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Extracting Solvent (extracting + solvent)
Selected AbstractsQuantitation of valproic acid in pharmaceutical preparations using dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection without prior derivatizationDRUG TESTING AND ANALYSIS, Issue 7 2010Hamid Reza Sobhi Abstract Dispersive liquid-liquid microextraction (DLLME), coupled with gas chromatography-flame ionization detection (GC-FID), has been successfully used for the extraction and determination of valproic acid (VPA) in pharmaceutical preparations. In the developed method, an appropriate mixture of extracting and disperser solvents was rapidly injected into an aqueous sample. Having formed a cloudy solution, the mixture was centrifuged and then the extracting solvent was sedimented at the bottom of a conical test tube. The extract was then injected into a GC system directly, without any further pretreatment. Initially, microextraction efficiency factors were optimized and the optimum experimental conditions found were as follows: tetrachloroethylene (9.0 µL) as extracting solvent; acetone (1.0 mL) as disperser solvent; 5 mL acidic aqueous sample (pH 1) without salt addition. Under the selected conditions, the calibration curve showed linearity in the range of 0.1,5.0 mg/L with regression coefficient corresponding to 0.9998. The limit of detection was found to be 0.05 mg/L. Finally, the method was applied for the determination of VPA in two different pharmaceutical preparations. A reasonable intra-assay (3.9,10.8%, n = 3) and inter-assay (5.6,11.4%, n = 3) precision illustrated the good performance of the analytical procedure. The protocol proved to be rapid and cost-effective for screening purposes. Copyright © 2010 John Wiley & Sons, Ltd. [source] Capillary electrophoretic chiral separation of hydroxychloroquine and its metabolites in the microsomal fraction of liver homogenatesELECTROPHORESIS, Issue 5-6 2006Carmem Dickow Cardoso Abstract A rapid, selective, and low-cost chiral capillary electrophoretic method was developed for the simultaneous analysis of hydroxychloroquine (HCQ) and its three chiral metabolites: desethylchloroquine (DCQ), desethylhydroxychloroquine (DHCQ), and bisdesethylchloroquine (BDCQ) in the microsomal fraction of liver homogenates. After liquid,liquid extraction using toluene as extracting solvent, the drug and metabolites were resolved on a fused-silica capillary (50,,m ID, 50,cm total length, and 42,cm effective length), using 100,mmol/L of Tris/phosphate buffer, pH,9.0 containing 1% w/v sulfated-,-CD and 30,mg/mL hydroxypropyl-,-CD. Detection was carried out at 220,nm. The extraction procedure was efficient in removing endogenous interferents, and low values (,15%) for CVs and deviation from theoretical values were demonstrated for both within-day and between-day assays. The quantitation limit was 125,ng/mL with linear response over the 125,2000,ng/mL of concentration range for all metabolites. After validation, the method was used for an in vitro metabolism study of HCQ. The major HCQ metabolite formed by microsomal enzymes was (,)-(R)-DHCQ. [source] Supercritical extraction of borage seed oil coupled to conventional solvent extraction of antioxidantsEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 11 2008Carmen Soto Abstract This paper describes the extraction of borage seed oil by supercritical carbon dioxide (SC-CO2) and the further extraction of antioxidants from the SC-CO2 -defatted borage meal with organic solvents (water, methanol, ethanol and ethyl acetate). The optimal conditions for oil extraction were obtained at 303 and 323,K at 200,bar, 2.5,h and a continuous flow of CO2 of 1.5,L/h introduced through the bottom when the operating pressure and temperature were reached, attaining a yield of 60%. Borage oil is rich in unsaturated fatty acids; oleic acid, linoleic acid and linolenic acid accounted for 74% of the total fatty acid content under the above conditions. The highest extraction yield was achieved using water or methanol as extracting solvent from the SC-CO2 -defatted borage meal at 303,K and pressures of 200 and 150,bar for water and methanol, respectively. The most potent extracts, according to all methods tested, were obtained with water and methanol. [source] Liquid chromatography-tandem mass spectrometry method for determination of Sirolimus coated drug eluting nano porous carbon stentsBIOMEDICAL CHROMATOGRAPHY, Issue 3 2010G. Rajender Abstract Liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has proved to powerful research tool due to its sensitivity, high selectivity, and high throughput efficiency..Sirolimus was extracted from plasma by two-step extraction procedure using chloroform as extracting solvent. Signal intensity was high using ESI+ source provided for the quantitation of samples. Chromatographic separation was performed on phenomenax C-18 column (250 × 4.60,mm 5microns).Mobile phase contains acetonitrile, water (80; 20 v/v) + 0.1% acetic acid, flow rate 1,mL/min. The retention time of Sirolimus 8.4,min, the total run time10,min. Linearity correlation coefficients (r2) curve was 0.997183.calibraction range 10,1000,ng/mL. The UV detection of Sirolimus was at 278(277.78) nm. Sirolimus coated drug eluting stents, MRM (Multiple reaction monitoring) transition of Sirolimus m/z 936.83,208.84 was selected to obtain maximum sensitivity. LC/MS/MS results exhibited consistency in drug content on the stent surface. In-vitro release kinetic indicated the release of Sirolimus in 41 days from the date of implanted. Drug release was found at the first day, burst release was observed at 7th day of implantation. This study involved pharmacological coating of stents, based on the notion that sustained systemic local delivery of anti-proliferative agents. LC-MS/MS method has been successfully used in the pharmacokinetic analysis of Sirolimus coated drug eluting stents. Copyright © 2009 John Wiley & Sons, Ltd. [source] Optimization of dispersive liquid,liquid microextraction of Co(II) and Fe(III) as their oxinate chelates and analysis by HPLC: Application for the simultaneous determination of Co(II) and Fe(III) in water samplesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 23-24 2009Mir Ali Farajzadeh Abstract In this study, dispersive liquid,liquid microextraction method was used for the preconcentration and simultaneous determination of Co(II) and Fe(III) in water samples as their oxinate chelates. In dispersive liquid,liquid microextraction process, methanol and chloroform were used as disperser and extracting solvents, respectively, and the ligand 8-hydroxy quinoline was used as a chelating agent for the extraction of Co(II) and Fe(III). HPLC was applied for the quantitation of the analytes after preconcentration. An experimental design, central composite design, coupled with response surface methodology was used for the optimization of the involved experimental parameters. In addition, the effect of various experimental parameters in the extraction was investigated using one variable at a time method. The calibration graphs were linear in the range of 20,4000,,g/L with the LODs of 3,,g/L for both analytes. The RSDs for six replicate measurements of 500,,g/L of Co2+ and Fe3+ were 3.3 and 4.1%, respectively. [source] Enhanced solvent extraction of polar lipids associated with rubber particles from hevea brasiliensisPHYTOCHEMICAL ANALYSIS, Issue 2 2007Frederic Bonfils Abstract Biochemical studies of lipids bound to rubber particles have been complicated due to the solubility of polyisoprene chains in most extracting solvents and the rather delicate nature of polar lipids that are often denatured when traditional solvent extraction techniques are employed. In this paper, we describe a traditional technique and accompanying solvents that permit optimal extraction of rubber particle bound lipids. The technique, which is validated after characterizing the lipid extracts by elemental analysis, silica column adsorption and thin layer chromatography, appeared more suitable for extracting total lipids with optimal glycolipid and phospholipid contents. This technique is proposed as an alternative to traditional extraction methods used for solid natural rubber as it offers advantages with respect to ease of application, extract quality, extraction yields and reproducibility. Copyright © 2007 John Wiley & Sons, Ltd. [source] | |||||||||||||