Chromatography Ion Trap Mass Spectrometry (chromatography + ion_trap_mass_spectrometry)

Distribution by Scientific Domains
Chemistry100%

Kinds of Chromatography Ion Trap Mass Spectrometry

  • liquid chromatography ion trap mass spectrometry
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    Selected Abstracts

    Analyses of second-generation ,legal highs' in the UK: Initial findings

    DRUG TESTING AND ANALYSIS, Issue 8 2010
    Simon D. Brandt
    Abstract In the UK, mephedrone and other so-called ,legal high' derivatives have recently been classified as Class B, Schedule I under the Misuse of Drugs Act 1971. Since then, alternative products have been advertised on a number of websites. In order to obtain an immediate snapshot of the situation, 24 products were purchased online from 18 UK-based websites over a period of 6 weeks following the ban in April 2010. Qualitative analyses were carried out by gas chromatography ion trap mass spectrometry using electron- and chemical ionization modes, nuclear magnetic resonance spectroscopy, and comparison with reference standards. Overall, the purchased products consisted of single cathinones or cathinone mixtures including mephedrone, butylone, 4-methyl- N -ethylcathinone, flephedrone (4-fluoromethcathinone) and MDPV (3,4-methylenedioxypyrovalerone), respectively. Benzocaine, caffeine, lidocaine, and procaine were also detected. The emphasis was placed on ,Energy 1' (NRG-1), a product advertised as a legal replacement for mephedrone-type derivatives usually claiming to contain naphyrone (naphthylpyrovalerone, O-2482). It was found that 70% of NRG-1 and NRG-2 products appeared to contain a mixture of cathinones banned in April 2010 and rebranded as ,new' legal highs, rather than legal chemicals such as naphyrone as claimed by the retailers. Only one out of 13 NRG-1 samples appeared to show analytical data consistent with naphyrone. These findings also suggest that both consumers and online sellers (unlike manufacturers and wholesalers) are, most likely unknowingly, confronted with the risk of criminalization and potential harm. Copyright © 2010 John Wiley & Sons, Ltd. [source]

    Proteome analysis of hepatocellular carcinoma cell strains, MHCC97-H and MHCC97-L, with different metastasis potentials

    PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 4 2004
    Shi-Jian Ding
    Abstract To better understand the mechanism underlying hepatocellular carcinoma (HCC) metastasis and to search for potential markers for HCC prognosis, differential proteome analysis on two HCC cell strains with high and low metastatic potentials, MHCC97-H and MHCC97-L, was conducted using two-dimensional (2-D) gel electrophoresis followed by matrix-assisted laser desorption/time of flight mass spectrometry and liquid chromatography ion trap mass spectrometry. Image analysis of silver-stained 2-D gels revealed that 56 protein spots showed significant differential expression in MHCC97-H and MHCC97-L cells (Student's t -test, P < 0.05) and 4 protein spots were only detected in MHCC97-H cells. Fourteen protein spots were further identified using in-gel tryptic digestion, peptide mass fingerprinting and tandem mass spectrometry. The expressions of pyruvate kinase M2, ubiquitin carboxy-terminal hydrolase L1, laminin receptor 67 kDa, S100 calcium-binding protein A4, thioredoxin and cytokeratin 19 were elevated in MHCC97-H cells. However, manganese superoxide dismutase, calreticulin precursor, cathepsin D, lactate dehydrogenase B, non-metastatic cell protein 1, cofilin 1 and calumenin precursor were down-regulated in MHCC97-H cells. Intriguingly, most of these identified proteins have been reported to be associated with tumor metastasis. The functional implications of alterations in the levels of these proteins are discussed. [source]

    Direct-injection high performance liquid chromatography ion trap mass spectrometry for the quantitative determination of olanzapine, clozapine and N -desmethylclozapine in human plasma

