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Chromatographic Run (chromatographic + run)
Terms modified by Chromatographic Run Selected AbstractsThe influence of cytosine methylation on the chemoselectivity of benzo[a]pyrene diol epoxide-oligonucleotide adducts determined using nanoLC/MS/MSJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 8 2009James Glick Abstract Benzo[a]pyrene is a major carcinogen implicated in human lung cancer. Almost 60% of human lung cancers have a mutation in the p53 tumor suppressor gene at several specific codons. An on-line nanoLC/MS/MS method using a monolithic nanocolumn was applied to investigate the chemoselectivity of the carcinogenic diol epoxide metabolite, ( ± )-(7R,8S,9S,10R)-benzo[a]pyrene 7,8-diol 9,10-epoxide [( ± )- anti -benzo[a]pyrene diol epoxide (BPDE)], which was reacted in vitro with a synthesized 14-mer double stranded oligonucleotide (5,-ACCCG5CG7TCCG11CG13C-3,/5,-GCGCGGGCGCGGGT-3,) derived from the p53 gene. This sequence contained codons 157 and 158, which are considered mutational ,hot spots' and have also been reported as chemical ,hot spots' for the formation of BPDE-DNA adducts. In evaluating the effect of cytosine methylation on BPDE-DNA adduct binding, it was found that codon 156, containing the nucleobase G5 instead of the mutational hot spot codons 157 (G7) and 158 (G11), was the preferential chemoselective binding site for BPDE. In all permethylated cases studied, the relative ratio for adduction was found to be G5, G11 > G13 > G7. Permethylation of CpG dinucleotide sites on either the nontranscribed or complementary strand did not change the order of sequence preference but did enhance the relative adduction level of the G11 CpG site (codon 158) approximately two-fold versus the unmethylated oligomer. Permethylation of all CpG dinucleotide sites on the duplex changed the order of relative adduction to G5, G7 > G11 > G13. The three- to four-fold increase in adduction at the mutational hot spot codon 157 (G7) relative to the unmethylated or single-stranded permethylated cases suggests a possible relationship between the state of methylation and adduct formation for a particular mutation site in the p53 gene. Using this method, only 125 ng (30 pmol) of adducted oligonucleotide was analyzed with minimal sample cleanup and high chromatographic resolution of positional isomers in a single chromatographic run. Copyright © 2009 John Wiley & Sons, Ltd. [source] Off-line combination of reversed-phase liquid chromatography and laser desorption/ionization time-of-flight mass spectrometry with seamless post-source decay fragment ion analysis for characterization of square-planar nickel(II) complexesJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2006Pavel, ehulka Abstract Characterization of square-planar nickel(II) complexes of the Schiff base of (S)- N -benzylproline (2-benzoylphenyl)amide and various amino acids that are used as efficient ,-amino acids synthons was carried out using laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS) in off-line combination with liquid chromatography. A mixture of four square-planar nickel(II) complexes was separated using reversed-phase liquid chromatography (RPLC) and the separated fractions from the chromatographic run were spotted on the metal target directly from the column outlet using a lab-made sample deposition device. The separated fractions were then analyzed by LDI-TOF MS. Seamless postsource decay (sPSD) fragment ion analysis was used for their structural characterization, which made possible the confirmation of expected chemical structures of the analyzed compounds. The off-line combination of the separation by RPLC and analysis by LDI-TOF MS allowed successful separation, sensitive detection and structure elucidation of the square-planar nickel(II) complexes. Copyright © 2006 John Wiley & Sons, Ltd. [source] Analysis of immunoglobulin glycosylation by LC-ESI-MS of glycopeptides and oligosaccharidesPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 14 2008Johannes Stadlmann Abstract Two LC-ESI-MS methods for the analysis of antibody glycosylation are presented. In the first approach, tryptic glycopeptides are separated by RP chromatography and analyzed by ESI-MS. This "glycopeptide strategy" allows a protein- and subclass-specific quantitation of both neutral and sialylated glycan structures. Additional information