How does mass spectrometry testing work?

In addition to gas chromatography, essential oil samples also are tested for composition using mass spectrometry. In mass spectrometry, samples are vaporised and then ionised and each individual compound in a sample is measured by weight. Mass spectrometry provides additional insight to the purity of an essential oil by revealing the presence of non-aromatic compounds, such as heavy metals or other pollutants, which are too heavy to elute along a gas chromatograph. The combination of gas chromatography and mass spectrometry is sometimes referred to as a GC/MS test.