title: A simple method for differentiation of monoisotopic drug metabolites with hydrogen-deuterium exchange liquid chromatography/electrospray mass spectrometry.
abstract: A simple but efficient method for determination of labile protons in drug metabolites using post-column infusion of deuterium oxide (D2O) in liquid chromatography/mass spectrometry (LC/MS) experiments with electrospray ionization and time-of-flight mass spectrometry is described. The number of exchangeable protons in analytes, i.e. hydroxyl, amine, thiol and carboxylic acid protons, can easily be determined by comparing the increase in m/z values after H/D-exchange occurring online between a HPLC column and electrospray ion source. Especially, the hydroxyl metabolites and S/N-oxides with the same accurate mass can be distinguished. A good degree of exchange was obtained in repeatable experiments. Only a low consumption of D2O is needed in a very easy and rapidly set-up procedure. The method is applied in the study of metabolites of omeprazole and imipramine in human and mouse in vitro samples, respectively, together with exact mass data obtained from time-of-flight mass spectrometric experiments.
authors.affiliation: Novamass Analytical Ltd., P.O. Box 3000, 90014 Oulu, Finland. ari.tolonen@novamass.net
authors.forename: Ari
authors.initials: A
authors.lastname: Tolonen
authors.forename: Miia
authors.initials: M
authors.lastname: Turpeinen
authors.forename: Jouko
authors.initials: J
authors.lastname: Uusitalo
authors.forename: Olavi
authors.initials: O
authors.lastname: Pelkonen
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003903:Deuterium / Q000378:metabolism*; D006801:Humans; D007099:Imipramine / Q000493:pharmacokinetics*; D008099:Liver / Q000378:metabolism*; D013058:Mass Spectrometry; D009853:Omeprazole / Q000493:pharmacokinetics*
chemical_list: D003903:Deuterium; D009853:Omeprazole; D007099:Imipramine