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A robust extraction method against the variations of sample ionic strength viz. ionic liquid-based ultrasound-assisted in situ solvent formation microextraction (IL-UA-ISFME) was coupled for the first time with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) and successfully used as a more sustainable approach for the determination of meloxicam (MEL) in human plasma. Herein, a hydrophobic IL (1-butyl-3-methylimidazolium hexafluorophosphate) was formed by adding a hydrophilic IL (1-butyl-3-methylimidazolium tetrafluoroborate) to aqueous sample solution containing an ion-exchange reagent (sodium hexafluorophosphate). The target analyte was transferred into the IL medium while the extraction solvent was completely dispersed into the sample using ultrasonic irradiation and then, the settled enriched phase was injected to HPLC. Firstly, main factors affecting the microextraction performance were evaluated and optimized. The linearity was in the range of 5-1,500 ngmL-1 with regression coefficient corresponding to 0.997. Limits of detection (LOD; signal-to-noise ratio (S/N) = 3) and quantification (LOQ, S/N = 10) were 1 and 5 ngmL-1, respectively. An acceptable recovery range of 82.1-93.6% and satisfactory intra-assay (3.6-4.8%, n = 6) and inter-assay (3.3-5.1%, n = 9) precision as well as remarkable sample clean up exhibited good efficiency of the method. The freeze-thaw stability study was performed for samples and standard solutions. To study the applicability of the proposed method, it was employed for the determination of MEL in human plasma after oral administration of the drug and some pharmacokinetic data were achieved. The technique proved to be accurate and reliable for the screening intentions. [ABSTRACT FROM AUTHOR]

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 sensitive methodology based on liquid–liquid–liquid microextraction (LLLME) followed by high-performance liquid chromatography-ultraviolet detection (HPLC-UV) has been successfully developed for the determination of atorvastatin (AT) in human plasma. AT was first extracted from 4.5mL acidic aqueous sample (diluted plasma, donor phase, pH 1) at temperature 45°C through 400μL 1-octanol for 4.5min, while being agitated by a stirring bar at 1250rpm. Then, a 5.5μL free suspended basic aqueous droplet (acceptor phase, pH 10) was delivered to the top-center position of the organic membrane. The mixture was stirred at 650rpm for 7.5min and the analyte was back-extracted into the droplet. Finally, the acceptor phase was taken into a microsyringe and injected directly into the HPLC. An enrichment factor of 187 along with substantial sample clean up was obtained under the optimized conditions. The calibration curve showed linearity in the range of 1–500ngmL−1 with regression coefficient corresponding to 0.996. Limits of detection (S/N=3) and quantification (S/N=10) were 0.4 and 1ngmL−1, respectively. A reasonable relative recovery (91%) and satisfactory intra-assay (4.4–7.0%, n =6) and inter-assay (4.9–7.7%, n =8) precision illustrated good performance of the analytical procedure. This technique was eventually applied for the determination of AT in human plasma after oral administration of 40mg single dose of drug. The protocol proved to be highly cost-effective and reliable for the screening purpose. [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]