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.
SourceAvailable from: Mahnaz Ghambarian[Show abstract] [Hide abstract]
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. DOI:10.1007/s10337-013-2604-6 · 1.37 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: A three-phase hollow fiber liquid-phase microextraction (HF-LPME) was used to determine the trace amounts of Lead (II) in environmental water and tea drinks. In this approach, green solvent ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM]PF6) was used as membrane carrier that dissolved in hollow fiber pores. 1-(2-Pyridylazo)-2-naphthol (PAN) was placed in aqueous solution to form hydrophobic complex with Pb(II). Ethylene diamine tetraacetic acid (EDTA) was used as stripping agent that it can form water-soluble complex with Pb(II). After extraction, the acceptor solution was directly injected into the graphite furnace atomic absorption spectrometry (GF-AAS) for analysis. Some important parameters that influence the extraction efficiency were investigated, such as PAN concentration, pH, EDTA concentration, stirring rate, extraction time, and interfering metal ions. Under the optimized conditions, an enrichment factor (EF) of 210 and a limit of detection (LOD) of 0.004 ng mL−1 were obtained. The calibration curve was linear in the range of 0.05–0.5 ng mL−1 (R = 0.999). The relative standard deviation (RSD) at the 0.12 ng mL−1 Pb(II) level is 4.5 % (n = 6). The proposed method was successfully applied to determination of Pb(II) in environmental water and tea drinks samples with satisfactory recoveries in the range of 94–105 %.Journal of the Iranian Chemical Society 03/2015; 12(3). DOI:10.1007/s13738-014-0493-8 · 1.41 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: A new sample preparation technique named as fast agitated directly suspended droplet microextraction (FA-DSDME) was proposed as an improved version of directly suspended droplet microextraction (DSDME) for the extraction and pre-concentration of wide-range organophosphorus pesticides (OPPs) from human blood prior to liquid chromatography tandem mass spectrometric (LC-MS/MS) analysis. In this method, instead of protecting the unwanted rupturing of extraction droplet (organic solvent), it was deliberately splintered into fine droplets by providing automated high-speed agitation to the biphasic extraction system (extraction solvent and sample solution). Fine organic droplets were then recollected into one, not by using a centrifuge machine but just by giving a very slow stirring to the bottom of the extraction system. The present method has surmounted the problem of prolonged extraction time associated with old DSDME. Under optimum extraction conditions, the method showed good sensitivity with low detection limits ranging from 0.0009 to 0.122μgL(-1). Mean recoveries were achieved in the range of 86-109% at three levels of spiking concentration (low, middle and high) from linearity range of individual analyte. Intra-day and inter-day precisions were ≤4.68 and ≤9.57 (%RSD) respectively. Enrichment factor (EF) for each analyte varied from 30 to 132 which prove the ability of this technique to pre-concentrate the extracted analytes up to a good extent. The sample matrices have shown an insignificant influence on method's sensitivity. The proposed method may find immense use in epidemiological, toxicological, regulatory and forensic laboratories. Copyright © 2014 Elsevier B.V. All rights reserved.Journal of Chromatography A 12/2014; 1377. DOI:10.1016/j.chroma.2014.12.006 · 4.26 Impact Factor