Ultra‐sensitive PFAS analysis according to EU and EPA regulations in drinking water

PFAS are highly present in the public posing threats to mankind and nature. Manufactured since the 1940s as water and grease repellents in consumer products, they are considered „forever chemicals”. With their persistent, bio‐accumulative, toxic (PBT) properties and ubiquitous presence in the environment and organisms, there is mounting evidence that PFAS exposure may generate adverse health effects. EPA and EU regulations exist for the routine monitoring of certain PFAS in water and od with individual legal limits in the sub‐ppt range. Reaching these limits in a routine and robust manner is a challenge. Presented is a routine targeted method by a novel, fast, robust and highly sensitive TQ exceeding the current regulations for reliable and confident PFAS quantification. A standard list of 40 PFAS was used for the performance evaluation. An Elute HT UHPLC was coupled to an EVOQ DART‐TQ+ (both Bruker, Bremen, Germany). The total runtime of the method incl. equilibration was 13.2 min with a gradient of 2 mM ammonium acetate in water and methanol on a Bruker Intensity Solo 2.0 100times2.0mm column and a Restek 50times2.0mm delay column. The TQ was operated in both polarities with source parameters and MRM transitions optimized. The scan speed was automatically calculated per compound with a minimum number of 12 spectra per peak and a dynamic window of 0.6 min per analyte. Since PFAS are present in a wide range of laboratory materials, solvents, instruments and equipment that utilized on a daily basis, contaminations are frequent and could be minimized by special material and lab care. In addition, we checked the matrix effect in the proposed method for drinking water by using different sources of water. A minimum background could be achieved by water type I which deionized water. Mobile phase compositions were optimized, different gradients and flow rate tested, and the equilibration time at the beginning of the injection to avoid accumulation. Typical LOQ reached for all PFAS were in the range of 0.1 ‐ 0.5 ppt. These limits are 10x lower than those required by the EU Drinking Water Directive (EU 2020/2184), a very high sensitivity in negative mode due to a novel multiplier geometry. The average LOQ for all compounds was 0.3 ppt. Linearities had typical values for R 2 ≥ 0.999. The system shows a high robustness with much reduced contamination and crosstalk for multiple injections. The method represents a robust, highly sensitive and fast analysis of PFAS with a total run time of 13 min according to and exceeding the current EU regulations.