Ionic liquid based in situ solvent formation microextraction coupled to thermal desorption for chlorophenols determination in waters by gas chromatography/mass spectrometry.

A simple and efficient method for the determination of ten chlorophenols (including mono, di, tri, tetra and pentachlorophenols) in water samples is presented. The analytical method is based on a previous derivatization of the target compounds with acetic anhydride, being the derivatized compounds finally isolated/preconcentrated by an in situ solvent formation microextraction. Later on the extractant (an ionic liquid) containing the analytes is recovered by centrifugation and thermally desorbed. The analytes are finally separated and determined by gas chromatography/mass spectrometry. The main variables involved in the extraction and thermal desorption steps have been studied in depth. Once evaluated, the analytical method has been characterized in terms of linearity, sensitivity, precision and accuracy. The limits of detection were in the range from 60 ng L(-1) (4-chlorophenol) to 440 ng L(-1) (pentachlorophenol) while the precision, expressed as relative standard deviation, was in the interval from 4.5% (2,6-dichlorophenol) to 9.9% (3-chlorophenol). In addition, acceptable recovery values were obtained in samples of different nature, including river, tap and reservoir water samples.