Home About us Contact
|
Home About us Contact | ||
|
|
||
Analyte Recoveries (analyte + recovery)
Selected AbstractsA validated gas chromatographic method for the evaluation of enzymatic enantioselectivity in kinetic resolution applicationsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 6 2005Ykelien L. Boersma Abstract An enantioselective gas chromatography (GC) method has been developed and validated for determination of the enantiomers of citronellol in kinetic resolution experiments. S -(,)-,-Citronellol is a precursor of rose oxide. After solid-phase extraction (SPE) with ethyl acetate, the enantiomers of R -(+)-,-citronellol and S -(,)-,-citronellol and their corresponding acetate- and butyrate esters were separated through enantioselective GC respectively. The method was validated and found to be reproducible, specific, accurate, and precise. Analyte recoveries and detection limits were also determined. The applicability of this method was shown in a kinetic resolution experiment using lipase A of Bacillus subtilis. [source] Quantitative analyses of indoloquinazoline alkaloids in Fructus Evodiae by high-performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2006Yan Zhou Fructus Evodiae (Wuzhuyu), the fruits of Evodia rutaecarpa and related varieties, is widely used in traditional Chinese medicine. The bioactive constituents include the indoloquinazoline alkaloids rutaecarpine, evodiamine and dehydroevodiamine. A new assay based on high-performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry (HPLC/UV/APCI-MS/MS) was developed for the measurement of the indoloquinazoline alkaloids in commercial Fructus Evodiae products. Initially, the MS/MS fragmentation pathways of indoloquinazoline alkaloids were investigated to identify fragment ions that might be useful for the sensitive and selective detection of trace indoloquinazoline alkaloids during LC/MS/MS. Then, quantitative MS analysis of five indoloquinazoline alkaloids in 12 commercial Fructus Evodiae products from different geographical sources was performed. Analyte recovery was in the range of 97.5,105.3% for all with relative standard deviations (RSDs) below 6%, the intra-assay and inter-assay RSDs were less than 7%, and good linear relationships were shown with correlation coefficients for the analytes exceeding 0.999. Therefore, this LC/MS/MS assay facilitated the rapid quantitative analysis of rutaecarpine, evodiamine, evodiamide, 14-formyldihydrorutaecarpine and dehydroevodiamine in 12 commercial Fructus Evodiae products with excellent recovery, repeatability, accuracy and sensitivity. This method is simple and specific and can be used for identification and quality control of this traditional Chinese remedy. Copyright © 2006 John Wiley & Sons, Ltd. [source] Determination of flurbiprofen enantiomers in plasma using a single-isomer amino cyclodextrin derivative in nonaqueous capillary electrophoresis,ELECTROPHORESIS, Issue 17 2008Anne Rousseau Abstract A nonaqueous capillary electrophoresis (NACE) assay was developed for the separation and determination of flurbiprofen enantiomers in plasma samples using 6-monodeoxy-6-mono(3-hydroxy)propylamino-,-cyclodextrin as chiral selector. The nonaqueous background electrolyte was made up of 40,mM ammonium acetate in methanol (MeOH), and flufenamic acid was employed as internal standard. Solid-phase extraction was used for sample cleanup prior to the NACE separation. The NACE method reproducibility was optimized by evaluating different capillary washing sequences between runs. After having tested various conditions, trifluoroacetic acid (1,M) in MeOH was finally selected. Concerning the solid-phase extraction procedure, good and reproducible analyte recoveries were obtained using MeOH for protein denaturation and a polymeric phase combining hydrophobic interactions with anion exchange properties (Oasis® MAX) was selected as extraction sorbent. The method selectivity was not only demonstrated toward a blank plasma sample but also toward other non-steroidal anti-inflammatory drugs. The method was then successfully validated with respect to response function, trueness, precision, accuracy, linearity and limit of quantification. [source] Application of continual injection liquid-phase microextraction method coupled with liquid chromatography to the analysis of organophosphorus pesticidesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 4 2009Yanuardi Raharjo Abstract A liquid-phase microextraction coupled with LC method has been developed for the determination of organophosphorus pesticides (methidation, quinalphos and profenofos) in drinking water samples. In this method, a small amount (3 ,L) of isooctane as the acceptor phase was introduced continually to fill-up the channel of a 1.5 cm polypropylene hollow fiber using a microsyringe while the hollow fiber was immersed in an aqueous donor solution. A portion of the acceptor phase (ca. 0.4 ,L) was first introduced into the hollow fiber and additional amounts (ca. 0.2 ,L) of the acceptor phase were introduced to replenish at intervals of 3 min until set end of extraction (40 min). After extraction, the acceptor phase was withdrawn and transferred into a 2 mL vial for a drying step prior to injection into a LC system. Parameters that affect the extraction efficiency were studied including the organic solvent, length of fiber, volume of acceptor and donor phase, stirring rate, extraction time, and effect of salting out. The proposed method provided good enrichment factors of up to 189.50, with RSD ranging from 0.10 to 0.29%, analyte recoveries of over 79.80% and good linearity ranging from 10.0 to 1.25 mg/L. The LOD ranged from 2.86 to 82.66 ,g/L. This method was applied successfully to the determination of organophosphorus pesticides in selected drinking water samples. [source] Multiresidue determination of antibiotics in aquaculture fish samples by HPLC,MS/MSAQUACULTURE RESEARCH, Issue 9 2010Consuelo Cháfer-Pericás Abstract An analytical method based on HPLC with MS/MS detection was developed and optimized in order to determine the most useful antibiotics (sulphonamides and tetracyclines) used in aquaculture. A simple extraction procedure, without any clean-up step, was evaluated in order to obtain maximum analyte recovery from fish samples (Sparus aurata). A mixture of methanol:water 70:30 (v/v)+1 mL EDTA 0.1 M was selected as optimum extractant solution. Because no matrix effects were observed, a standard calibration curve prepared in mobile phase was used for quantification purposes. Antibiotic-free fish samples were spiked at different concentration levels and analysed by the optimized HPLC method. The average recoveries (n=6) obtained were satisfactory, ranging from 88% to 110% at 100 ,g kg,1. The proposed methodology provided limits of detection for the tested antibiotics in the 1.2,16 ,g kg,1 range, lower than 100 ,g kg,1, the maximum residue level established by the European Union. Finally, commercial fish samples from different origins were analysed in order to confirm the usefulness of the developed methodology. [source] | ||||||||||