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mmol/L Ammonium Acetate (l + ammonium_acetate)
Selected AbstractsDetermination of glycyrrhetic acid in human plasma by HPLC-MS method and investigation of its pharmacokineticsJOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 3 2008W.-J. Zhao PhD Summary Objective:, To develop a high performance liquid chromatography mass spectrometry (HPLC-MS) method for the determination of the glycyrrhetic acid (GA) in human plasma and for the investigation of its pharmacokinetics after the oral administration of 150 mg diammonium glycyrrhizinate test and reference capsule formulations. Methods:, The GA in plasma was extracted with ethyl acetate, separated on a C18 column with a mobile phase of methanol (5 mmol/L ammonium acetate),water (85 : 15, V/V) and analysed using a MS detector. Ursolic acid (UA) was used as internal standard. The target ions were m/z 469·5 for GA and m/z 455·6 for UA, the fragment voltages were 200 V and 100 V for GA and UA respectively. Results:, The calibration curve was linear over the range of 0·5,200 ng/mL (r = 0·9974). The limit of quantification for GA in plasma was 0·5 ng/mL, the recovery was 76·0,80·0%, and the inter- and intra-day relative standard deviations (RSD) were <12%. The pharmacokinetic parameters of GA after a single dose of 150 mg diammonium glycyrrhizinate test and reference were as follows: the half life (t1/2) 9·65 ± 3·54 h and 9·46 ± 2·85 h, the time to peak concentration (Tmax) 10·95 ± 1·32 h and 11·00 ± 1·30 h, the peak concentration (Cmax) 95·57 ± 43·06 ng/mL and 103·89 ± 49·24 ng/mL; the area under time-concentration curve (AUC0,48 and AUC0,,) 1281·84 ± 527·11 ng·h/mL and 1367·74 ± 563·27 ng·h/mL, 1314·32 ± 566·40 ng·h/mL and 1396·97 ± 630·06 ng·h/mL. The relative bioavailability of diammonium glycyrrhizinate capsule was 98·88 ± 12·98%. Conclusion:, The assay was sensitive, accurate and convenient, and can be used for the determination of GA in human plasma. Comparison of the bioavailability and pharmacokinetic profile of GA indicated that the test and reference capsules were bioequivalent. [source] A sensitive liquid chromatography,electrospray ionization,mass spectrometry method for the simultaneous determination of pentoxyverine citrate and guaifenesin in human plasma,application to pharmacokinetic and bioequivalence studiesBIOMEDICAL CHROMATOGRAPHY, Issue 4 2010Jinhua Wen Abstract A sensitive and specific liquid chromatography,electrospray ionization,mass spectrometry method for the identification and quantification of pentoxyverine citrate and guaifenesin in human plasma has been developed. After extraction from plasma samples by ethyl acetate, the internal standard and analytes were separated by high-performance liquid chromatographic on a Shim-pack VP-ODS C18 column (150 × 2.0 mm) using a mobile phase consisting of A (methanol) and B (0.4% glacial acetic acid and 4 mmol/L ammonium acetate) (A:B, 43 : 57). Analysis was performed on a Shimadzu LC/MS-2010A in selected ion monitoring mode with a positive electrospray ionization interface. The method was linear in the concentration range of 1.0,640.0 ng/mL for pentoxyverine citrate and 0.025,6.4 ,g/mL for guaifenesin. The inter- and intra- precision were all within 12% and accuracy ranged from 85 to 115%. The lower limits of quantification were 1.0 ng/mL for pentoxyverine citrate and 25.0 ng/mL for guaifenesin. The extraction recovery was on average 81.95% for pentoxyverine citrate and 89.03% for guaifenesin. This is the first assay method reported for the simultaneous determination of pentoxyverine citrate and guaifenesin in plasma using one chromatographic run. Copyright © 2009 John Wiley & Sons, Ltd. [source] Measurement of fexofenadine concentration in micro-sample human plasma by a rapid and sensitive LC-MS/MS employing protein precipitation: application to a clinical pharmacokinetic studyBIOMEDICAL CHROMATOGRAPHY, Issue 3 2010Daqing Guo Abstract A simple, rapid and sensitive liquid chromatography/positive ion electro-spray tandem mass spectrometry method (LC-MS/MS) was developed and validated for the quantification of fexofenadine with 100,,L human plasma employing glipizide as internal standard (IS). Protein precipitation was used in the sample preparation procedure. Chromatographic separation was achieved on a reversed-phase C18 column (5,,m, 100 × 2.1,mm) with methanol,:,buffer (containing 10,mmol/L ammonium acetate and 0.1% formic acid; 70,:,30, v/v) as mobile phase. The total chromatographic runtime was approximately 3.0,min with retention time for fexofenadine and IS at approximately 1.9 and 2.1,min, respectively. Detection of fexofenadine and IS was achieved by LC-MS/MS in positive ion mode using 502.1 , 466.2 and 446.0 , 321.1 transitions, respectively. The method was proved to be accurate and precise at linearity range of 1,600,ng/mL with a correlation coefficient (r) of ,0.9976. The validated method was applied to a pharmacokinetic study in human volunteers following oral administration of 60 or 120,mg fexofenadine formulations, successfully. Copyright © 2009 John Wiley & Sons, Ltd. [source] Chiral Separation of Calcium (,)-2(S)-2-Benzyl-4-oxo-4-(cis -hexahydro-2-isoindolinyl)butyrate Enantiomers by High-performance Liquid Chromatography,CHINESE JOURNAL OF CHEMISTRY, Issue 1 2009Zhefeng ZHANG Abstract A chiral high-performance liquid chromatographic method was developed for the enantioseparation of a new insulinotropic drug of the glinide class with rapid onset. The chiral separation was performed on a Sumichiral OA-3300 column (250 mm×4.6 mm, 5 µm) with methanol containing 0.05 mol/L ammonium acetate as the optimized mobile phase at detection wavelengh 210 nm. Baseline separation of the two enantiomers was obtained in 22 min with a resolution of 3.01. Calibration graphs were constructed in a range of 0.028,5.6 µg·mL,1 for S - and 0.03,6.0 µg·mL,1 for R -(,)-enantiomer, respectively. The linear correlation equations are: y=1.32×103x,2.54 (r=0.9997) for S -enantiomer and y=1.15×103x,1.78 (r=0.9998) for R -enantiomer, respectively. The limits of detection obtained by S/N=3 were 0.15 ng for S - and 0.10 ng for R -enantiomer, respectively. RSD of the method was below 1.0% (n=5). [source] | ||||||||||