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Separation Resolution (separation + resolution)
Selected AbstractsAnalyses of alkaloids in different products by NACE-MSELECTROPHORESIS, Issue 22 2007Chen-Wen Chiu Abstract A simple method for the separation and characterization of five nicotine-related alkaloids by NACE employing UV and MS detections is described here for the first time. Several factors, including NACE parameters (compositions of running solution) and MS parameters (such as nature and flow rate of sheath liquid, pressure of nebulization gas, and flow rate of dry gas), were optimized in order to obtain both an adequate CE separation and high MS signals for the alkaloid compounds used in this study. A reliable CE separation of five alkaloids was achieved in 50,mM ammonium formate that was dissolved in an ACN/methanol mixture (50:50, v/v) of pH*,4.0 (apparent pH 4.0). The optimal electrospray MS measurement was carried out in the positive ionization mode using a coaxial sheath liquid composed of isopropyl alcohol and water in the ratio of 80:20 v/v at a flow rate of 180,,L/h. In addition, the proposed NACE method was also applied in the analyses of alkaloids in several products including chewing gums, beverages, and tobaccos. This NACE-MS method was found to provide a better detection ability and separation resolution for the analysis of nicotine alkaloids when compared to other aqueous CE-MS reports. [source] Application of Hadamard transformation to MEKCELECTROPHORESIS, Issue 3 2007Kazuki Hata Abstract The Hadamard transform (HT) technique, which permits the S/N in CE to be improved, was applied to MEKC. Multiple sample injection of fluorescent analytes according to a Hadamard code sequence was performed using an optically gated sample injection technique, in which a sample plug was produced based on photodegradation by irradiation with an intense laser beam. The capillary and reservoirs were filled with a sample solution containing buffer components and SDS as a pseudostationary phase. A preliminary study confirmed that fluorescein ion could be photobleached in the presence of SDS. The optically gated sample injection technique was then applied to multiple sample injection, based on a Hadamard matrix. The S/N in the electropherogram obtained by HT-MEKC was improved substantially compared to that obtained by a single injection method. When the technique was applied to the separation of several amino acids labeled with FITC, the S/N ratio for each amino acid was enhanced, without any evidence of degradation in separation resolution. Moreover, HT-MEKC was applied to the analysis of amino acids contained in a Japanese beverage, resulting in improved S/Ns for the amino acids. [source] Analyses of preservatives by capillary electrochromatography using methacrylate ester-based monolithic columnsELECTROPHORESIS, Issue 18-19 2004Hsi-Ya Huang Abstract Five common food preservatives were analyzed by capillary electrochromatography, utilizing a methacrylate ester-based monolithic capillary as separation column. In order to optimize the separation of these preservatives, the effects of the pore size of the polymeric stationary phase, the pH and composition of the mobile phase on separation were examined. For all analytes, it was found that an increase in pore size caused a reduction in retention time. However, separation performances were greatly improved in monolithic columns with smaller pore sizes. The pH of the mobile phase had little influence on separation resolution, but a dramatic effect on the amount of sample that was needed to be electrokinetically injected into the monolithic column. In addition, the retention behaviors of these analytes were strongly influenced by the level of acetonitrile in the mobile phase. An optimal separation of the five preservatives was obtained within 7.0 min with a pH 3.0 mobile phase composed of phosphate buffer and acetonitrile 35:65 v/v. Finally, preservatives in real commercial products, including cold syrup, lotion, wine, and soy sauces, were successfully determined by the methacrylate ester-based polymeric monolithic column under this optimized condition. [source] On-line concentration and pressurized capillary electrochromatographic analysis of phytohormones in cornJOURNAL OF SEPARATION SCIENCE, JSS, Issue 5 2008Shujuan Wang Abstract A pressurized CEC (pCEC) method was developed for the separation of phytohormones, in which UV absorbance was used as the detector and a monolithic silica-ODS column as the separation column. The parameters (including the concentration of organic solvent in the mobile phase, pH of the electrolyte buffer, applied voltage) affecting the separation resolution were evaluated. Two on-line concentration techniques, namely, solvent gradient zone sharpening effect and field-enhanced sample stacking, were utilized to improve detection sensitivity. The combination of the two techniques proved to be beneficial to enhance the detection sensitivity by enabling the injection of large volumes of samples. Compared to the conventional injection mode, the enhancement in the detection sensitivities of phytohormones using the on-line concentration technique is in the range from 9- to 23-fold. The developed pCEC method was applied to evaluate phytohormones in corns. [source] Microfabricated Polymer Chip for Capillary Gel ElectrophoresisBIOTECHNOLOGY PROGRESS, Issue 5 2001Jong Wook Hong A polymer (PDMS: poly(dimethylsiloxane)) microchip for capillary gel electrophoresis that can separate different sizes of DNA molecules in a small experimental scale is presented. This microchip can be easily produced by a simple PDMS molding method against a microfabricated master without the use of elaborate bonding processes. This PDMS microchip could be used as a single use device unlike conventional microchips made of glass, quartz or silicon. The capillary channel on the chip was partially filled with agarose gel that can enhance separation resolution of different sizes of DNA molecules and can shorten the channel length required for the separation of the sample compared to capillary electrophoresis in free-flow or polymer solution format. We discuss the optimal conditions for the gel preparation that could be used in the microchannel. DNA molecules were successfully driven by an electric field and separated to form bands in the range of 100 bp to 1 kbp in a 2.0% agarose-filled microchannel with 8 mm of effective separation length. [source] | ||||||||||