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Determination of n ‐hexane metabolites by liquid chromatography/mass spectrometry 2. Glucuronide‐conjugated metabolites in untreated urine samples by electrospray ionization
Author(s) -
Manini Paola,
Andreoli Roberta,
Mutti Antonio,
Bergamaschi Enrico,
Niessen Wilfried M. A.
Publication year - 1998
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/(sici)1097-0231(19981115)12:21<1615::aid-rcm372>3.0.co;2-m
Subject(s) - chemistry , chromatography , mass spectrometry , glucuronide , electrospray ionization , atmospheric pressure chemical ionization , hexane , liquid chromatography–mass spectrometry , tandem mass spectrometry , electrospray , chemical ionization , metabolite , gas chromatography–mass spectrometry , formic acid , ionization , ion , organic chemistry , biochemistry
A liquid chromatography atmospheric pressure electrospray mass spectrometry (ESI‐LC/MS) system was evaluated for the identification and characterization of n ‐hexane conjugated metabolites (glucuronides) in untreated urine samples. Chromatography of glucuronides was obtained under ion‐suppressed reversed‐phase conditions, by using high‐speed (3 cm, 3 μm) columns and formic acid (2 m M ) as modifier in the mobile phase. The mass spectrometer was operated in negative ion (NI) mode. For the first time, four glucuronides were identified by ESI‐LC/MS in untreated urine samples of rats exposed to n ‐hexane: 2‐hexanol‐glucuronide, 5‐hydroxy‐2‐hexanone‐glucuronide, 2,5‐hexanediol‐glucuronide and 4,5‐dihydroxy‐2‐hexanone‐glucuronide. Confirmation of the conjugated metabolites was obtained by LC/MS/MS experiments. Gas chromatography/mass spectrometry (GC/MS) and atmospheric pressure chemical ionization (APCI) LC/MS analyses were performed on the same samples. An integrated approach GC/MS‐LC/MS for the semi‐quantitative analysis of n ‐hexane glucuronides, whose standards are not commercially available, is discussed and proposed here. In order to understand the fate of the metabolites during sample pre‐treatment, a study about the effects of enzymatic and acid hydrolysis on urine samples was conducted on glucuronides isolated by solid‐phase extraction. Combined analyses by GC/MS and LC/MS enabled us to distinguish ‘true’ n ‐hexane metabolites from compounds resulting from sample treatment and handling (i.e. enzymatic and acid hydrolysis, extraction and GC injection). © 1998 John Wiley & Sons, Ltd.