Mass spectrometry

The technique measures the mass-to-charge ratio of ions. The first step is to ionize the sample (for example by bombarding it with electrons) and then send it through an electric field. The mass/charge can be measured by the deflection generated by the electric field.

Mass spectrometry is traditionally coupled with separation methods, such as HPLC (I assume the rationale is to get a cleaner sample and thus a cleaner result).