Identification of Glue Vapors Using Electron Impact and Chemical Ionization Modes in GC–MS

Abstract

The analysis of the vapors from six commercial glues provided an interesting and challenging lab assignment for students in an instrumental analysis laboratory course. Students used both electron impact (EI) and chemical ionization (CI) modes of operation in GC–MS to identify the volatile components in their assigned glue. Chemical ionization using methane as the reagent gas provided a complementary analysis to the more common EI mode of operation. In the softer CI mode, there is a higher probability of observing the molecular ion. Students were required to explain the observation of specific mass fragments observed from both EI and CI operations in terms of their reactions in the ion source of the mass spectrometer. This interpretation of mass spectra provided the students an educational exercise for understanding the ionization processes that occur in mass spectroscopy.