Development of Liquid Phase Microextraction Method Based on Solidification of Floated Organic Drop for Extraction and Preconcentration of Organochlorin 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: 4.51). 10/2008; 626(2):166-73. DOI: 10.1016/j.aca.2008.08.001
Source: PubMed


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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    • "Consequently, residue analyses of OCPs in waters and soils by developing analytical procedure continue to be an active area of research in recent years (Santos & Galceran, 2004). Trace analysis of OCPs in water is usually performed by gas chromatography (GC) combined with a previous an extraction or a pre-concentration step including traditional liquid–liquid extraction (LLE) (Barcelo´, 1993, Fatoki & Awofolu, 2003; Tahboub et al., 2005), solid phase extraction (SPE) (Aguilar et al., 1996; 1997), solid phase microextraction (SPME) (Page & Lacroix, 1997; Aguilar et al., 1999; Tomkins & Barnard, 2002; Li et al., 2003; Dong et al., 2005) and the more recently developed liquid phase microextraction under different names, i.e., dispersive liquid–liquid microextraction (DLLME) (Cortada et al., 2009a; Leong & Huang, 2009; Tsai & Huang, 2009), liquid-phase microextraction (LPME) (Huang & Huang, 2007; Farahani et al., 2008), single-drop microextraction (SDME) (Cortada et al., 2009b), polymer-coated hollow fiber microextraction (PC-HFME) (Basheer et al., 2004), stir bar sorptive extraction (SBSE) (Leo´n et al., 2003; Pe´rez-Carrera et al., 2007), ultrasound 61 recovery of analytes. However, general drawbacks of this method are difficult to automate and it requires using a dispersive solvent which usually decreases the partition coefficient of analytes into the extraction solvent (Rezaee et al., 2006; Pena-Pereira et al., 2009). "

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