Determination of perfluorocarboxylic acids in aqueous matrices by ion-pair solid-phase microextraction–in-port derivatization–gas chromatography–negative ion chemical ionization mass spectrometry

A rapid, selective and simple analytical procedure using tetrabutylammonium as ion pair in conjunction with solid-phase microextraction followed by in-port derivatization–GC–negative ion chemical ionization mass spectrometry was developed. The procedure allows an accurate determination of perfluoroalkylcarboxylic acids in aqueous samples at ng L−1 levels (i.e. method detection limit 20 ng L−1 for perfluorodecanoic acid) improving previous GC methods in terms of analysis time and sensitivity. Ammonia as reagent gas in the negative ion chemical ionization mass spectrometry increased the sensitivity at least 3-fold compared to methane for perfluorocarboxylic acid butyl esters. The developed procedure was successfully applied to effluents from wastewater treatment plants (i.e. 0.05–8.2 μg L−1) and harbor seawaters.