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Analysis of di‐n‐butylphthalate biotransformation in cattle by liquid chromatography/ion trap mass spectrometry/mass spectrometry
Author(s) -
Coldham N. G.,
Dave M.,
Sauer M. J.
Publication year - 1998
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/(sici)1096-9888(199809)33:9<803::aid-jms689>3.0.co;2-0
Subject(s) - chemistry , metabolite , chromatography , mass spectrometry , biotransformation , phthalic acid , ion trap , chemical ionization , ion , ionization , biochemistry , organic chemistry , enzyme
The nature of products of contamination intake were investigated in cattle dosed with [ 14 C]di‐n‐butylphthalate (DBP). Radio‐labelled metabolites were extracted from bile, faeces, plasma and urine onto solid‐phase media, fractionated by ion‐exchange chromatography, separated by reverse phase HPLC and analysed by negative ion atmospheric pressure chemical ionization mass spectrometry n (LCQ, Finnigan). All matrices contained a common major metabolite [deprotonated molecular ion (M‐H) ‐ m / z 221] which coeluted with and had an identical daughter ion spectrum to reference monobutylphthalate (MBP). MBP was metabolised to a β‐glucuronidase sensitive compound (M‐H) ‐ m / z 397 whose spectrum contained daughter ions ( m / z 175 and 221) consistent with the parent glucuronide. A further three β‐glucuronidase resistant radio‐labelled metabolites were also produced (M‐H ‐ m / z 165, 193 and 237); comparison of daughter ion spectra with those of reference MBP and phthalic acid indicated identity with phthalic acid, monoethylphthalate (MEP) and monohydroxybutylphthalate (MHBP) respectively. The presence of a benzoate daughter ion ( m / z 121) in all spectra was indicative of side chain biotransformation. Both MBP and MEP contained a phthalate daughter ion ( m / z 165) indicating loss of a butyl and ethyl side chain respectively. A daughter ion of m / z 89 derived from the side chain provided evidence that the third metabolite was MHBP. Incubation of DBP with isolated bovine hepatocytes produced the same metabolites and provided relatively clean samples for LC/MS n analysis. Detection of these DBP metabolites in meat or dairy food products will provide evidence for environmental exposure and biotransformation in vivo , whereas the presence of the parent compound would suggest contamination during food processing and packaging. © Crown Copyright 1998. Reproduced with the permission of the Controller of Her Majesty’s Stationery Office.