Lubricants (OT)

Mass spectrometry works - in this instance - by looking at the individual m olecules making up the lines in the finger-print.

In principle it only gives the molecular weight of the molecule, but more c omplicated mass spectrometers can do that very exactly, so sometimes you ca n identify which atoms make up the molecule, and sometimes you can break up the primary ions and look at the fragments the original molecule broke up into, which can be even more informative.