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 13 2002
    Manfred Kollroser
    A specific and sensitive direct-injection high performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) method has been developed for the rapid identification and quantitative determination of olanzapine, clozapine, and N -desmethylclozapine in human plasma. After the addition of the internal standard dibenzepin and dilution with 0.1% formic acid, plasma samples were injected into the LC/MS/MS system. Proteins and other large biomolecules were removed during an online sample cleanup using an extraction column (1,×,50,mm i.d., 30,µm) with a 100% aqueous mobile phase at a flow rate of 4,mL/min. The extraction column was subsequently brought inline with the analytical column by automatic valve switching. Analytes were separated on a 5,µm Symmetry C18 (Waters) analytical column (3.0,×,150,mm) with a mobile phase of acetonitrile/0.1% formic acid (20:80, v/v) at a flow rate of 0.5,mL/min. The total analysis time was 6,min per sample. The inter- and intra-assay coefficients of variation for all compounds were <11%. By eliminating the need for extensive sample preparation, the proposed method offers very large savings in total analysis time. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    The metabolism and excretion of 2-methylaminoethoxycarbonyl-4,4,-dimethoxy-5,6,5,,6,-dimethylenedioxybiphenyl-2,-carboxylic acid (DDB-S) in rats and human

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 13 2006
    Hye Hyun Yoo
    The metabolism and excretion of 2-methylaminoethoxycarbonyl-4,4,-dimethoxy-5,6,5,,6,-dimethylenedioxybiphenyl-2,-carboxylic acid (DDB-S) were investigated in both rats and humans using liquid chromatography/electrospray ion trap mass spectrometry (LC/ESI-MS/MS). In rats, DDB-S was rapidly eliminated from the body after a single 50,mg/kg intravenous injection, with urine being a major excretion route. DDB-S was metabolically stable; approximately 96% of the administered dose was recovered in the form of the parent compound. Nevertheless, 12 metabolites were detected in the urine and feces collected from DDB-S-treated rats. The structural characterizations of the metabolites were elucidated from the MSn spectral analysis. Because DDB-S has a pseudo-symmetrical methylenedioxy biphenyl structure, regioselective deuterium-substituted DDB-S (d5 -DDB-S) was used to assign the metabolic modification. The major metabolic pathways of DDB-S were identified as demethylenation of the methylenedioxy moiety, O-demethylation of the methoxy moiety and glucuronidation. In addition, N-demethylation of the methylaminoethyl group was also detected as a minor reaction. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Metabolite profiling in rat urine by liquid chromatography/electrospray ion trap mass spectrometry.

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2003
    Application to the study of heavy metal toxicity
    This work reports the use of reverse-phase liquid chromatography coupled to electrospray ion trap (QIT) mass spectrometry for the analysis of the metabolome in rat urine. An injection of 20,,L of urine into the chromatographic system is followed by a slow gradient elution and mass spectrometric detection in the scanning mode from m/z 100,1000 in both positive and negative modes. Over a time scale of 90,min, 30 and 20 resolved peaks were observed in the positive and the negative modes, respectively, corresponding to the presence of a few hundred m/z ratios. By using a QIT analyzer, data-dependent tandem mass spectrometry of selected m/z ratios identified several compounds in rat urine and characterized various chemical families, including carboxylic acids, amines, sulfated compounds, glucuronides and glycosides, by the observation of characteristic fragment ions or neutral losses. The method has been applied to the investigation of the chronic toxicity of heavy metals in rat urine. A few tens of m/z ratios, differing in intensity more than threefold from control values, were observed in both positive and negative modes. The time variations for some selected ions suggest that LC/ESI-MS could allow selective characterization of biomarkers in response to specific toxic compounds. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Atmospheric pressure chemical ionisation reversed-phase liquid chromatography/ion trap mass spectrometry of intact bacteriohopanepolyols

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2003
    Helen M. Talbot
    Atmospheric pressure chemical ionisation liquid chromatography/multi-stage ion trap mass spectrometry (APCI-LC/MSn) has been applied to the study of intact bacteriohopanepolyols. Spectral characterisation of bacteriohopanepolyols of known structure present in bacterial extracts (Zymomonas mobilis and a fermenter containing methanotrophs including Methylococcus capsulatus) has revealed greater structural detail than previous liquid chromatography/mass spectrometry (LC/MS) methods and identified characteristic fragmentations indicative of numerous biohopanoid structures. Analysis of a Recent sedimentary extract from Lake Druzhby (Antarctica) has demonstrated the power of this technique to detect biohopanoids in complex samples including at least partial characterisation of previously unknown composite structures. Copyright © 2003 John Wiley & Sons, Ltd. [source]