Mass spectrometry of the trimethylsilyl derivatives of medicinal barbiturates

The electron ionization mass spectra of the trimethylsilyl derivatives of a number of medicinal barbiturates have been examined. The trimethylsilyl derivatives are useful in the identification of barbiturates by gas liquid chromatography/mass spectrometry (g.l.c.‐m.s.). Mass spectra of these derivatives are characterized by abundant high mass ions which permit the ready distinction of one barbiturate from another. The prominent and characteristic [M ‐ 15] ion is an effective monitor of molecular weight, while other unique fragmentations and/or varying patterns of relative abundance serve to differentiate isomers.