Dispersive solid-phase extraction followed by triethylsilyl derivatization and gas chromatography mass spectrometry...

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.