamidoacetic acids (FOSAAs), and fluorotelomersulfonates (FTSs). We present data on the pros and cons of each sorbent as well as sensitivity, accuracy, and precision.