Optimization of temperature-controlled ionic liquid dispersive liquid phase microextraction combined with high performance liquid chromatography for analysis of chlorobenzenes in water samples

Temperature-controlled ionic liquid dispersive liquid phase microextraction (TCIL-DLPME) combined with high performance liquid chromatography-diode array detection (HPLC-DAD) was applied for preconcentration and determination of chlorobenzenes in well water samples The proposed method used 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)min][PF6]) as the extraction solvent The effect of different variables on extraction efficiency was studied simultaneously using an experimental design The variables of interest in the TCIL-DLPME were extraction solvent volume salt effect solution temperature extraction time centrifugation time and heating time The Plackett-Burman design was employed for screening to determine the variables significantly affecting the extraction efficiency Then the significant factors were optimized by using a central composite design (CCD) and the response surface equations were developed The optimal experimental conditions obtained from this statistical evaluation included extraction solvent volume 75 mu L extraction time 20 min centrifugation time 25 min heating time 4 min solution temperature 50 degrees C and no addition of salt Under optimal conditions the preconcentration factors were between 187 and 298 The limit of detections CLODS) ranged from 0 05 mu g L-1 (for 1 2-dichlorobenzene) to 0 1 mu g L-1 (for 1 2 3-trichlorobenzene) Linear dynamic ranges (LDRs) of 0 5-300 and 05-500 mu g L-1 were obtained for dichloro- and trichlorobenzenes respectively The performance of the method was evaluated for extraction and determination of chlorobenzenes in well water samples in micrograms per liter and satisfactory results were obtained (RSDs < 9 2%) (C) 2010 Elsevier B V All rights reserved