title: Evaluation of liquid chromatography coupled with high-field 1H NMR spectroscopy for drug metabolite detection and characterization: the identification of paracetamol metabolites in urine and bile.
abstract: The applicability of coupled reversed-phase high performance liquid chromatography (HPLC)-NMR spectroscopy for the detection and identification of paracetamol (N-(4-hydroxyphenyl)acetamide) and its sulfate, glucuronide and N-acetylcysteinyl metabolites in the unprocessed biological fluids, human urine, rat urine and rat bile, is investigated. Analysis of these samples was performed by gradient HPLC elution and directly coupled 500 MHz 1H NMR spectroscopy detection using a combination of one- and two-dimensional NMR methods in stopped-flow mode. The stopped-flow approach is demonstrated to be an efficient technique for identification of drug metabolites which have, for example, a UV-chromophore. Stopped-flow HPLC analysis with NMR detection is a viable technique and halting the chromatographic process several times during a run has a negligible effect on the separation and NMR characterization. The post-acquisition data processing method of 'quantified maximum entropy' is shown to provide a means of improving the quality of spectra for minor components, thus aiding NMR resonance assignments.
authors.affiliation: Bruker Analytische Messtechnik GmbH, Rheinstetten, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Spraul
authors.forename: M
authors.initials: M
authors.lastname: Hofmann
authors.forename: J C
authors.initials: JC
authors.lastname: Lindon
authors.forename: R D
authors.initials: RD
authors.lastname: Farrant
authors.forename: M J
authors.initials: MJ
authors.lastname: Seddon
authors.forename: J K
authors.initials: JK
authors.lastname: Nicholson
authors.forename: I D
authors.initials: ID
authors.lastname: Wilson
mesh_terms: D000082:Acetaminophen / Q000032:analysis / Q000378:metabolism* / Q000652:urine; D000818:Animals; D001646:Bile / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002853:Chromatography, Liquid / Q000379:methods; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D051381:Rats
chemical_list: D000082:Acetaminophen