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Isocratic Mobile Phase Consisting (isocratic + mobile_phase_consisting)
Selected AbstractsIdentification of dimer impurities in ampicillin and amoxicillin by capillary LC and tandem mass spectrometryJOURNAL OF SEPARATION SCIENCE, JSS, Issue 3 2007Chi-Yu Lu Abstract A micro-scale liquid chromatography electrospray ionization tandem mass spectrometric method was developed for the identification of polymerized impurities in ampicillin and amoxicillin in aqueous solution. Ampicillin and amoxicillin are broad-spectrum antibiotics and widely used for the treatment of human and animal infections. In this study ampicillin, amoxicillin, and their dimers were trapped in a 5-cm capillary column containing C18 sorbents. The analytes were separated on a reversed-phase column and introduced into the mass spectrometer via a nanospray ion source. An isocratic mobile phase consisting of 1% formic acid-acetonitrile (50 : 50, v/v) was used. For identification, the fragment ions of the analytes were monitored. The aim of the present study was to develop an optimized quality control method for the analysis of high molecular weight impurities of ampicillin and amoxicillin. [source] Simultaneous quantification of CTN986 and its deglycosylation products in rat serum using liquid chromatography/tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2006Jifen Guo A quantitative method for the simultaneous determination of CTN986, a flavonol triglycoside, and its two deglycosylation products rutin and hirsutin in rat serum was developed and validated for the investigation of the pharmacokinetics of CTN986. Analytes were isolated from the serum samples (200,µL) prior to analysis by liquid chromatography/tandem mass spectrometry (LC/MS/MS) using C18 solid-phase extraction, and were separated on a Zorbax C8 reversed-phase column with an isocratic mobile phase consisting of methanol/isopropanol/water/formic acid (20:10:70:0.1, v/v/v/v). The protonated analytes generated in the positive ion mode were monitored through multiple reaction monitoring in an eletrospray ionization source. Calibration was performed by internal standardization with CTN987, a flavonoid structurally similar to CTN986, and regression curves were constructed ranging from 2 to 1000,ng/mL in 200,µL serum samples. The intra- and inter-day precision values were below 11% and accuracy was between ,2.37 and 1.4% for all quality control samples. This quantitation method was successfully applied to pharmacokinetic studies of CTN986 in rats following oral and intravenous administration. Rutin and hirsutin were not detected in rat serum. Copyright © 2006 John Wiley & Sons, Ltd. [source] Liquid chromatographic,tandem mass spectrometry assay for quantitation of a novel antidiabetic S002-853 in rat plasma and its application to pharmacokinetic study,BIOMEDICAL CHROMATOGRAPHY, Issue 7 2010N. Gautam Abstract A sensitive and selective LC-MS/MS method has been developed and validated for the estimation of novel antidiabetic synthetic flavonoid S002-853 in rat plasma using centchroman as an internal standard. The method involves a simple two-step liquid,liquid extraction with diethyl ether. The analyte was chromatographed on a Pierce Spheri-5, guard cyano column (30 × 4.6,,mm i.d., 5,,µm) with isocratic mobile phase consisting of methanol,ammonium acetate buffer (pH 4.6, 10,,mm; 90,:,10, v/v) at a flow rate of 0.75,,mL/min. The API 4000 triple-quadrupole LC,MS/MS system was operated under multiple reaction-monitoring mode. The ionization was performed by electrospray ionization technique in positive ion mode. The chromatographic run time was 6,,min and the weighted (1/x2) calibration curves were linear over the range 0.78,400,,ng/mL. The limit of detection and lower limit of quantification were 0.195 and 0.78,,ng/mL, respectively. The intra- and inter-batch accuracy (%bias) and precision (%RSD) were found to be less than 8.47 and 11.6% respectively. The average absolute recoveries of S002-853 and internal standard from spiked plasma samples were >90%. S002-853 was stable for 8,,h at ambient temperature, 4 weeks at ,60°C and after three freeze,thaw cycles. The assay was successfully applied to determine the pharmacokinetic parameters in male Sprague,Dawley rats after an oral dose administration at 25,,mg/kg. Copyright © 2009 John Wiley & Sons, Ltd. [source] Development of a novel HPLC-MS/MS method for the determination of aconitine and its application to in vitro and rat microdialysis samplesBIOMEDICAL CHROMATOGRAPHY, Issue 7 2009Quan-long Zhang Abstract A sensitive and selective LC-MS/MS method was developed and validated for the determination of aconitine