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Ion Electrospray (ion + electrospray)

Distribution by Scientific Domains
Chemistry100%

Terms modified by Ion Electrospray

  • ion electrospray ionization
    		•

    Selected Abstracts

    Quantitative analysis of EO9 (apaziquone) and its metabolite EO5a in human plasma by high-performance liquid chromatography under basic conditions coupled to electrospray tandem mass spectrometry

    JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 10 2006
    Liia D. Vainchtein
    A sensitive and specific LC-MS/MS assay for the quantitative determination of EO9 and its metabolite EO5a is presented. A 200-µl human plasma aliquot was spiked with a mixture of deuterated internal standards EO9- d3 and EO5a- d4 and extracted with 1.25 ml ethyl acetate. Dried extracts were reconstituted in 0.1 M ammonium acetate,methanol (7 : 3, v/v) and 25 µl-volumes were injected into the HPLC system. Separation was achieved on a 150 × 2.1 mm C18 column using an alkaline eluent (1 mM ammonium hydroxide,methanol (gradient system)). Detection was performed by positive ion electrospray followed by tandem mass spectrometry. The assay quantifies a range from 5 to 2500 ng/ml for EO9 and from 10 to 2500 ng/ml EO5a using 200 µl of human plasma samples. Validation results demonstrate that EO9 and EO5a concentrations can be accurately and precisely quantified in human plasma. This assay will be used to support clinical pharmacologic studies with EO9. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Assigning glucose or galactose as the primary glycosidic sugar in 3- O -mono-, di- and triglycosides of kaempferol using negative ion electrospray and serial mass spectrometry

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 19 2009
    Geoffrey C. Kite
    Kaempferol 3- O - , -glucopyranoside, kaempferol 3- O - , -galactopyranoside and higher glycosides of these two flavonoids with , -rhamnose at C-2 and/or C-6 of the primary sugar were studied by negative ion electrospray ionisation and serial mass spectrometry in a three-dimensional (3D) ion trap mass spectrometer. Kaempferol 3- O - , -glucopyranoside and kaempferol 3- O - , -rhamnopyranosyl(1,6)- , -glucopyranoside could be distinguished from their respective galactose analogues by differences in the ratio of the radical aglycone ion [Y0 , H],, to the rearrangement aglycone ion Y following MS/MS of the deprotonated molecules. Kaempferol 3- O -rhamnopyranosyl(1,2)- , -glucopyranoside and kaempferol 3- O - , -rhamnopyranosyl(1,2)[, -rhamnopyranosyl(1,6)]- , -glucopyranoside could be distinguished from their respective galactose analogues by differences in the product ion spectra of the [(M , H) , rhamnose], ion following serial mass spectrometry. In the triglycoside, it was deduced that this ion resulted from the loss of the rhamnose substituted at 2-OH of the primary sugar by observing that MS/MS of deprotonated kaempferol 3- O - , -glucopyranosyl(1,2)[, -rhamnopyranosyl(1,6)]- , -glucopyranoside showed the loss of glucose and not rhamnose. Thus the class of sugar (hexose, deoxyhexose, pentose) at C-2 and C-6 of the primary sugar can be determined. These observations aid the assignment of kaempferol 3- O -glycosides, having glucose or galactose as the primary glycosidic sugar, in LC/MS analyses of plant extracts, and this can be done with reference to only a few standards. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Separation of a BMS drug candidate and acyl glucuronide from seven glucuronide positional isomers in rat plasma via high-performance liquid chromatography with tandem mass spectrometric detection

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2006
    Y.-J. Xue
    A high-performance liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed and validated for the determination of a BMS drug candidate and its acyl glucuronide (1- O - , glucuronide) in rat plasma. A 50-µL aliquot of each plasma sample was fortified with acetonitrile containing the internal standard to precipitate proteins and extract the analytes of interest. After mixing and centrifugation, the supernatant from each sample was transferred to a 96-well plate and injected into an LC/MS/MS system. Chromatographic separation was achieved isocratically on a Phenomenex Luna C18, 3,mm,×,150,mm, 3,µm column. The mobile phase contained 0.075% formic acid in 70:30 (v/v) acetonitrile/water. Under the optimized chromatographic conditions, the BMS drug candidate and its acyl glucuronide were separated from its seven glucuronide positional isomers within 10,min. Resolution of the parent from all glucuronides and acyl glucuronide from its positional isomers was critical to avoid their interference with quantitation of parent or acyl glucuronide. Detection was by positive ion electrospray MS/MS on a Sciex API 4000. The standard curve, which ranged from 5 to 5000,ng/mL, was fitted to a 1/x2 weighted quadratic regression model for both the BMS drug candidate and its acyl glucuronide. Whole blood and plasma stability experiments were conducted to establish the sample collection, storage, and processing conditions. The validation results demonstrated that this method was rugged and repeatable. The same methodology has also been used in mouse and human plasma for the determination of the BMS drug candidate and its acyl glucuronide. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Quantitative determination of alkylated quaternary amines and their n -hydroxylated metabolites in an enzyme incubation matrix by liquid chromatography electrospray ionization mass spectrometry

    BIOMEDICAL CHROMATOGRAPHY, Issue 8 2005
    Victoria E. Holmes
    Abstract A simple, rapid and sensitive reversed-phase liquid chromatography method coupled to electrospray ionization mass spectrometry has been developed for studying the in vitro metabolism of the long-chain quaternary ammonium compounds dodecyltrimethylamine, tetradecyltrimethylamine and hexadecyltrimethylamine. Samples were prepared from the biological matrix by a simple protein precipitation stage. The separation was performed using a BDS Hypersil C8 3 µm particle size (100 × 3 mm i.d.) column with a fast gradient separation (60% B to 100% B) using a mobile phase of 10 mm aqueous ammonium acetate (pH 4.0, with 0.06% triethylamine; (A),acetonitrile (B) at 0.7 mL min,1. To minimize contamination of the MS source a switching value was used to divert the solvent front to waste. Decylammonium bromide was used as the internal standard and analytes were identified and quantified by positive ion electrospray selected ion monitoring of their intact molecular cations. The assay had a limit of quantitation of 0.25 µm (6.25 pmol on column) and was linear over the range 0.25,100 µm assay concentration for this series of long-chain quaternary amines. The precision of intra- and inter-day assays was better than 19% and the accuracy was between 93 and 109%. The method was used to assess the in vitro metabolism of the quaternary amines by wild-type cytochrome P450 enzyme CYP4A1 and mutants in an artifical membrane system. Copyright © 2005 John Wiley & Sons, Ltd. [source]