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Quadrupole Time-of-flight Tandem Mass Spectrometry (quadrupole + time-of-flight_tandem_mass_spectrometry)

Distribution by Scientific Domains
Chemistry100%

Kinds of Quadrupole Time-of-flight Tandem Mass Spectrometry

  • ionization quadrupole time-of-flight tandem mass spectrometry
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    Selected Abstracts

    Highly Chemo- and Regioselective Reduction of Aromatic Nitro Compounds Catalyzed by Recyclable Copper(II) as well as Cobalt(II) Phthalocyanines

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010
    Upendra Sharma
    Abstract Copper/cobalt phthalocyanines were established for the first time as catalysts for the very efficient chemo- and regioselective reduction of aromatic nitro compounds to generate the corresponding amines. The selective reduction of nitro compounds was observed in the presence of a large range of functional groups such as aldehyde, keto, acid, amide, ester, halogen, lactone, nitrile and heterocyclic functional groups. Furthermore, the present method was found to be highly regioselective towards the reduction of aromatic dinitro compounds in a short time with high yields. In most of the cases the conversion and selectivity were >99% as monitored by GC-MS. The reduction mechanism was elucidated by UV-vis and electrospray ionization quadrupole time-of-flight tandem mass spectrometry. [source]

    Characterisation of oxazepam degradation products by high-performance liquid chromatography/electrospray ionisation mass spectrometry and electrospray ionisation quadrupole time-of-flight tandem mass spectrometry

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 5 2010
    Thomas J. P. Smyth
    Oxazepam has been subjected to controlled degradation at 100°C for 3,h in 0.5,M HCl and 0.5,M NaOH. Following neutralisation of the degradation mixture and removal of salts by solid-phase extraction (SPE), isocratic high-performance liquid chromatography/mass spectrometry (HPLC/MS) using water/methanol (25:75,v/v) as the mobile phase was carried out using a flow diverter to collect fractions prior to their characterisation by electrospray ionisation multi-stage mass spectrometry (ESI-MSn) and proposal of the corresponding fragmentation patterns. The elemental compositions of the degradation products and their MS fragments were evaluated using electrospray ionisation quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) which was then used to support the proposed fragmentation patterns. Copyright © 2010 John Wiley & Sons, Ltd. [source]

    Elucidation of the molecular structure of lipid A isolated from both a rough mutant and a wild strain of Aeromonas salmonicida lipopolysaccharides using electrospray ionization quadrupole time-of-flight tandem mass spectrometry

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2005
    Anas El-Aneed
    The chemical structure of lipid A, isolated by mild acid hydrolysis from a rough mutant and a wild strain of Aeromonas salmonicida lipopolysaccharide, was investigated using electrospray ionization quadrupole time-of-flight (QqToF) hybrid tandem mass spectrometry and showed a great degree of microheterogeneity. The chemical structure of the main constituent of this heterogeneous mixture was identified as a , -D-(1,,,6) linked D-glucosamine disaccharide substituted by two phosphate groups, one being bound to the non-reducing end at position O-4, and the other to the position O-1 of the reducing end of the D-glucosamine disaccharide. The location of the fatty acids linked to the disaccharide backbone was established by identifying diagnostic ions in the conventional QqToF-MS scan. Low-energy collision tandem mass spectrometry analysis of the selected precursor diagnostic ions confirmed, unambiguously, their proposed molecular structures. We have established that myristyloxylauric (C14:0(3- O(12:0))) acid residues were both N-2, and O-3, linked to the non-reducing end of the D-GlcN residue, and that two 3-hydroxymyristic (C14:0(3-OH)) acid chains acylated the remaining positions of the reducing end. The MS and MS/MS data obtained allowed us to determine the complex molecular structure of lipid A. The QqToF-MS/MS instrument has shown excellent superiority over a conventional quadrupole-hexapole-quadrupole tandem instrument which failed to fragment the selected precursor ion. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Identification of monovinyl tripropionic acid porphyrins and metabolites from faeces of patients with hereditary coproporphyria by high-performance liquid chromatography/electrospray ionization quadrupole time-of-flight tandem mass spectrometry