about under- or deglycosylation and the protein backbone, e.g., termini, can be extracted from the same data. In the second LC-ESI-MS method, released oligosaccharides are separated on porous graphitic carbon (PGC). A complete structural assignment of neutral and sialylated oligosaccharides occurring on antibodies is thereby achieved in one chromatographic run. The two methods were applied to polyclonal human IgG, to commercial mAb expressed in CHO cells (Rituximab, Xolair, and Herceptin), in SP2/0 (Erbitux and Remicade) or NS0 cells (Zenapax) and the anti-HIV antibody 4E10 produced either in CHO cells or in a human cell line. Both methods require comparably little sample preparation and can be applied to SDS-PAGE bands. They both outperform non-MS methods in terms of reliability of peak assignment and MALDI-MS of underivatized glycans with regard to the recording of sialylated structures. Regarding fast and yet detailed structural assignment, LC-MS on graphitic carbon supersedes all other current methods. [source] Nitrogen purity influences the occurrence of As+ ions in high-performance liquid chromatography/electrospray ionization mass spectrometric analysis of four common arsenosugarsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2003Doris Kuehnelt High-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC/ESI-MS) can provide both elemental and molecular information and, therefore, is a very useful tool for the identification of arsenic compounds. When a method for the identification of four arsenosugars was employed in our laboratory with an HPLC/ESI-MS system equipped with a Whatman model 75-72 nitrogen generator, a signal at m/z 75 (As+) could not be observed. When the HPLC/ESI-MS system was operated with nitrogen 5.0 (nitrogen of a purity of at least 99.999%) all four arsenosugars gave a signal at m/z 75. Because of this observation the influence of the quality of the nitrogen drying gas on the fragmentation of the four arsenosugars was systematically investigated. Standard solutions containing the four arsenosugars (0.5 ng As each) were separated on an anion-exchange column and detected with ESI-MS in the positive ion mode by monitoring the signals for [M+H]+, m/z 237, 91, and 75. Nitrogen with defined oxygen concentrations was used as drying gas. The purity of the nitrogen ranged from 99 to 99.999% (10,400 to 10 ppm oxygen impurity). The nitrogen with 99% purity gave no signal at m/z 75, but signals were obtained at m/z 91, 237, and for [M+H]+. When higher purity nitrogen (99.9%) was used, a signal was obtained at m/z 75, which accounted for 0.8,1.1% (depending on the kind of arsenosugar) of the sum of the signals for m/z 75, 91, 237 and [M+H]+. As the level of oxygen in the nitrogen decreased, the m/z 75 signal increased to 2.0,3.1%. This was accompanied by a concomitant decrease in the m/z 91 signal from 5.2,6.6% to 0.7,1.5%, whereas the signals for [M+H]+ and m/z 237 were essentially unchanged. Signals at m/z 75 with intensities comparable with those observed for the 99.9% pure nitrogen were also obtained for all the arsenosugars when the HPLC/ESI-MS system was operated with a Domnick Hunter Nitrox UHPLCMS18 nitrogen generator. Dimethylarsinic acid, arsenobetaine, trimethylarsine oxide, arsenocholine and the tetramethylarsonium cation also gave no signal at m/z 75 when they were analyzed with the Whatman model 75-72 nitrogen generator, but clear signals at m/z 75 were observed with the Domnick Hunter Nitrox UHPLCMS18 nitrogen generator. A nitrogen quality of at least 99.9% is required to obtain elemental information (m/z 75) when arsenic compounds are investigated by HPLC/ESI-MS. Molecular and elemental information from one chromatographic run is a valuable tool for the characterization of unknown arsenic compounds. Copyright © 2003 John Wiley & Sons, Ltd. [source] A sensitive liquid chromatography,electrospray ionization,mass spectrometry method for the simultaneous determination of pentoxyverine citrate and guaifenesin in human plasma,application to pharmacokinetic and bioequivalence studiesBIOMEDICAL CHROMATOGRAPHY, Issue 4 2010Jinhua Wen Abstract A sensitive and specific liquid chromatography,electrospray ionization,mass spectrometry method for the identification and quantification of pentoxyverine citrate and guaifenesin in human plasma has been developed. After extraction from plasma samples by ethyl acetate, the