Interpretation of Mass Spectra

In mass spectrometry (MS), the obvious concern is the actual masses of the atoms, molecules, or fragment thereof. Using MS techniques to measure the ratio of 12 C to 14 C, one can determine the age of objects that incorporated 14 C into their structure such as once living fossils. Isotopes hold a special place not only in MS but also, in general terms, in chemistry and physics. The reason for this lies in the fact that isotopes have the same atomic number Z, and therefore are different versions of the same atom. As a consequence of the existence of isotopes, several different concepts of mass are routinely used in MS, such as average mass, nominal mass, monoisotopic mass, and exact mass. Since MS is all about measuring the nuclear mass, it takes full advantage of this natural phenomenon to get a plethora of information extremely valuable when doing MS analysis and interpretation of results.