What does Mass Spectrometry Do?

Mass spectrometry (or MS) is a way to measure the mass of individual molecules, fragments of molecules or individual atoms. The mass of these tiny particles is microscopic. A molecule of water, for example, weighs about 10^-22 grams (i.e., 0.0000000000000000000001 g)! It does this by sepatating ionised molecules according to the ratio of the their mass to their charge.