|
| ||
|
|
||
CZE Methods (cze + methods)
Selected AbstractsDetermination of tobacco-specific N -nitrosamines in rabbit serum by capillary zone electrophoresis and capillary electrophoresis-electrospray ionization-mass spectrometry with solid-phase extractionELECTROPHORESIS, Issue 11 2006Chenchen Li Abstract In this paper, we propose a new strategy for separation and determination of tobacco-specific N -nitrosamines (TSNAs), a group of strong carcinogens found only in tobacco products, by using CZE and CE-MS associated with SPE. Six TSNAs: N'-nitrosonornicotine, N'-nitrosoanatabine, N'-nitrosoanabasine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, and 4-(methylnitrosamino)-4-(3-pyridyl)-1-butanol were simultaneously separated by either of two CZE methods, one of which worked with ammonium formate buffer (pH,2.5) and another with citrate buffer (pH,2.4), as well as a CE-MS method. The CZE conditions including pH and concentration of running buffer, capillary length, applied voltage, and capillary temperature were systematically optimized. For CE-MS method, an optimized sheath liquid consisted of methanol,water was used at a flow rate of 10,,L/min. With SPE procedure, our proposed CE-MS method was successfully applied to determine TSNAs after 15,min metabolism in rabbits. A comparison study between CZE and CE-MS methods for quantitative purposes was carried out, showing that both methods provided similar separation efficiency, selectivity, repeatability, linearity, and recovery. However, CE-MS method was better suited for the analysis of TSNAs in complicated biological samples for its sensitivity and extra information on molecular structure. Having good accordance with our previous work by using LC-MS, the new CE-MS method is expected to be an alternative to the LC-MS method and applied to study the metabolism of TSNAs. [source] Comparison of HPLC and CZE methods for analysis of DOTA-like esters , reaction intermediates in synthesis of magnetic resonance contrast agentsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 4-5 2010Anna Hamplová Abstract RP-HPLC and non-aqueous CZE methods were evaluated for qualitative and quantitative analysis of esterified macrocyclic compounds of the DOTA family (DOTA=1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid). This group of compounds represents important reaction intermediates in synthesis of magnetic resonance contrast agents. Calibration curves in the concentration range from 1.0×10,5 to 1.0×10,3,mol/L were plotted and the experimental data were critically compared in terms of their repeatability, linearity, LOD and LOQ. The optimized methods were successfully applied to the analysis of a real reaction mixture without any further pretreatment. [source] Use of capillary electrophoresis in drug quality assessment of synthetic porcine secretinBIOMEDICAL CHROMATOGRAPHY, Issue 1 2005Baile A. Moumakwa Abstract The purity pro,le for porcine secretin attributable to contamination by equilibrium products such as aspartoyl3 secretin has been shown to be dependent on the pH of the analytical system. Capillary zone electrophoresis (CZE) methods have been developed for the ef,cient separation of synthetic porcine secretin, its equilibrium products and other impurities in aqueous solutions at both acidic and alkaline pH. These conditions are more representative of those used for the reconstitution and administration of porcine secretin, and good results cannot be achieved using HPLC due to poor peak shape above pH 5.8. The in,uence of various CZE operational parameters was systematically examined. The methods were validated for accuracy, precision, linearity, LOD and LOQ. A comparative evaluation of the stability of test solutions was determined using CZE and HPLC over a range of pH values. HPLC and CZE methods produced similar results at low pH. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||