in microdialysate and rat plasma. Extraction of plasma sample was conducted by use of 1% trichloracetic acid and acetonitrile solution with 10 ng/mL internal standard (propafenone) spiked. Microdialysates were analyzed without sample purification. After sample preparation, 2 µL were injected and separated with an isocratic mobile phase consisting of acetonitrile:0.1% formic acid (60:40, v/v) at a flow rate of 0.3 mL/min. The Agilent G6410A triple quadrupole LC/MS system was operated under the multiple-reaction monitoring mode (MRM) using the electrospray ionization technique in positive mode. Overall, the assay exhibited good precision and accuracy. The diffusion properties of aconitine investigated in in vitro microdialysis experiments revealed unfavourable concentration dependence avertable by keeping a constant pH 5.77 using isotonic phosphate buffer solution as perfusate. The mean relative recoveries were 48.23% [coefficient of variation (CV 4.47%)] and 55.38% (CV 2.89%) for retrodialysis and recovery experiments, respectively. The in vivo recovery of aconitine was 34.48% (CV 3.05%) and was stable over the 6 h study period. Following characterization of aconitine both in vitro and in vivo microdialysis, the developed setting is suitable for application in pharmacokinetics and pharmacodynamics studies. Copyright © 2009 John Wiley & Sons, Ltd. [source] Simultaneous determination of udenafil and its active metabolite, DA-8164, in human plasma and urine using ultra-performance liquid chromatography,tandem mass spectrometry: application to a pharmacokinetic studyBIOMEDICAL CHROMATOGRAPHY, Issue 9 2008Soo Kyung Bae Abstract A rapid, sensitive, and simple ultra-performance liquid chromatography,tandem mass spectrometry (UPLC/MS/MS) method for the determination of udenafil and its active metabolite, DA-8164, in human plasma and urine using sildenafil as an internal standard (IS) was developed and validated. Udenafil, DA-8164 and IS from a 100 µL aliquot of biological samples were extracted by protein precipitation using acetonitrile. Chromatographic separation was carried on an Acquity UPLC BEH C18 column (50 × 2.1 mm, i.d., 1.7 µm) with an isocratic mobile phase consisting of acetonitrile and containing 0.1% formic acid (75:25, v/v) at flow rate of 0.4 mL/min, and total run time was within 1 min. Detection and quantification was performed by the mass spectrometer using multiple reaction-monitoring mode at m/z 517 , 283 for udenafil, m/z 406 , 364 for DA-8164 and m/z 475 , 100 for IS. The assay was linear over a concentration range of 1,600 ng/mL with a lower limit of quantification of 1 ng/mL in both human plasma and urine. The coefficient of variation of this assay precision was less than 13.7%, and the accuracy exceeded 92.0%. This method was successfully applied for pharmacokinetic study after oral administration of udenafil 100 mg to healthy Korean male volunteers. Copyright © 2008 John Wiley & Sons, Ltd. [source] Determination of Tetracyclines in Honey Using Liquid Chromatography with Ultraviolet Absorbance Detection and Residue Confirmation by Mass SpectrometryCHINESE JOURNAL OF CHEMISTRY, Issue 9 2007Yan Liu Abstract A determination method has been optimized and validated for the simultaneous analysis of tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC) and doxycycline (DC) in honey. Tetracyclines (TCs) were removed from honey samples by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns and eluted with Na2EDTA-Mcllvaine pH 4.0 buffers. Extracts were further cleaned up by Oasis HLB solid-phase extraction (SPE), while other solid-phase extraction cartridges were compared. Chromatographic separation was achieved using a polar end-capped C18 column with an isocratic mobile phase consisting of oxalic acid, acetonitrile, and methanol. LC with ultraviolet absorbance at 355 nm resulted in the quantitation of all four tetracycline residues from honey samples fortified at 15, 50, and 100 ng/g, with liner ranges for tetracyclines of 0.05 to 2 µg/mL. Mean recoveries for tetracyclines were greater than 50% with R.S.D. values less than 10% (n=18). Detection limits of 5, 5, 10, 10 ng/g for oxytetracycline, tetracycline, chlortetracycline and doxycycline, respectively and quantitation limits of 15 ng/g for all the four tetracyclines were determined. Direct confirmation of the four residues in honey(2,50 ng/g) was realized by liquid chromatography-tandem mass spectrometry (LC/MS/MS). The linear ranges of tetracyclines determined by LC/MS/MS were between 5 to 300 ng/mL, with the linear correlation coefficient r>0.995. The limits of detection of 1 to 2 ng/g were obtained for the analysis of the TCs in honey. [source] | ||||||||||