Determination of chlorobenzenes in water by drop-based liquid-phase microextraction and gas chromatography-electron capture detection.

A drop-based liquid phase microextraction and gas chromatographic-electron capture detection (GC-ECD) method was described for the determination of chlorobenzenes including chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene and 1,2,3-trichlorobenzene in 5 ml of water. The method used 2 microl of n-hexane as extraction solvent, 5 min extraction time, a stirring rate of 600 rpm and sample ionic strength of 3 M maintained with sodium chloride at 25 degrees C (ambient temperature). The limits of detection (LODs) ranged from 0.004 microg l(-1) (for 1,3-dichlorobenzene) to 0.008 microg l(-1) (for monochlorobenzene). The dynamic linear range for all investigated chlorobenzenes was 1-50 microg l(-1). Recoveries of chlorobenzenes from fortified distilled water are over 90% for three different fortification levels (5, 15 and 45 microg l(-1)) and relative standard deviations of the recoveries are below 6%. Analysis of fortified (5 microg l(-1)) real water samples revealed that matrices had no adverse effect on extraction efficiency of proposed method. The recovery of fortified real water samples was from 90 to 94% with relative standard deviations below 6%.