Development of liquid phase microextraction method based on solidification of floated organic drop for extraction and preconcentration of organochlorine pesticides in water samples.
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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ABSTRACT: A fast and effective preconcentration method for extraction of organochlorine pesticides (OCPs) was developed using a homogeneous liquid–liquid extraction based on phase separation phenomenon in a ternary solvent (water/methanol/chloroform) system. The phase separation phenomenon occurred by salt addition. After centrifugation, the extraction solvent was sedimented in the bottom of the conical test tube. The OCPs were transferred into the sedimented phase during the phase separation step. The extracted OCPs were determined using gas chromatography–electron capture detector. Several factors influencing the extraction efficiency were investigated and optimized. Optimal results were obtained at the following conditions: volume of the consolute solvent (methanol), 1.0 mL; volume of the extraction solvent (chloroform), 55 μL; volume of the sample, 5 mL; and concentration of NaCl, 5 % (w/v). Under optimal conditions, the preconcentration factors in the range of 486–1,090, the dynamic linear range of 0.01–100 μg L−1, and the limits of detection of 0.001–0.03 μg L−1 were obtained for the OCPs. Using internal standard, the relative standard deviations for 1 μg L−1 of the OCPs in the water samples were obtained in the range of 4.9–8.6 % (n = 5). Finally, the proposed method was successfully applied for extraction and determination of the OCPs in water and fruit samples.Chromatographia 02/2013; 77(3-4):329-336. · 1.37 Impact Factor
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ABSTRACT: This article reports an alternative method for simultaneous extraction and determination of chlorpyrifos and its main degradation product 3,5,6-trichloro-2-pyridinol (TCP) in water samples which involves dispersive liquid–liquid microextraction based on solidification of floating organic droplet followed by high-performance liquid chromatography with ultraviolet detection. Methanol (1.0 mL) and 1-dodecanol (70 µL) were used as the disperser solvent and extraction solvent, respectively. After the floated extraction solvent had solidified in an ice bath, it was dissolved with methanol. Under the optimized conditions, enrichment factors for chlorpyrifos and TCP were 96 and 114, respectively. Linear calibration curves were obtained in the range of 1–50 µ g L −1, with correlation coefficients (R 2) > 0.9955. The limits of detection were 0.12 µ g L −1 for chlorpyrifos and 0.10 µ g L −1 for TCP. The recoveries of spiked real water samples ranged between 84.54% and 102.29%, with the relative standard deviation being 0.80–14.03%.Journal of Liquid Chromatography & Related Technologies 07/2014; 37(11). · 0.64 Impact Factor
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ABSTRACT: Modes and mechanisms of different kinds of LPMEs are discussed and summarized.•Applications of LPMEs in different natural product matrices analysis are summarized.•Future developments and applications of the LPMEs in complex sample analysis are prospected.Journal of Chromatography A 11/2014; 1368. · 4.26 Impact Factor