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Separation Parameters (separation + parameter)
Selected AbstractsRapid analysis of constituents of Radix Cyathulae using hydrophilic interaction-reverse phase LC-MSJOURNAL OF SEPARATION SCIENCE, JSS, Issue 22 2009Mei-Ting Ren Abstract A hydrophilic interaction chromatography (HILIC) and reverse-phase liquid chromatography (RPLC) coupled with electrospray TOF MS method was developed for the analysis and characterization of constituents in the radix of Cyathula officinalis Kuan. Separation parameters of HILIC such as buffer pH, mobile phase strength, and organic modifier were evaluated. Fructose, glucose, and sucrose were identified by HILIC-ESI/TOF MS. Reverse-phase liquid chromatography-ESI/TOF MS were applied for quick and sensitive identification of major saponins in Cyathula officinalis. In-source collision-induced dissociation has been performed to elucidate the fragmentation pathways of oleanane-, hederagenin-, and gypsogmin-type saponins. Twelve saponins were characterized in this plant for the first time, and four of them were presumed to be new compounds. In addition, one phytoecdysteroid (cyasterone) and one coumarin (6,7-dimethoxycoumarin) were detected at the same time. The present method was capable of rapid characterizing and providing structure information of constituents from herbal drugs. [source] Absolute enantioselective separation: Optical activity ex machinaJOURNAL OF SEPARATION SCIENCE, JSS, Issue 17 2005Roman Bielski Abstract The paper describes methodology of using three independent macroscopic factors affecting molecular orientation to accomplish separation of a racemic mixture without the presence of any other chiral compounds, i. e., absolute enantioselective separation (AES) which is an extension of a concept of applying these factors to absolute asymmetric synthesis. The three factors may be applied simultaneously or, if their effects can be retained, consecutively. The resulting three mutually orthogonal or near orthogonal directors constitute a true chiral influence and their scalar triple product is the measure of the chirality of the system. AES can be executed in a chromatography-like microfluidic process in the presence of an electric field. It may be carried out on a chemically modified flat surface, a monolithic polymer column made of a mesoporous material, each having imparted directional properties. Separation parameters were estimated for these media and possible implications for the natural homochirality are discussed. [source] Analytical potential of 6-oxy-(N -succinimidyl acetate)-9-(2'-methoxycarbonyl) fluorescein for the determination of amino compounds by capillary electrophoresis with laser-induced fluorescence detectionELECTROPHORESIS, Issue 10 2005Liwei Cao Abstract The analytical potential of a fluorescein analogue, 6-oxy-(N -succinimidyl acetate)-9-(2'-methoxycarbonyl) fluorescein (SAMF), for the first time synthesized in our laboratory, as a labeling reagent for the labeling and determination of amino compounds by capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection was investigated. Biogenic monoamines and amino acids were chosen as model analytes to evaluate the analytical possibilities of this approach. The derivatization conditions and separation parameters for the biogenic amines were optimized in detail. The derivatization was performed at 30°C for 6 min in boric acid buffer (pH 8.0). The derivatives were baseline-separated in 15 min with 25 mM boric acid running buffer (pH 9.0), containing 24 mM SDS and 12.5% v/v acetonitrile. The concentration detection limit for biogenic amines reaches 8×10,11 mol·L,1 (signal-to-noise ratio = 3). The application of CE in the analysis of the SAMF-derivatized amino acids was also exploited. The optimal running buffer for amino acids suggested that weak acidic background electrolyte offered better separation than the basic one. The proposed method was applied to the determination of biogenic amines in three different beer samples with satisfying recoveries varying from 92.8% to 104.8%. Finally, comparison of several fluorescein-based probes for amino compounds was discussed. With good labeling reaction, excellent photostability, pH-independent fluorescence (pH 4,9), and the resultant widely suited running buffer pH, SAMF has a great prospect in the determination of amino compounds in CE. [source] Supercritical CO2 extraction of accumulated capsidiol from biotic elicitor-activated Capsicum annuum L fruit tissuesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2005ur Salg Abstract This work investigates the supercritical CO2 extraction of capsidiol from pepper fruit tissues activated with Alternaria alternate (Fr) Keissler suspension culture as a biotic elicitor. Capsidiol production in the fruit tissue was markedly increased by the treatment with a biotic elicitor and reached its maximum level after 4 days of elicitation. The effects of separation parameters such as temperature, pressure, supercritical solvent flow rate, particle diameter and also initial capsidiol concentration were investigated on solubility, initial extraction rate and extraction yield. The optimal extraction conditions were obtained at the temperature of 40 °C, the pressure of 400 bar, the supercritical CO2 flow rate of 2 cm3 min,1, and the average particle diameter of 116 µm. The results showed that the ratio of the supercritical CO2 extraction yield to the organic solvent extraction yield was changed from 84 to 97 wt-% depending on the initial capsidiol concentration. Copyright © 2004 Society of Chemical Industry [source] | ||||||||||