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Oasis HLB Cartridge (oasis + hlb_cartridge)
Selected AbstractsSimultaneous determination of maraviroc and raltegravir in human plasma by HPLC-UVIUBMB LIFE, Issue 4 2009Stefania Notari Abstract Therapeutic drug monitoring is pivotal to improve the management of HIV infection. Here, a new HPLC,UV method to quantify simultaneously maraviroc and raltegravir levels in human plasma is reported. Remarkably, this is the first method for maraviroc determination in human plasma. The volume of the plasma sample was 600 ,L. This method involved automated solid-phase extraction with Oasis HLB Cartridge 1 cc (30 mg divinylbenzene and N -vinylpyrrolidone) and evaporation in a water bath under nitrogen stream. The extracted samples were reconstituted with 200 ,L 50/50 of mobile-phase solution (0.01 M KH2PO4 and acetonitrile). Twenty microliters of these samples were injected into a HPLC,UV system, the analytes were eluted on an analytical dC18 Atlantis column (150 mm × 4.6 mm I.D.) with a particle size of 5 ,m. The mobile phase (0.01 M KH2PO4 and acetonitrile) was delivered at 1.0 mL/min with isocratic elution. The total run time for a single analysis was 10 min; maraviroc and raltegravir were detected by UV at 197 and 300 nm. The calibration curves were linear up to 2,500 ng/mL. The absolute recovery ranged between 93 and 100%. The HPLC,UV method reported here has been validated and is currently applied to monitor plasma levels of maraviroc and raltegravir in HIV-infected patients. © 2009 IUBMB IUBMB Life, 61(4):470,475, 2009 [source] Determination of fluoroquinolone antibiotics in surface waters from Mondego River by high performance liquid chromatography using a monolithic columnJOURNAL OF SEPARATION SCIENCE, JSS, Issue 17 2007Angelina Pena Abstract A novel LC,fluorescence detection method based on the use of a monolithic column for the determination of norfloxacin, ciprofloxacin, and enrofloxacin antibiotic residues in environmental waters was developed. Fluoroquinolones (FQs) were isocratically eluted using a mobile phase consisting of 0.025 M phosphoric acid solution at pH 3.0 with tetrabutylammonium and methanol (960:40, v/v) through a Chromolith Performance RP-18e column (100×4.6 mm) at a flow rate of 2.5 mL/min and detected at excitation and emission wavelengths of 278 and 450 nm, respectively. After acidification and addition of EDTA, water samples were extracted using an Oasis HLB cartridge. Linearity was evaluated in the range of 0.05 to 1 ,g/mL and correlation coefficients of 0.9945 for norfloxacin, 0.9974 for ciprofloxacin, and 0.9982 for enrofloxacin were found. The limit of quantification was 25 ng/L for the three FQs. The recovery of FQs spiked into river water samples at 25, 50, and 100 ng/L fortification levels ranged from 76.5 to 91.0% for norfloxacin, 78.5 to 97.2% for ciprofloxacin, and 79.4 to 93.6% for enrofloxacin. This method was successfully applied to the analysis of water samples from the Mondego River, and ciprofloxacin and enrofloxacin residues were detected in eight water samples. [source] High-performance liquid chromatography with solid-phase extraction for the quantitative determination of nilotinib in human plasmaBIOMEDICAL CHROMATOGRAPHY, Issue 7 2010Masatomo Miura Abstract A simple, rapid and sensitive high-performance liquid chromatography (HPLC)-based method with ultraviolet detection was developed for the quantitation of nilotinib, a tyrosine kinase inhibitor, in human plasma. Nilotinib and the internal standard dasatinib were separated using a mobile phase of 0.5% KH2PO4 (pH2.5),acetonitrile,methanol (55:25:20, v/v/v) on a Capcell Pak MG II column (250 × 4.6,mm) at a flow rate of 0.5,mL/min and optical measurement at 250,nm. Analysis required only 100,,L of plasma and involved a rapid and simple solid-phase extraction with an Oasis HLB cartridge, which gave recoveries from 72 to 78% for nilotinib and from 74 to 76% for dasatinib. The lower limit of quantification for nilotinib was 10,ng/mL. The linear range of this assay was between 10 and 5000,ng/mL (r2 > 0.9992 for the regression line). Intra- and inter-day coefficients of variation were less than 10.0% and accuracies were within 10.4% over the linear range. Our results indicate that this method is applicable to the monitoring of plasma levels of nilotinib in a clinical setting. Copyright © 2009 John Wiley & Sons, Ltd. [source] Determination of cholesterol in human hair using gas chromatography,mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 10 2006Hye Kyung Ryu Abstract This work describes a sensitive method for determining cholesterol in human hair using GC-MS. In this study, we used a very small amount of hair, only 1 mg, to quantify cholesterol. We also can achieve more effective purification and a good recovery over 92% with solid-phase extraction using an Oasis HLB cartridge. The intra-day and inter-day precision and accuracy values were less than 7.08%. Cholesterol was determined to be in the range of 355,1693 µg/g in healthy human hair. We tested the concentration correlation between the serum and hair to examine the feasibility of using the hair cholesterol level as an index of the serum cholesterol level. The correlation