Development of liquid phase microextraction method based on solidification of floated organic drop for extraction and preconcentration of organochlorine pesticides in water samples

Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran.
Analytica chimica acta (Impact Factor: 4.52). 10/2008; 626(2):166-73. DOI: 10.1016/j.aca.2008.08.001
Source: PubMed

ABSTRACT A simple and efficient liquid-phase microextraction (LPME) in conjunction with gas chromatography-electron capture detector (GC-ECD) has been developed for extraction and determination of 11 organochlorine pesticides (OCPs) from water samples. In this technique a microdrop of 1-dodecanol containing pentachloronitrobenzene (internal standard) is delivered to the surface of an aqueous sample while being agitated by a stirring bar in the bulk of solution. Following completion of extraction, the sample vial was cooled by putting it into an ice bath for 5 min. Finally 2 muL of the drop was injected into the GC for analysis. Factors relevant to the extraction efficiency were studied and optimized. Under the optimized extraction conditions (extraction solvent: 1-dodecanol; extraction temperature: 65 degrees C; sodium chloride concentration: 0.25 M; microdrop and sample volumes: 8 muL and 20 mL respectively; the stirring rate: 750 rpm and the extraction time: 30 min), figures of merit of the proposed method were evaluated. The detection limits of the method were in the range of 7-19 ngL(-1) and the RSD% for analysis of 2 mugL(-1) of OCPs was below 7.2% (n=5). A good linearity (r(2)> or =0.993) and a relatively broad dynamic linear range (25-2000 ngL(-1)) were obtained. After 30 min of extraction, preconcentration factors were in the range of 708-1337 for different organochlorine pesticides and the relative errors ranged from -10.1 to 10.9%. Finally the proposed method was successfully utilized for preconcentration and determination of OCPs in different real samples.

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