Question

How would you expect the EI and CI mass spectra of stearyl amine (MW=269) to differ? If the CI mass spectrum is collected using methane as a reagent gas, would you expect to see any peaks in the spectrum at m/z > 269? Explain.

Answer 1

EI mode of mass spectra bombards high energy electron beam and records the results of electron empact as a spectrum of positive ions seperation on the basis of mass/charge (M/Z). Due to high energy beam the molecule get fragmented.

but in CI technique chemical ionization happens on lower energy process than electron ionization (EI). The lower energy yields less or sometimes no fragmentation. and for sometime it gives usually a simpler spectrum.

here in case of stearyl amine it can form adduct with methane due high electronegativity of nitrogen and this is tha reasion where it can give an extra peack greater than 269.