A simple and reliable workflow was established here for analyzing 45 PFAS compounds in both potable and non-potable waters. The target analytes included C2 to C14 perfluoroalkyl carboxylic acids (PFCA); C1 to C13 perfluoroalkyl sulfonic acids (PFSA); fluorotelomer carboxylic acids and sulfonic acids; perfluorooctane sulfonamides and sulfonamidoacetic acids; and per- and polyfluoroether carboxylic acids and sulfonic acids. Method suitability was evaluated in terms of linearity, accuracy, precision, and suitability for a range of water types. The method produced exceptional chromatographic performance, providing a tool for comprehensive PFAS analysis that overcomes the challenges associated with conventional reversed-phase liquid chromatography (RPLC).<\/p>\n\n\n\n
Ultrashort-chain per- and polyfluoroalkyl substances (PFAS) are small, very polar compounds with carbon chain lengths shorter than C4 (Figure 1). Their ubiquitous presence and high levels 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 ultrashort-chain and longer chain PFAS together in water samples to comprehensively assess the full spectrum of PFAS contamination. Methods allowing concurrent analysis of C1-C14 PFAS will be important tools in PFAS testing because they will allow a better understanding of environmental fate and potential human exposure, which is critical to developing effective regulations and remediation strategies.<\/p>\n\n\n\n
The development of comprehensive PFAS methods that include ultrashort-chain compounds is challenging because the high polarity of ultrashort-chain PFAS makes it difficult to obtain adequate retention with an RPLC method and C18 column, which is the typical approach for analyzing C4 and longer PFAS in water. Obtaining adequate retention and separation from matrix interferences is particularly problematic for early eluting compounds, such as TFA. GC-MS has been used for analyzing TFA and C4-C6 PFCA in water samples, but it requires an extra step for PFCA derivatization and does not allow simultaneous analysis of PFSA [1]. Ultrashort-chain PFAS have also been analyzed using anion-exchange LC, but method run times exceed 20 minutes and broad peaks were observed [2]. We have previously developed a rapid method for the analysis of ultrashort- and short-chain PFAS in water samples using a hybrid HILIC and ion-exchange LC column [3], but it did not incorporate long-chain PFAS. More recently, we developed a method to quantify C1 to C10 PFAS in human plasma and serum utilizing a polar-embedded alkyl phase LC column [4]. Based on the effectiveness of that method, we used it as a starting point for the current study, which aims to develop a new method for testing a broader range of PFAS in water matrices.<\/p>\n\n\n\n
The method developed here uses an LC column with a polar-embedded alkyl stationary phase to ensure adequate retention of early eluting polar compounds. In addition, the column is made with hardware treated with an inert coating, which improves sensitivity by preventing any unwanted analyte interactions with the stainless-steel column. Using this Ultra IBD Inert column, 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. Method performance was assessed for linearity, accuracy, precision, and suitability across a wide range of potable and non-potable water matrices.<\/p>\n\n\n