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Preparative Separation (preparative + separation)

Distribution by Scientific Domains

Chemistry	81%

Selected Abstracts

Preparative separation of a multicomponent peptide mixture by mass spectrometry

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 2 2006
Xinli Yang
Abstract We report on the first multiplex preparative separation by mass spectrometry of bio-organic molecules in the 200,350 Da mass range that is typical for synthetic drugs. A five-component mixture consisting of two di- and three tripeptides has been separated by mass using a specially designed mass spectrometer. The instrument for preparative separations consists of an electrospray ionization (ESI) source, ion transfer optics, an electrostatic sector, and an inhomogeneous-field magnetic mass analyzer that achieves linear mass dispersion of ion beams. Protonated peptides produced by electrospray were separated, nondestructively landed on a 16-channel array of dry collector plates, and reconstituted in solution. The preparation procedures and the instrumental conditions have been optimized to maximize the ion currents. The significant features of the special mass spectrometer are high ion currents and simultaneous separation and collection of mixture components. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Preparative separation and purification of liensinine, isoliensinine and neferine from seed embryo of Nelumbo nucifera GAERTN using high-speed counter-current chromatography

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2009
Shao Liu
Abstract A preparative high-speed counter-current chromatography method for separation and purification of liensinine, isoliensinine and neferine from seed embryo of Nelumbo nucifera GAERTN was successfully established by using n -hexane-ethyl acetate-methanol-water (5:8:4:5, v/v, containing 0.5% NH4OH) as the two-phase solvent system. From 200 mg of crude extract, 18.4 mg of liensinine, 19.6 mg of isoliensinine and 58.4 mg of neferine were obtained with the purity of 96.8, 95.9, and 98.6%, respectively. The identification of the three alkaloids was performed with 1H NMR and 13C NMR. [source]

Preparative separation of the saponin lancemaside a from Codonopsis lanceolata by centrifugal partition chromatography

PHYTOCHEMICAL ANALYSIS, Issue 5 2008
Osamu Shirota
Abstract Introduction. Lancemaside A is a saponin that inhibits decreases in blood testosterone level and thus prevents or ameliorates symptoms associated with male climacteric disorder. Our initial attempt to preparative isolation of lancemaside A from the saponin fraction of Codonopsis lanceolata roots by a preparative HPLC did not give a clear result. Objective. To develop a simple and efficient method for the preparative isolation of lancemaside A from the hot water extract of C. lanceolata roots using centrifugal partition chromatography (CPC). Methodology. The saponin fraction obtained from the hot water extract of C. lanceolata roots was used as the sample for preparative-scale separation of lancemasides by CPC using n -hexane:n -butanol:methanol:0.1% aqueous formic acid (3:4:1:6, v/v) as the two-phase solvent system. The upper phase (organic phase) of the two-phase solvent system was used as the mobile phase, and 0.5 g of saponin fraction was applied for separation by CPC. Each fraction that was separated by CPC was analysed by HPLC, and the fractions containing each of the separated compounds were pooled together, and then were purified by simple preparative HPLC. Results. The demonstrated separation sequence, hot water extraction, DIAION HP-20 column chromatography, CPC and preparative HPLC, yielded lancemaside A, foetidissimoside A and astersaponin Hb in their pure forms. Conclusion. The simple and efficient method for the preparative isolation of lancemaside A along with two other saponins, foetidissimoside A and astersaponin Hb, from the saponin fraction of C. lanceolata was established using CPC. [source]

Cover Picture: Electrophoresis 13/2008

ELECTROPHORESIS, Issue 13 2008
Article first published online: 11 JUL 200
Issue 13 is a regular issue including an Emphasis Section offering a series of 10 papers on "Fundamentals and Methodologies". These papers are related to peptide isoelectric point calculation, DNA separation by MEKC, modeling mobility of apothioneins, protein expression in osteoarthritis, capillary coating, preparative separation of proteins by dynamic field gradient focusing, determination of pKa, speciation analysis by CE-inductively coupled plasma MS, etc. [source]

Improved automated extraction and separation procedure for soil lipid analyses

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2004
G. L. B. Wiesenberg
Summary Analysis of soil lipids may contribute to an improved understanding of atmosphere to soil carbon fluxes, soil organic matter source differentiation and pollutant accumulation. Soil lipids, mostly originating from plants and microorganisms, have traditionally been analysed by non-automated extraction and separation methods, which produce several lipid fractions, operationally defined by polarity. Here we present a combination of fast, automated and reproducible techniques, adopted from organic geochemical studies, for preparative separation of individual soil lipid fractions with increasing polarity. These techniques involve commercially available instruments, including accelerated solvent extraction and a two-step automated medium-pressure liquid chromatography procedure. The method yields eight lipid fractions consisting of five fractions fully amenable to gas chromatography/mass spectrometry (GC/MS) (aliphatic hydrocarbons, aromatic hydrocarbons, ketones, alcohols, carboxylic acids), and three fractions of highly polar or high molecular weight compounds (bases, very long-chain wax esters (C40+), high polarity compounds) that were not measurable with GC/MS under standard conditions. We tested the method on five agricultural soils. Results show that (i) mass recoveries for the individual fractions are reproducible, (ii) within individual fractions compound distribution patterns are reproducible, as demonstrated for alkanes and carboxylic acids, and (iii) individual fractions represent distinct and clean compound classes, free of interfering substances detectable by GC/MS. Thus, automated separation can be a fast, effective and reproducible procedure for fractionation of complex mixtures of soil lipids into clean compound classes, directly suitable for a variety of molecular (e.g. GC/MS) and isotopic characterizations (e.g. gas chromatography coupled with isotope ratio monitoring mass spectrometry or accelerator mass spectrometry). [source]

