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Dispersive solid-phase extraction followed by triethylsilyl derivatization and gas chromatography mass spectrometry for perfluorocarboxylic acids determination in water samples

Stróżyńska, Monika, Schuhen, Katrin
Journal of chromatography 2019 v.1597 pp. 1-8
carboxylic acids, derivatization, effluents, esterification, esters, gas chromatography-mass spectrometry, ion exchange, perfluorocarbons, perfluorooctanoic acid, solid phase extraction, water analysis, water treatment, Germany
A new, simple derivatization method for the determination of perfluorocarboxylic acids (PFCAs, C3-C12) in water is presented. The method is based on an acid-catalyzed esterification of perfluorinated carboxylic acids with triethylsilanol. During the reaction, a triethylsilyl ester is formed which can be easily analyzed by gas chromatography-mass spectrometry (GC–MS). The classic ion exchange solid phase extraction used for PFCAs (DIN 38407-42) has been significantly modified and adopted for the newly developed derivatization method. The new method offers a linear range from 8 to 10,000 ng l−1 for PFOA, with a limit of quantification ranging from 4 to 48 ng l-1 depending on the actual PFCA. Due to sample preparation simplicity, the presented method can be applied to form PFCAs esters prior to GC–MS analysis of water samples. The method was successfully applied in the analysis of effluents from two water treatment plants in Baden-Württemberg, Germany. Additionally, to confirm the laboratory evaluation, the standard solutions and samples were also measured by an external laboratory using LC–MS2.