Characterization of the antihistamines tripelennamine, methapyrilene, and thenyldiamine and their N-oxides by thermospray mass spectrometry.

This study describes an investigation of the thermospray (TS) mass spectrometric analysis of tripelennamine, methapyrilene, thenyldiamine, and their N-oxide derivatives. These compounds were analyzed by direct injection TS mass spectrometry in the column bypass mode and with 0.1M ammonium acetate/methanol (80:20, v/v) as the mobile phase. Typically, the parent antihistamines produced only [MH]s ions under these conditions. The N-oxides provided strong [MH]s ions and multiple fragment ions. A scheme to explain the fragmentation patterns is proposed.