Investigation of some pentasubstituted 1,4‐dihydropyridines by means of fast ion bombardment, chemical ionization and electron impact mass spectrometry

Abstract

AbstractPositive fast ion bombardment, positive chemical ionization (CI+) and positive electron impact (EI) ionization mass spectrometry were used to investigate a number of relatively large and structurally related organic molecules. Some of the major dissociation pathways observed in the CH4‐CI+ mass spectra are not present under NH3‐CI+ conditions, but are obtained in the collision‐induced dissociation (CID) spectrum of the 50 eV MH+ molecular ion, formed in the latter reaction. The resemblance between the EI mass spectra and their fast ion bombardment counterparts, the effect of changing the energy of the bombarding Cs+ ion beam over the range 2–16 keV and the different degrees of internal excitation of ions formed in different CI reagent gases are discussed.