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A simple and sensitive method based on a modified hollow-fiber liquid-phase microextraction followed by gas chromatography-mass spectrometry has been successfully developed for the extraction and simultaneous derivatization of some nitrophenols (NPs) in soil and rain samples. Microwave-assisted solvent extraction was used for the extraction of NPs from the soil, while the rain sample was directly applied to the previously mentioned method. Briefly, in this method, the analytes were extracted from aqueous samples into a thin layer of organic solvent (dodecane + 10 % tri- n-octylphosphine oxide) sustained in the pores of a porous hollow fiber. Then, they were back-extracted using a small volume of organic acceptor solution (25 μl; 10 mg/L N-methyl- N-(trimethylsilyl)trifluoroacetamide, as derivatization reagent, in acetonitrile) that was located inside the lumen of the hollow fiber. Under the optimized extraction conditions, enrichment factors of 255 to 280 and limits of detection of 0.1 to 0.2 μg/L ( S/ N = 3) with dynamic linear ranges of 1-100 μg/L were obtained for the analytes. The accuracy of the approach was tested by the relative recovery experiments on spiked samples, with results ranging from 93 to 113 %. The method was shown to be rapid, cost-effective, and potentially interesting for screening purposes. [ABSTRACT FROM AUTHOR]

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 5min. Finally 2μL 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°C; sodium chloride concentration: 0.25M; microdrop and sample volumes: 8μL and 20mL respectively; the stirring rate: 750rpm and the extraction time: 30min), figures of merit of the proposed method were evaluated. The detection limits of the method were in the range of 7–19ngL−1 and the RSD% for analysis of 2μgL−1 of OCPs was below 7.2% (n =5). A good linearity (r 2 ≥0.993) and a relatively broad dynamic linear range (25–2000ngL−1) were obtained. After 30min 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. [Copyright &y& Elsevier]

Abstract: A simple and efficient liquid-phase microextraction (LPME) technique was developed using directly suspended organic microdrop coupled with gas chromatography–mass spectrometry (GC–MS), for the extraction and the determination of phthalate esters (dimethyl phthalate, diethyl phthalate, diallyl phthalate, di-n-butyl phthalate (DnBP), benzyl butyl phthalate (BBP), dicyclohexyl phthalate and di-2-ethylhexyl phthalate (DEHP)) in water samples. Microextraction efficiency factors, such as nature and volume of the organic solvent, temperature, salt effect, stirring rate and the extraction time were investigated and optimized. Under the optimized extraction conditions (extraction solvent: 1-dodecanol; extraction temperature: 60°C; microdrop volume: 7μL; stirring rate: 750rpm, without salt addition and extraction time: 25min), figures of merit of the proposed method were evaluated. The values of the detection limit were in the range of 0.02–0.05μgL−1, while the R.S.D.% value for the analysis of 5.0μgL−1 of the analytes was below 7.7% (n =4). A good linearity (r 2 ≥0.9940) and a broad linear range (0.05–100μgL−1) were obtained. The method exhibited enrichment factor values ranging from 307 to 412. Finally, the designed method was successfully applied for the preconcentration and determination of the studied phthalate esters in different real water samples and satisfactory results were attained. [Copyright &y& Elsevier]

Abstract: Solid drop based liquid-phase microextraction (SDLPME) is a novel sample preparation technique possessing obvious advantages of simple operation with a high pre-concentration factor, low cost and low consumption of organic solvent. SDLPME coupled with gas chromatography (GC), high-performance liquid chromatography (HPLC), and atomic absorption spectrometry (AAS) has been widely applied to the analyses of a different variety of samples. The basic principles, parameters affecting the extraction efficiency, and the latest applications of SDLPME are reviewed in this article. [Copyright &y& Elsevier]

Abstract: A simple and efficient method (known as dispersive liquid–liquid microextraction (DLLME)) combined with gas chromatography–flame ionization detector (GC–FID) has been successfully developed for the extraction and determination of mononitrotoluenes (MNTs) in aquatic samples. The effects of parameters such as the nature and volume of the extracting and disperser solvents on the microextraction efficiency were also investigated. The volume of the extracting solvent (chlorobenzene) and that of the disperser solvent (acetonitrile) were obtained to be equal to 10.0μL and 0.5mL, respectively, in the optimal microextraction conditions established. Under the optimal conditions, the detection limit of the method was 0.5μgL−1 and the relative standard deviations (RSDs%) for determination of the MNTs were in the range of 8.0–9.4. Linearity was found to be in the range of 1–1000μgL−1; also, the pre-concentration factors were in the range of 351–357. Finally, the method was applied to determine the trace amounts of the MNTs in several real aquatic samples and satisfactory results were obtained. [Copyright &y& Elsevier]