Mass spectrometric characterization of some human metabolites of flumecinol

The mass spectrometric behaviour of six human metabolites formed by hydroxylation in various positions of the alpha-ethyl group or/and on the phenyl ring of 3-trifluoromethyl-alpha-ethyl-benzyhydrol (flumecinol) and seven related compounds has been studied. The electron impact mass (EI) spectra of these compounds show significant and characteristic effects of substituents, but many of them suffer from weakness or even from absence of the M+. peak owing to the very facile primary loss of the alpha-aliphatic chain, i.e. no direct information can be obtained about the size of the molecule and that of this chain. It is demonstrated for derivatives possessing a hydroxylated alpha-ethyl group that the difficulties in structural characterization due to the lack or weakness of M+. and [M + H]+ peaks in their EI and chemical ionization mass spectra, respectively, can be overcome by studying their silyated or boronated derivatives. Furthermore, silyation enables us to obtain a clear base for distinction of the primary and secondary alcohols of this type.