Dispersive liquid-liquid microextraction for the preconcentration and determination of some organic sulfur compounds in aqueous samples

Abstract

In this study, dispersive liquid-liquid microextraction was developed for preconcentration of some organic sulfur compounds in aqueous samples. In this extraction method, 1.0 cm3 acetonitrile (as dispersive solvent) containing 12.0 mm3 chlorobenzene (as extraction solvent) was rapidly injected into the water sample containing analytes, and a cloudy solution was formed. The cloudy state resulted from the formation of fine droplets of chlorobenzene, which have been dispersed in bulk aqueous sample. After centrifugation (2 min at 5,000 rpm), these droplets were sedimented in the bottom of the conical test tube (5 ± 0.2 mm3). Then 2.0 mm3 of sedimented phase containing preconcentrated analytes was injected into the gas chromatograph with flame ionization detector. The parameters affecting the extraction efficiency have been evaluated and optimized. Under the optimum conditions, the limits of detection and preconcentration factors were obtained in the range of 0.1–0.9 μg dm−3 and 564–768, respectively. The calibration graphs were linear in the range of 1–200 μg dm−3. The relative standard deviations at 100 μg dm−3 concentration levels of analytes were found to be less than 10%. Finally, the accuracy of the proposed method was evaluated by extraction and determination of organic sulfur compounds from different water samples such as river, tap, and sea waters, and satisfactory results were obtained.