Determination of organic sulfurcontaminants using hollow fiber-protected liquid-phase microextraction coupled with gas chromatography

A simple and solvent-minimized sample preparation technique based on hollow fiber-protected liquid-phase microextraction has been developed for extraction of fifteen organic sulfur compounds (OSCs) from aqueous samples. Analysis of the extracted OSCs was performed by gas chromatography equipped with mass spectrometry (GC–MS) and/or flame photometric detectors (GC-FPD). Three µL of organic solvent located in the lumen of hollow fiber was used to extract OSCs from an 8 mL of aqueous sample. Several parameters influencing extraction efficiency such as salt concentration, stirring speed, temperature, sample volume, organic phase volume and extraction time were studied and optimized using super-modified simplex method. Under optimized conditions (extraction solvent (toluene) Extraction time (15 min ), salt addition (4 % w/v), stirring rate (1200 rpm), sample volume (8 ml SV), organic solvent volume (3.3 µl) and extraction temperature (35oC)) the limits of detection (LODs) varied from 0.1 to 8.7 µg L-1 and 0.7 to 99.4 µg L-1 for GC-FPD and GC-MS, respectively. The calibration graphs were linear over three orders of magnitude for most of the studied OSCs. The relative standard deviations (RSDs) for inter- and intra-day analysis were in the range of 5 to 10%, and the relative recoveries of the analytes from the three different real water samples were better than 83%. The results were compared with those obtained using direct single drop microextraction (Direct-SDME) and headspace single drop microextraction (HS-SDME) methods. The proposed method is reliable and can be considered useful for routine monitoring of the OSCs in surface water samples.