Description:
<jats:title>Abstract</jats:title><jats:p>The fragmentations under electron impact of 5‐phenyl‐1,4‐benzodiazepin‐2‐ones are investigated with the aid of high resolution, metastable decompositions and deuterium labeling. Based on our data a mechanism for the formation of the [M – H]<jats:sup>+</jats:sup> ion is proposed. It is shown that the [M – CHO]<jats:sup>+</jats:sup> ion is probably formed by two different pathways. Data on two minor fragment ions give support to the structure proposed for the [M – CHO]<jats:sup>+</jats:sup> ion.</jats:p>