Liquid chromatography-thermospray tandem mass spectrometry for identification of a heptabarbital metabolite and sample work-up artefacts.
An unknown heptabarbital metabolite, observed in the liquid chromatogram of rat plasma and urine samples after administration of heptabarbital, was identified by liquid chromatography-thermospray tandem mass spectrometry. By applying the parent scan mode for screening and the daughter scan mode for structure elucidation, the metabolite was determined to be 5-ethyl-5-(1'-, 3'- or 6'-cycloheptadienyl)barbituric acid. It was demonstrated that artefact formation occurred when hydrochloric acid was used for conjugate hydrolysis in the sample clean-up. Identification of the artefacts was achieved by the same method. Confirmation of the structures of the metabolite and the artefacts was obtained by gas chromatography-electron impact mass spectrometry.
Division of Analytical Chemistry, University of Leiden, Netherlands.
C E
CE
Heeremans
A M
AM
Stijnen
R A
RA
van der Hoeven
W M
WM
Niessen
M
M
Danhof
J
J
van der Greef
D000818:Animals; D001463:Barbiturates / Q000097:blood / Q000737:chemistry / Q000652:urine*; D002853:Chromatography, Liquid / Q000379:methods*; D005189:False Positive Reactions; D008401:Gas Chromatography-Mass Spectrometry; D006851:Hydrochloric Acid; D013058:Mass Spectrometry / Q000379:methods*; D051381:Rats
D001463:Barbiturates; D006851:Hydrochloric Acid