Preparative separation of a multicomponent peptide mixture by mass spectrometry

Isolation and purification of macrocyclic components from Penicillium fermentation broth by high-speed counter-current chromatography

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2010
Xiang Gao
Abstract In this paper, high-speed counter-current chromatography (HSCCC), assisted with ESI-MS, was first successfully applied to the preparative separation of three macrolide antibiotics, brefeldin A (12.6,mg, 99.0%), 7,- O -formylbrefeldin A (6.5,mg, 95.0%) and 7,- O -acetylbrefeldin A (5.0,mg, 92.3%) from the crude extract of the microbe Penicillium SHZK-15. Considering the chemical nature and partition coefficient (K) values of the three target compounds, a two-step HSCCC isolation protocol was developed in order to obtain products with high purity. In the two-step method, the crude ethyl acetate extract was first fractionated and resulted in two peak fractions by HSCCC using solvent system n -hexane/ethyl acetate/methanol/water (HEMWat) (3:7:5:5,v/v/v/v), then purified using solvent systems HEMWat (3:5:3:5,v/v/v/v) and HEMWat (7:3:5:5,v/v/v/v) for each fraction. The purities and structures of the isolated compounds were determined by HPLC, X-ray crystallography, ESI-MS and NMR. The results demonstrated that HSCCC is a fast and efficient technique for systematic isolation of bioactive compounds from the microbes. [source]

Preparative isolation and purification of four flavonoids from the petals of nelumbo nucifera by high-speed counter-current chromatography

PHYTOCHEMICAL ANALYSIS, Issue 3 2010
Xingfeng Guo
Abstract Introduction , Flavonoids, the primary constituents of the petals of Nelumbo nucifera, are known to have antioxidant properties and antibacterial bioactivities. However, efficient methods for the preparative isolation and purification of flavonoids from this plant are not currently available. Objective , To develop an efficient method for the preparative isolation and purification of flavonoids from the petals of N. nucifera by high-speed counter-current chromatography (HSCCC). Methodology , Following an initial clean-up step on a polyamide column, HSCCC was utilised to separate and purify flavonoids. Purities and identities of the isolated compounds were established by HPLC-PAD, ESI-MS, 1H-NMR and 13C-NMR. Results , The separation was performed using a two-phase solvent system composed of ethyl acetate,methanol,water,acetic acid (4,:,1,:,5,:,0.1, by volume), in which the upper phase was used as the stationary phase and the lower phase was used as the mobile phase at a flow-rate of 1.0,mL/min in the head-to-tail elution mode. Ultimately, 5.0,mg syringetin-3- O-, -d-glucoside, 6.5,mg quercetin-3- O-, -d-glucoside, 12.8,mg isorhamnetin-3- O-, -d-glucoside and 32.5,mg kaempferol-3- O-, -d-glucoside were obtained from 125,mg crude sample. Conclusion , The combination of HSCCC with a polyamide column is an efficient method for the preparative separation and purification of flavonoids from the petals of N. nucifera. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Preparative separation of a multicomponent peptide mixture by mass spectrometry

Enantioseparation of extended metal atom chain complexes: Unique compounds of extraordinarily high specific rotation

CHIRALITY, Issue 3 2007
Molly M. Warnke
Abstract Extended metal atom chains (EMACs) contain a linear metal chain wrapped by various ligands. Most complexes are of the form M3(dpa)4X2, where M = metal, dpa = 2,2,-dipyridylamide, and X = various anions. The ligands form helical coils about the metal chain, which results in chiral EMAC complexes. The EMACs containing the metals Co and Cu were partially separated in polar organic mode using a vancomycin-based chiral stationary phase. Under similar conditions, two EMACs with Ni metal and varying anions could be baseline separated. The polar organic mode was used because of the instability of the compounds in aqueous mobile phases. Also, these conditions are more conducive to preparative separations. Polarimetric measurements on the resolved enantiomers of Ni3(dpa)4Cl2 indicate that they have extraordinarily high specific rotations (on the order of 5000 deg cc/g dm). Chirality, 2007. © 2006 Wiley-Liss, Inc. [source]

Chiral separations on polysaccharide stationary phases using polar organic mobile phases

CHIRALITY, Issue 1 2006
Kenneth G. Lynam
Abstract About 30% of a chemically diverse set of compounds were found to separate on four polysaccharide chiral stationary phases using polar organic mobile phases. No structural features appeared to correlate to successful separations. Titrations between normal and polar organic mobile phases suggested that separation mechanisms do not differ between these mobile phases. Attempts made to control retention met with varying degrees of success. Addition of hexane to alcohols had minor effects on retention although this was occasionally beneficial. Addition of water to alcohols increased retention. Addition of water to acetonitrile decreased retention. Addition of alcohol to acetonitrile also proved beneficial to the separation of some compounds. Loading studies performed to mimic preparative separations indicated that the benefits of polar organic mobile phases are largely due to increased solubility. © 2005 Wiley-Liss, Inc. Chirality [source]