Metabolite identification coupled with tandem mass

Urpi-Sarda M, Jauregui O, Lamuela-Raventos RM, Jaeger W, Miksits M, Covas MI and Andres-Lacueva C. 2005. Uptake of diet resveratrol into the human low-density lipoprotein. Identification and quantification of resveratrol metabolites by liquid chromatography coupled with tandem mass spectrometry. Anal Chem 77(10) 3149—3155. 

Superior sensitivity, efficiency, and specificity have made high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS), the predominant analytical technique for characterization and quantitative analysis of metabolites (Kostiainen et al., 2003 Ma et al., 2006 Prakash et al., 2007). Ion trap, triple-quadrupole, and quadmpole time-of-flight (Q-TOF) mass spectrometers are routinely used to profile and characterize metabolites in plasma and excreta (Ma et al., 2006). The combination of scan types and features available on mass spectrometers of different design (product ion, MS", neutral loss, precursor ion scans, accurate mass measurements) allows identification and characterization of putative and unexpected metabolites with or without little prior knowledge of biotransformation pathways of a given dmg molecule. 

Nassar, A. E. (2003). Online hydrogen-deuterium exchange and a tandem-quadrupole time-of-flight mass spectrometer coupled with liquid chromatography for metabolite identification in drug metabolism. J. Chromatogr. Sci. 41 398-404. 

Liquid chromatography-ionspray-mass spectrometry has been shown to be an attractive approach for the determination of semduramicin in chicken liver. Tandem MS using the CID of the molecular ions further enhanced the specificity providing strucmre elucidation and selective detection down to 30 ppb. Liquid chromatography-ionspray-mass spectrometry has also been successfully applied for the assay of 21 sulfonamides in salmon flesh. Coupling of LC with either ISP-MS or ISP-MS-MS has also been investigated as an attractive alternative for the determination of erythromycin A and its metabolites in salmon tissue. The combination of these methods permitted the identification of a number of degradation products and metabolites of erythromycin at the 10-50 ppb level. Tandem MS with CID has also been... 

The detection and quantitation of adducts produced by the in vitro formation of reactive metabolites was also demonstrated by UHPLC coupled to inductively coupled plasma (ICP) MS and QqTOF/MS. The identification of reactive metabolites is of great interest as they may be involved in the idiosyncratic dmg reactions that lead to many dmgs being withdrawn from the market. In a recent study, adducts formed from clozapine in the human liver by microsomes supplemented with glutathione (GSH, used as a nucleophile to trap reactive electrophilic metabolites) were determined by UHPLC-MS (62). The adducts were quantified by sulfur-specific ICP-MS and further identified by QqTOF/MS. The use of ICP-MS offers a novel, rapid, and sensitive way to determine the quantity of GSH adducts with reactive drug metabolites formed in the liver. When used in tandem with QqTOF/MS, this technique features the possibility to assign a mass to the sulfur response, which allows for a tentative deduction of the GSH adduct structure. 

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