GC/MS stands for Gas Chromatograph Mass Spectrometry. GC/MS is the gold standard test that proves an essential oil is 100% pure and therapeutic grade with no synthetics or other additives. A GC/MS test separates an essential oil into individual components for analysis. The oil is vaporized upon entry into the device, and the oil passes through a column assisted by a carrier gas, usually helium or hydrogen. The column itself sits within an oven where change in heat over time is measured. Different chemical compounds react at different speeds within the column, and this information is captured on the Gas Chromatograph Mass Spectrometry.