A rapid and sensitive assay of perfluorocarboxylic acids in aqueous matrices by headspace solid phase microextraction–gas chromatography–triple quadrupole mass spectrometry

The work aims at developing a rapid and sensitive method for the quantification of perfluorocarboxylic acids in aqueous matrices. The proposed analytical approach is based on the use of solid phase microextraction in headspace mode after a fast derivatization of the carboxylate function by propylchloroformate/propanol mixture. Several fibers were evaluated and the optimization of the parameters affecting the SPME process was carried out using a central composite design. The optimum working conditions in terms of response values were achieved by performing analysis with CAR/PDMS fiber at room temperature, without addition of NaCl, with a sample volume of 6 ml and an extraction time of 10 min. Assay of PFCAs was performed by using a gas chromatography–triple quadrupole mass spectrometry (GC–QqQ MS) system in negative chemical ionization mode with ammonia as reagent gas. An overall evaluation of all analytical parameters shows that the proposed method provides satisfactory results. In particular, the observed accuracies, ranging from 84.4% to 116.8%, and the RSD values in the range 0.4% and 14.5% confirm the effectiveness of the developed protocol in the assay of PFCAs content in aqueous matrices. Moreover, LOD and LOQ values ranging from 0.08 to 6.6 ng l−1 and from 0.17 to 14.3 ng l−1, respectively, can be considered very satisfactory. None of the compounds were detected in six samples of river collected in Calabria.

► A very rapid and automated procedure allowing higher-throughput screening is proposed.
► The joined use of alkylchloroformate and SPME allows one to minimize the presence of organic solvents in the final protocol.
► The obtained LODs and LOQs for PFHxA, PFHpA, PFOA and PFNA are the lowest values in literature.
► The specificity of the NCI-MS/MS acquisition mode improves the ability in analyte identification.