In situ generated ionic liquid and dispersive liquid-phase microextraction to determine chlorobenzenes in environmental samples by gas chromatography-mass spectrometry

Abstract

An in situ generated ionic liquid dispersive liquid-phase microextraction procedure (IL-DLPME) is proposed for the preconcentration of ten chlorobenzene compounds (CBs). Direct microvial insert thermal desorption allowed the direct analysis of the IL extract by gas chromatography with mass spectrometry (GC–MS). The developed procedure was applied to the analysis of water and soil samples. An ultrasound assisted extraction (UAE) stage was applied to isolate the analytes from the soil matrices into an ammonium acetate buffer solution, before the preconcentration stage. Several factors affecting microextraction efficiency (volume of ionic components used in the extractant phase and the volume and salt content of the aqueous phase), and the thermal desorption step (desorption time and temperature, and gas flow rate) were studied. Quantification of the water samples was carried out against aqueous standards, while in the case of soils the standard additions method was used, taking into consideration the detected matrix effect. Detection limits in the 0.5–7.2 ng L−1 and 8.4–252 ng kg−1 ranges, depending on the analyte, were obtained for waters and soils, respectively. The accuracy of the method was checked using a certified reference material and by recovery studies. Concentrations in the 2.7–256 ng L−1 and 1.5–50 ng g−1 ranges were obtained for some CBs in waters and soils, respectively.