internal standard and analytes were separated by high-performance liquid chromatographic on a Shim-pack VP-ODS C18 column (150 × 2.0 mm) using a mobile phase consisting of A (methanol) and B (0.4% glacial acetic acid and 4 mmol/L ammonium acetate) (A:B, 43 : 57). Analysis was performed on a Shimadzu LC/MS-2010A in selected ion monitoring mode with a positive electrospray ionization interface. The method was linear in the concentration range of 1.0,640.0 ng/mL for pentoxyverine citrate and 0.025,6.4 ,g/mL for guaifenesin. The inter- and intra- precision were all within 12% and accuracy ranged from 85 to 115%. The lower limits of quantification were 1.0 ng/mL for pentoxyverine citrate and 25.0 ng/mL for guaifenesin. The extraction recovery was on average 81.95% for pentoxyverine citrate and 89.03% for guaifenesin. This is the first assay method reported for the simultaneous determination of pentoxyverine citrate and guaifenesin in plasma using one chromatographic run. Copyright © 2009 John Wiley & Sons, Ltd. [source] Linear retention indices in gas chromatographic analysis: a reviewFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2008Barbara d'Acampora Zellner Abstract The main purpose of any chromatographic analysis is to resolve mixtures of compounds into less complex mixtures or ultimately into pure components. In addition to this function, the chromatographic system can provide retention data which serve as complementary information for the positive identification of resolved components. The need to express gas chromatographic retention data in a standardized system has long been recognized and retention index values presented to be a valuable parameter. Those values are mainly calculated by applying the equations proposed by Kováts, for isothermal analysis, and van den Dool and Kratz, for programmed gas chromatographic runs. In general, these indices denote the retention behaviour of the compounds of interest according to a uniform scale determined by a series of closely related standard substances. The use of retention indices in the flavour and fragrance field is well-documented, and they are widely applied for the comparison of results between laboratories, as well as to characterize stationary phases. Copyright © 2008 John Wiley & Sons, Ltd. [source] Isolation of ATP from a yeast fermentation broth using a cryogel column at high flow velocitiesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 22 2008Chen Yan Abstract This communication presents an effective method for isolating adenosine triphosphate (ATP) from a yeast fermentation broth using an anion-exchange supermacroporous cryogel column at high flow velocities. The breakthrough and elution behaviors of pure ATP in the cryogel bed were investigated at flow velocities of 2, 5, and 10 cm/min and the ATP binding capacities were determined. Then the ATP-containing yeast fermentation broth was employed as the test feedstock and various chromatographic runs were conducted to isolate ATP by the cryogel at different high flow velocities. The ATP samples obtained were analyzed quantitatively by HPLC. The results showed that even at a flow velocity of 5 or 10 cm/min, a product purity of 97.4 or 98.0% can be achieved, illustrating the potential of the present method for separation of high-purity ATP directly from fermentation feedstock at high flow velocities. [source] Development and validation of a liquid chromatography/tandem mass spectrometric method for the determination of 39 mycotoxins in wheat and maizeRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2006Michael Sulyok This paper describes the first validated method for the determination of 39 mycotoxins in wheat and maize using a single extraction step followed by liquid chromatography with electrospray ionization triple quadrupole mass spectrometry (LC/ESI-MS/MS) without the need for any clean-up. The 39 analytes included A- and B-trichothecenes (including deoxynivalenol-3-glucoside), zearalenone and related derivatives, fumonisins, enniatins, ergot alkaloids, ochratoxins, aflatoxins and moniliformin. The large number and the chemical diversity of the analytes required the application of the positive as well as the negative ion ESI mode in two consecutive chromatographic runs of 21,min each. The solvent mixture acetonitrile/water/acetic acid 79,+,20,+,1 (v/v/v) has been determined as the best compromise for the extraction