Application of ultrasound-assisted emulsification-micro-extraction for the analysis of organochlorine pesticides in waters

Ultrasound-assisted emulsification-micro-extraction (USAEME) procedure was developed for the determination of different organochlorine pesticides (OCPs) in water samples by gas chromatography with μ-electron capture detection (GC-μECD). After the determination of the most suitable extraction solvent and its volume, parameters such as extraction time, centrifugation time and ionic strength of the sample were optimized by using a 23 factorial experimental design. For 10 mL of water sample, the optimized USAEME procedure used 200 μL of chloroform as extraction solvent, 15 min of extraction without ionic strength adjustment at 25 °C and 5 min of centrifugation at 4000 rpm. Limits of detection ranged from 0.002 to 0.016 μg L−1. Mean recoveries of OCPs from fortified water samples are over 96% for three different fortification levels between 0.5 and 5 μg L−1 and relative standard deviations of the recoveries are below 9%. The developed procedure was successfully applied for real water samples (i.e., tap water, well water, surface (lake) water, domestic and industrial wastewater). Performance of the procedure was compared with those involving traditional liquid–liquid extraction and solid-phase extraction. The result demonstrates that the USAEME procedure is viable, rapid and easy to use for analysis of OCPs in water samples.