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2004
    Malcolm Danton
    The original article to which this Erratum refers was published in Rapid Commun. Mass Spectrom. 2004; 18: 2309,2316 [source]

    Quantification of clenbuterol in equine plasma, urine and tissue by liquid chromatography coupled on-line with quadrupole time-of-flight mass spectrometry

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2002
    Fuyu Guan
    Clenbuterol (CBL) is a potent ,2 -adrenoceptor agonist used for the management of respiratory disorders in the horse. The detection and quantification of CBL can pose a problem due to its potency, the relatively low dose administered to the horse, its slow clearance and low plasma concentrations. Thus, a sensitive method for the quantification and confirmation of CBL in racehorses is required to study its distribution and elimination. A sensitive and fast method was developed for quantification and confirmation of the presence of CBL in equine plasma, urine and tissue samples. The method involved liquid-liquid extraction (LLE), separation by liquid chromatography (LC) on a short cyano column, and pseudo multiple reaction monitoring (pseudo-MRM) by electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS). At very low concentrations (picograms of CBL/mL), LLE produced better extraction efficiency and calibration curves than solid-phase extraction (SPE). The operating parameters for electrospray QTOF and yield of the product ion in MRM were optimized to enhance sensitivity for the detection and quantification of CBL. The quantification range of the method was 0.013,10,ng of CBL/mL plasma, 0.05,20,ng/0.1,mL of urine, and 0.025,10,ng/g tissue. The detection limit of the method was 13,pg/mL of plasma, 50,pg/0.1,mL of urine, and 25,pg/g of tissue. The method was successfully applied to the analysis of CBL in plasma, urine and various tissue samples, and in pharmacokinetic (PK) studies of CBL in the horse. CBL was quantified for 96,h in plasma and 288,h in urine post-administration of CLB (1.6,µg/kg, 2,×,daily,×,7 days). This method is useful for the detection and quantification of very low concentrations of CBL in urine, plasma and tissue samples. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    Identification of N -linked oligosaccharide labeled with 1-pyrenesulfonyl chloride by quadrupole time-of-flight tandem mass spectrometry after separation by micro- and nanoflow liquid chromatography

    BIOMEDICAL CHROMATOGRAPHY, Issue 9 2009
    Jun Zhe Min
    Abstract The development of a qualitative determination method for the N -linked oligosaccharides in glycoproteins was attempted by the combination of micro- or nanoflow LC with Q-TOF-MS/MS. The asparaginyl-oligosaccharides in glycoproteins, liberated from the treatment of Pronase E, were separated, purified and labeled with 1-pyrenesulfonyl chloride (PSC). The resulting derivatives were separated by the microflow LC system utilizing a 0.5 mm diameter microcolumn or nanoflow LC system utilizing a 75 µm diameter chip column. The eluted N -linked oligosaccharide derivatives were then introduced into the Q-TOF-MS instrument and sensitively detected in the ESI+ mode. Several factors (i.e. fragmentor, skimmer, Vcap voltages and collision energy) affecting the sensitivity of Q-TOF-MS/MS detection were optimized in both the micro- and nanoflow LC systems. Various fragment ions based on the carbohydrate units appeared on the MS/MS spectra. Among the peaks, m/z 600.16 corresponding to PSC-labeled Asp-HexNAc is the most important one to identify the asparaginyl-oligosaccharide. The N -linked oligosaccharides in the ovalbumin were easily identified by the selected-ion chromatogram at m/z 600.16 by the MS/MS detection. Therefore, the identification of N -linked oligosaccharides in glycoproteins seems to be possible by the proposed micro- and nanoflow LC separations followed by the Q-TOF-MS/MS detection. Copyright © 2009 John Wiley & Sons, Ltd. [source]