of the analytes from wheat and maize. Raw extracts were diluted 1,+,1 and were injected without any clean-up. Ion-suppression effects due to co-eluting matrix components were negligible in the case of wheat, whereas significant signal suppression for 12 analytes was observed in maize, causing purely proportional systematic errors. Method performance characteristics were determined after spiking blank samples on multiple levels in triplicate. Coefficients of variation of the overall process of <5.1% and <3.0% were obtained for wheat and maize, respectively, from linear calibration data. Limits of detection ranged from 0.03 to 220,µg/kg. Apparent recoveries (including both the recoveries of the extraction step and matrix effects) were within the range of 100,±,10% for approximately half of the analytes. In extreme cases the apparent recoveries dropped to about 20%, but this could be compensated for to a large extent by the application of matrix-matched standards to correct for matrix-induced signal suppression, as only a few analytes such as nivalenol and the fumonisins exhibited incomplete extraction. For deoxynivalenol and zearalenone, the trueness of the method was confirmed through the analysis of certified reference materials. Copyright © 2006 John Wiley & Sons, Ltd. [source] Validation of a real-time monitoring method for aniline in freshwater by high-performance liquid chromatography on porous graphitic carbon/electrospray ionization tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 14 2004Raphaël Delépée Aniline is an anthropogenic organic compound widely used in polymer, rubber, pharmaceutical and dye industries but also used in biodegradability assays of chemical compounds as a positive biodegradation standard. By the two approaches, the rapid determination of aniline is necessary because of the high toxicity of aniline on hemoglobin. A high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) method for the determination of aniline in water is described here. This method, using benzylamine as internal standard, was validated. No time-consuming sample preparation was needed. A rapid separation (7,min between two chromatographic runs) of aniline and benzylamine was performed on a Hypercarb porous graphitic carbon column using a gradient of methanol and 100,mM formic acid. The obtained limits of detection and quantification were 10 and 1,ng/mL, respectively. The response for aniline was quadratic. We show that this problem could be circumvented by showing that the [calculated concentration,=,f(introduced concentration)] function was linear. The linearity range was 10,1000,ng/mL. An example of an application consisting of an aniline 42-day degradation kinetic in water was demonstrated. Copyright © 2004 John Wiley & Sons, Ltd. [source] Stereospecificity and stereoselectivity of flobufen metabolic profile in male rats in vitro and in vivo: Phase I of biotransformationCHIRALITY, Issue 10 2001Vladimír Wsól Abstract Flobufen (F) is the original nonsteroidal antiinflammatory drug (NSAID) containing two enantiomers. The aim of this investigation was to elucidate the biotransformation pathway of F at chiral level in phase I of biotransformation. Stereoselectivity and stereospecificity of the respective enzymes were studied in male rats in vitro (microsomal and cytosolic fractions, hepatocytes suspension) and in vivo. The rac -F, (+)-R-F and (,)-S-F were used as substrates. Amounts of F enantiomers, 4-dihydroflobufen diastereoisomers (DHF) and other metabolites (M-17203, UM) were determined with a chiral HPLC method in two chromatographic runs on R,R-ULMO and allyl-terguride bonded columns. Stereoselective biotransformation of the two enantiomers of F was observed at all tested levels and significant bidirectional chiral inversion of enantiomers of F was observed in hepatocytes. Mean enantiomeric ratios of F concentrations (S-/R-), after rac -F incubations, ranging from 1.09 in cytosolic fraction to 18.23 in hepatocytes. Stereospecificity of the respective F reductases was also observed. (2R;4S)-DHF and (2S;4S)-DHF are the principal metabolites of F in microsomes and hepatocytes. Neither DHF diastereoisomers nor M-17203 were found in cytosolic fraction. Only the nonchiral metabolite, M-17203, was found in all urine and feces samples after oral administration of F. Chirality 13:754,759, 2001. © 2001 Wiley-Liss, Inc. [source] | ||||||||||