between the serum cholesterol was 0.86 (r -value) in patients with hypercholesterolemia. This finding indicates that, in the clinical field, hair could replace serum in cholesterol level measurement. Copyright © 2006 John Wiley & Sons, Ltd. [source] Development and validation of a liquid chromatographic/electrospray ionization mass spectrometric method for the quantitation of prazepam and its main metabolites in human plasmaJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2005Paraskevi Valavani Abstract A method was developed and fully validated for the quantitation of prazepam and its major metabolites, oxazepam and nordiazepam, in human plasma. Sample pretreatment was achieved by solid-phase extraction using Oasis HLB cartridges. The extracts were analysed by high-performance liquid chromatography (HPLC) coupled with single-quadrupole mass spectrometry (MS) with an electrospray ionization interface. The MS system was operated in the selected ion monitoring mode. HPLC was performed isocratically on a reversed-phase XTerra MS C18 analytical column (150 × 3.0 mm i.d., particle size 5 µm). Diazepam was used as the internal standard for quantitation. The assay was linear over a concentration range of 5.0,1000 ng ml,1 for all compounds analyzed. The limit of quantitation was 5 ng ml,1 for all compounds. Quality control samples (5, 10, 300 and 1000 ng ml,1) in five replicates from three different runs of analysis demonstrated an intra-assay precision (CV) of ,9.1%, an inter-assay precision of ,6.0% and an overall accuracy (relative error) of <4.6%. The method can be used to quantify prazepam and its metabolites in human plasma covering a variety of pharmacokinetic or bioequivalence studies. Copyright © 2005 John Wiley & Sons, Ltd. [source] A rapid ultra-performance liquid chromatography,electrospray Ionisation mass spectrometric method for the analysis of saponins in the adventitious roots of Panax notoginsengPHYTOCHEMICAL ANALYSIS, Issue 1 2009Mo Dan Abstract Introduction Saponins are bioactive compounds employed in the prevention and treatment of cardiovascular and cerebrovascular diseases. The adventitious roots of Panax notoginseng may offer an alternative source of saponins. Identification and determination of saponins in the crude extract is challenging owing to their similar structures and the lack of standards. Objective To develop a rapid, sensitive and accurate method based on solid-phase extraction followed by ultra-performance liquid chromatography,electrospray ionisation mass spectrometry (UPLC-ESI-MS) for the identification and quantification of saponins in P. notoginseng. Methodology Following extraction using Waters OasisTM HLB cartridges, the analytes were subjected to a UPLC system with a Waters Acquity BEH C18 chromatographic column and a binary mobile phase system consisting of 0.05% formic acid in water and acetonitrile under gradient elution conditions, with final detection by ESI-MS in the positive ion mode. Results The UPLC-ESI-MS method gave limits of detection and quantification within the range 0.015,0.382 and 0.052,1.124 µg/mL, respectively, for 15 studied saponins. The instrumentation/injection precision (RSD) was 4.5% for a low concentration and 3.2% for an intermediate concentration sample. The intra- and inter-day repeatability was less than 2.65% (RSD). The method described was validated using spiked samples with different amounts of saponin standards. Conclusion This UPLC-ESI-MS assay provides a suitable quality control method for the tentative identification and determination of major biological active constituents in adventitious and native roots of P. notoginseng. Copyright © 2008 John Wiley & Sons, Ltd. [source] Enantioselective HPLC-UV method for determination of eslicarbazepine acetate (BIA 2-093) and its metabolites in human plasmaBIOMEDICAL CHROMATOGRAPHY, Issue 11 2007Gilberto Alves Abstract Eslicarbazepine acetate (BIA 2-093) is a novel central nervous system drug undergoing clinical phase III trials for epilepsy and phase II trials for bipolar disorder. A simple and reliable chiral reversed-phase HPLC-UV method was developed and validated for the simultaneous determination of eslicarbazepine acetate, oxcarbazepine, S- licarbazepine and R -licarbazepine in human plasma. The analytes and internal standard were extracted from plasma by a solid-phase extraction using Waters Oasis® HLB cartridges. Chromatographic separation was achieved by isocratic elution with water,methanol (88:12, v/v), at a flow rate of 0.7 mL/min, on a LichroCART 250-4 ChiraDex (, -cyclodextrin, 5 µm) column at 30°C. All compounds were detected at 225 nm. Calibration curves were linear over the range 0.4,8 µg/mL for eslicarbazepine acetate and oxcarbazepine, and 0.4,80 µg/mL for each licarbazepine enantiomer. The overall intra- and interday precision and accuracy did not exceed 15%. Mean relative recoveries varied from 94.00 to 102.23% and the limit of quantification of the assay was 0.4 µg/mL for all compounds. This method seems to be a useful tool for clinical research and therapeutic drug monitoring of eslicarbazepine acetate and its metabolites S- licarbazepine, R -licarbazepine and oxcarbazepine. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||