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Chromatographic Peaks (chromatographic + peak)
Selected AbstractsRapid and simple method for determination of N, -(carboxymethyl)lysine and N, -(carboxyethyl)lysine in urine using gas chromatography[sol ]mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 9 2005Robert Petrovi Abstract A new procedure was developed to determine in urine the concentrations of N, -(carboxymethyl)lysine (CML) and N, -(carboxyethyl)lysine (CEL), the major products of oxidative modification of glycated proteins, to assess levels of oxidative stress in physiological systems. The urine samples were acetonitrile-deproteinized, then derivatized by ethylchloroformate, and N(O,S)-ethoxycarbonyl ethyl esters of amino acids were analysed by isotope dilution gas chromatography[sol ]mass spectrometry. Recovery averaged 89%. Linearity was excellent (r = 0.998,0.999) in the 0.5,25 µmol[sol ]L range for CML and CEL. The limit of detection of this assay was 0.1 µmol[sol ]L (corresponding to 0.20 pmol of CML or CEL on column). Intra-day and inter-day precisions were likewise excellent, with relative standard deviations <4.63 and <6.15%, respectively. Accuracy of CML and CEL determination (15 µmol[sol ]L) was 2.9 and 5.9% of the estimated theoretical value. The time from obtaining the urine sample to determination of the concentration from the chromatographic peak was 80 min or less. This method is sensitive, reproducible, accurate, relatively cheap and very simple. It can be useful for laboratories involved in the diagnosis and monitoring of age-related chronic diseases. Copyright © 2005 John Wiley & Sons, Ltd. [source] A rapid and simple method for determination of halothane, iso,urane and sevo,urane in blood using gas chromatographyBIOMEDICAL CHROMATOGRAPHY, Issue 9 2004Richard J. Atherley Abstract We have developed a technique to determine the concentration of volatile anesthetics (halothane, iso,urane and sevo,urane) in blood that is a modi,cation of a method used for volatile anesthetics in Krebs solution. Methylene chloride was the internal standard and chloroform was used to extract the volatile anesthetic from blood. The congealed blood proteins were separated from the chloroform solvent (containing anesthetic) using a two-compartment vial that ,ltered out the proteinaceous material during centrifuging. Recovery averaged 102%. Linearity was excellent (r = 0.992,0.999) in the 50,600, 50,300 and 50,300 µg/mL range for halothane, iso,urane and sevo,urane, respectively. Intra-day and inter-day precisions were likewise excellent, with relative standard deviations <5.3 and <7.1%, respectively. Accuracy ranged from 0.8 to 9.5% of the estimated theoretical value. Extracted anesthetic in chloroform solvent was stable over 4,5 days, with <3% variability. The time from obtaining the blood sample to determination of the concentration from the chromatographic peak was 15 min or less. Copyright © 2004 John Wiley & Sons, Ltd. [source] Automated software-guided identification of new buspirone metabolites using capillary LC coupled to ion trap and TOF mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 2 2006Anabel S. Fandiño Abstract The identification and structure elucidation of drug metabolites is one of the main objectives in in vitro ADME studies. Typical modern methodologies involve incubation of the drug with subcellular fractions to simulate metabolism followed by LC-MS/MS or LC-MSn analysis and chemometric approaches for the extraction of the metabolites. The objective of this work was the software-guided identification and structure elucidation of major and minor buspirone metabolites using capillary LC as a separation technique and ion trap MSn as well as electrospray ionization orthogonal acceleration time-of-flight (ESI oaTOF) mass spectrometry as detection techniques. Buspirone mainly underwent hydroxylation, dihydroxylation and N -oxidation in S9 fractions in the presence of phase I co-factors and the corresponding glucuronides were detected in the presence of phase II co-factors. The use of automated ion trap MS/MS data-dependent acquisition combined with a chemometric tool allowed the detection of five small chromatographic peaks of unexpected metabolites that co-eluted with the larger chromatographic peaks of expected metabolites. Using automatic assignment of ion trap MS/MS fragments as well as accurate mass measurements from an ESI oaTOF mass spectrometer, possible structures were postulated for these metabolites that were previously not reported in the literature. Copyright © 2006 John Wiley & Sons, Ltd. [source] Combination of GC-MS with local resolution for determining volatile components in si-wu decoctionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1-2 2003Fan Gong Abstract In this