Introduction (120): Ultrashort-chain (USC) per- and polyfluoroalkyl substances (PFAS) are small and very polar compounds with carbon chain lengths shorter than C4. Their ubiquitous and high levels of occurrence in environmental aquatic systems are emerging as a significant concern, rivaling the well-established issues associated with long-chain PFAS contamination. Therefore, it is important to analyze both USC and long-chain PFAS together in water samples to comprehensively assess and address the full spectrum of PFAS contamination. In this study, a simple and reliable workflow was developed for the simultaneous analysis of C1 to C14 perfluoroalkyl carboxylic and sulfonic acids, along with other groups of PFAS, in both potable and non-potable waters.
Methods (120): A dilute-and-shoot workflow was evaluated by accuracy and precision analysis of fortified tap water, bottled water, and treated sewage wastewater. Calibration standards were prepared in reverse osmosis water ranging from 1-1000 ng/L. Five and eighteen mass-labeled standard mixtures were added and served as quantitative and extracted internal standards, respectively. Both standard and water samples were diluted two-fold with methanol containing 1% acetic acid for LC-MS/MS analysis. The chromatographic separation was conducted using a polar-embedded reversed-phase LC column with an inert coating on the hardware. Additional potable and non-potable waters collected from various source waters were tested to further demonstrate that the established workflow is suitable for the accurate quantification of targeted PFAS in a wide range of water matrices.
Preliminary Data: (300) The high polarity of ultrashort-chain PFAS poses a challenge to current analytical practices based on reversed-phase liquid chromatography due to insufficient chromatographic retention. This study demonstrated that a polar-embedded reversed-phase column allows for the simultaneous analysis of ultrashort-chain and long-chain PFAS. The targeted analytes included C2 to C14 perfluoroalkyl carboxylic acids, C1 to C13 perfluoroalkyl sulfonic acids, fluorotelomer carboxylic acids and sulfonic acids, perfluorooctane sulfonamides and sulfonamidoacetic acids, and per- and polyfluoroether carboxylic acids and sulfonic acids.
Employing quadratic regression (1/x weighted), all analytes exhibited acceptable linearities with r2 >0.995 and deviations <30%. The linearity ranges varied among analytes, spanning from 1 ppt to 1000 ppt, with some variation observed at the lowest calibration concentration. Accuracy and precision were assessed using fortified water samples at concentrations of 2, 4, 10, 50, and 250 ppt. Three batches of analyses were conducted on different days, totaling nine repetitions at each fortified level. The results showed that all analytes exhibited recovery values within the range of 70-130% across all fortification levels. Satisfactory method precision was demonstrated with %RSD values within 20%. Additionally, the results indicated that all extracted internal standards had recovery values within 30% of the nominal concentration.
The established workflow was applied to measure targeted PFAS in a variety of source waters including five tap waters, three bottled waters, a natural spring water, two well waters, three creek waters, one treated sewage wastewater, one hospital effluent water, one metal finisher effluent water, and one chemical manufacturer effluent water. Consistent with the accuracy and precision analysis, the recoveries of extracted internal standards were within 30% of the nominal concentration across all source waters. This demonstrated that the established method was suitable for accurate measurement of targeted PFAS in a wide range of water matrices.
Novel Aspect (20): A unique method was developed to incorporate ultrashort-chain compounds into comprehensive PFAS analysis in waters.
