What are the differences between mass spectrometry and FTIR?
Spectrometry, yes. They’re physically different phenomena that are being measured. Mass spectrometry, as it says, measures the distribution of mass, like how many particles of atomic weight four you have, versus atomic weight twelve. From that, you can tell what nuclei you’ve measured. This gives you an elemental analysis of your unknown, or your mixture, whatever it happens to be, but not its chemical composition.