PFAS is short for per- and polyfluoroalkyl substances, also known as PFC (perfluorinated chemicals or perfluorocarbons) and PFT (perfluorinated tensides).
PFAS are used in consumer and industrial processes around the world and can accumulate in water, soil and living organisms. In everyday life, we encounter PFAS in pesticides, food packaging or impregnation sprays, for example. Since exposure to PFAS is associated with health risks, proper monitoring of these chemicals is essential. PFAS in drinking water e.g. can be analysed by SPE as a sample preparation method and a subsequent HPLC analysis.
Specifically, per- and polyfluorinated chemicals are a group of persistent and bioaccumulative anthropogenic pollutants that are characterized by a linear aliphatic backbone, a high degree of fluorination and often by carboxylic or sulfonic acid functionality. The substance group comprises more than 4,700 different substances. The organic compounds consist of carbon chains of different lengths in which the hydrogen atoms are completely (perfluorinated) or partially (polyfluorinated) replaced by fluorine atoms. PFAS are divided into long-chain and short-chain PFAS. Short-chain PFAS include, for example, perfluorinated carboxylic and sulfonic acids and the corresponding precursor compounds with less than seven or six perfluorinated carbon atoms.
In PFAS analysis, suitable vials and closures for this application are crucial. Adsorption effects of glass and possible contaminations of the sample by particles from the septa may put your analysis results at risk. Vials for PFAS analysis are ideally made of Polypropylene, because here - in contrast to glass bottles or silanized glass bottles - the adsorption effects are low and therefore the signal strengths of the analytes are high. Possible contamination by the plastic of the bottles or the septa material can be neglected: Even with PFBA, the detection rate is below 1%. Bottles suitable for PFAS analyses are available in different versions. For example, 1.5 mL threaded bottles N 9 with filling markings, 0.3 mL threaded bottles N 9 with inner cone or 0.3 mL snap ring bottles N 11 with inner cone are available.
Also, caps made of PP or PE with fluorine-free septa are recommended for reliable PFAS analysis. Septa with a polyimide coating instead of a PTFE lamination are ideal for the analysis of fluorinated / halogenated organic compounds and prevent any migration of fluorine into the sample. Various model variants are available, such as N 9 screw caps or N 11 snap ring caps.
Special phases for SPE enrichment of PFAS from water, textiles and sediments (contaminated soils) are a valuable tool in PFAS analysis. Polymeric combination phases with weak anion exchanger and highly porous spherical particles are used for solid phase extraction (SPE). Especially for perfluorinated surfactants, mixed-mode SPE columns with excellent recoveries, especially for the preconcentration of acidic (strong acids with pKa < 1) analytes are recommended. You will also find suitable SPE cartridges from Waters in our range. Oasis WAX for PFAS analysis is a water-wettable reversed-phase polymer with weak anion-eXchange in mixed mode, providing unparalleled purity, consistency and quality for sample analysis in drinking water, groundwater, surface water, wastewater, soil, food and other complex matrices.
Suitable HPLC columns for PFAS analysis are, for example, hydrophobic C18 phases with strong polar selectivity for better retention of early eluting substances. Nucleoshell RP 18plus columns from Macherey Nagel (for example EC 50/2 or EC 100/2) consist of silica gel particles of core-shell technology and show excellent performance under highly aqueous conditions. This stationary phase is used for challenging analytical separations, especially for polar compounds, and is ideal for the analysis of PFAS.