paper, the combination of gas chromatography-mass spectrometry with chemometric local resolution techniques such as subwindow factor analysis (SFA) and orthogonal projection resolution (OPR) is investigated as a method of determining volatile components present in a traditional Chinese medicinal formulation known as si-wu decoction and its two individual herbs Rhizoma chuanxiong and Radix angelicae sinensis. In order to validate the reliability of the results obtained, the volatile components of interest were further separated on open glass columns and then analyzed in the same way as above. With the help of SFA and OPR approaches, the purity of chromatographic peaks can first be identified. Then, the pure chromatogram and mass spectrum of each component involved in a target peak cluster can be easily resolved and subsequently subjected to similarity searches in the NIST MS database to qualitatively and quantitatively determine the volatile components. Our results showed that about 127, 80, and 97 chemical components could be separated and 81, 49, and 55 of them identified, representing 83.95%, 91.86%, and 85.11% of the total relative content of volatile components from Rhizoma chuanxiong, Radix angelicae sinensis, and si-wu decoction, respectively. The results obtained in this work strongly indicate that the combination of GC-MS with chemometric local resolution methods could greatly improve the chromatographic separation ability by means of mathematical approaches. Moreover, they indicated the reliability and practicability of this combined technique. [source] HPLC,SPE,NMR hyphenation in natural products research: optimization of analysis of Croton membranaceus extract,MAGNETIC RESONANCE IN CHEMISTRY, Issue 9 2005Maja Lambert Abstract The HPLC,SPE,NMR technique was used for the analysis of a root-bark extract of Croton membranaceus. The components of the extract were separated on an analytical-size reversed-phase HPLC column, the chromatographic peaks were trapped on SPE (solid-phase extraction) cartridges after post-column dilution of the eluate with water and the compounds were eluted from the cartridges with acetonitrile- d3 into a 30 µl 600 MHz NMR probe in a fully automated procedure. The trapping efficiency of scopoletin (1), the major extract constituent, was much higher on a GP (general phase, a polystyrene-type polymer) SPE phase than on a C18 phase. Thus, under the conditions used, up to 100 µg of scopoletin per cartridge could be accumulated linearly after repeated trappings. The maximum achievable NMR signal-to-noise ratio using the GP cartridges was at least four times higher than that achievable with the C18 cartridges. It was shown that excessively long T1 relaxation times may compromise experiments in which acetonitrile- d3 is used as the cartridge eluent. Nevertheless, the sensitivity gain provided by the HPLC,SPE,NMR technique through repeated peak trappings allowed the acquisition of good-quality proton-detected 2D NMR spectra without the need for solvent suppression. Copyright © 2005 John Wiley & Sons, Ltd. [source] Analysis of chemical and metabolic components in traditional Chinese medicinal combined prescription containing Radix Salvia miltiorrhiza and Radix Panax notoginseng by LC-ESI-MS methodsBIOMEDICAL CHROMATOGRAPHY, Issue 8 2007Ying-Jie Wei Abstract High-performance liquid chromatography,electrospray ionization-mass spectrometry (LC-ESI-MS) methods were developed for the analysis of chemical and metabolic components in traditional Chinese medicinal combined prescription containing Radix Salvia miltiorrhiza and Radix Panax notoginseng (commonly known as Fufang Danshen prescription, FDP). The HPLC experiments used a reversed-phase Zorbax C18 column with the column temperature at 30°C and a binary mobile phase system consisting of aqueous formic acid (0.1%, v/v) and acetonitrile using a gradient elution at the flow rate of 1.0 mL/min. The ESI-MS was operated with a single-quadrupole mass spectrometer in both negative and positive ion modes. 36 major chromatographic peaks of FDP, including 14 saponins, 13 phenolic acids and nine diterpenoid quinones were characterized by their MS spectra and in comparison with some of the reference standards. In addition, after oral administration of extraction of FDP, the rat's plasma, urine and feces were also analyzed; 53 metabolic components including 30 original components and 23 transformative components of FDP were detected, and possible metabolic pathways of some components in FDP were given. The analysis of chemical and metabolic components in FDP by HPLC-MS methods could be a useful means of identifying the multi-components of FDP and to hint at their possible metabolic mechanism of action in the body. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||