Liquid chromatography mass spectrometry common metabolites

High-performance liquid chromatography-mass spectrometry (HPLC-MS) is a powerful analytical technique widely used in recent years for the analysis of biomarkers and metabolites. Biomarker determination and quantification, whether metabolic or adducted biomolecules, are commonly used to evaluate exposure and support biomonitoring research, especially in the area of occupational exposure and health. Some of the common problems and strategies of HPLC-MS biomarker analysis involve matrix effects, the use of isotope-labeled internal standard compounds, and sample cleanup usually all of these factors must be evaluated within the development phase of an analysis procedure. Specific examples of biomarker analysis using HPLC-MS include acrylamide, aromatic compounds, and 1-bromopropane, and these examples are discussed in detail. 

Valaskovic, G. A. Utley, L. Lee, M. S. Wu, J.-T. Ultra-low flow nanospray for the normalization of conventional liquid chromatography/mass spectrometry through equimolar response Standard-free quantitative estimation of metabolite levels in drug discovery. Rapid Common. Mass Spectrom. 2006, 20(7), 1087-1096. 

More sensitive and specific techniques, using gas chromatography (GC) or GC-mass spectrometry, are able to identify very low concentrations of ecstasy in any type of specimen, and may also differentiate it from closely related drugs (MDA, MDEA) or other commonly abused stimulant drugs. More sophisticated GG-mass spectrometric or liquid chromatographic-mass spectrometric methods are now available to resolve the different isomers (R S) of ecstasy and their metabolites. 

Sams M, Strutt P, Barnes K, et al.. Determination of dimetridazole, ronidazole and their common metabolite in poultry muscle and eggs by high performance liquid chromatography with UV detection and confirmatory analysis by atmospheric pressure chemical ionisation mass spectrometry. Analyst 1998 123 2545 -2549. 

Liquid chromatography is routinely used for the quantitative analysis of a drug and its metabolites in radiolabeled in vitro metabolism experiments and in humans and animal ADME studies. Online radio-flow detection (RFD) and offline microplate scintillation counting (MSC) are the most commonly used radiochromatographic techniques in radiolabeled metabolite profiling and quantification (Boernsen et al., 2000 Nassar et ah, 2003 Bruin et al., 2006). LC/RFD is compatible with ESI mass spectrometry and provides high analytical speed and excellent separation resolution (Athersuch et al., 2008). 

Rousu, T, Pelkonen, O., Tolonen, A. (2009) Rapid Detection and Characterization of Reactive Drug Metabolites In Vitro Using Several Isotope-labeled Trapping Agents and Ultra-performance Liquid Chromatography/Time-of-flight Mass Spectrometry. Rapid Common. Mass Spectrom. 23 843-855. 

This LC-MS experimental approaches used in NEF metabolite identification are also routinely employed for in vitro metabolism comparisons across species, in which liver microsomes or hepatocytes from humans and animal species are used. In addition, liver microsomal incubations followed by metabolite identification and quantitative estimation using liquid chromatography-ultraviolet/ mass spectrometry (LC-UV/MS) is an approach commonly taken to determine metabolic soft spots, where a major metabolic reaction takes place (Table 6.10). Use of UV detection allows for quantitative analysis of major metabolites in the absence of chemical standards, with the assumption that the metabolic reaction did not disturb the molecule s UV chromophore. 

Haloperidol (Haldol), risperidone (Risperdal), loxapine (Loxitane), ziprasidone (Geodon), quetiapine (Seroquel), clozapine (Clozaril), aripiprazole (Abilify), and thioridazine (Mellaril) are targeted in this solid phase extraction (SPE), liquid chromatography— tandem mass spectrometry (LC-MS/MS) method. Both 9-hydroxy-risperidone (Paliperiodone), an equipotent metabolite, and mesoridazine (Serentil) are also included in this method as they are pharmacologically active major metabolites of risperidone and thioridazine, respectively (4). Olanzapine (Zyprexa) can be quantified with this instrument method however, the extraction method is a liquid-liquid basic extraction (see Note 1). Due to the subsequent administration of antidepressants in conjunction with antipsychot-ics, this method can also be used for many of the common antidepressants, including the selective serotonin reuptake inhibitors (SSRIs) (see Note 2). 

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