The goal of Gas chromatography is to determine, separate, and measure every chemical component in essential oil samples. This machine (gas chromatograph), heats the oil and then pushes it through an enclosed column of a passive gas such as hydrogen, helium or nitrogen. The individual oil compounds travel through the column at different speeds due to their molecular weights. A detector at the column’s end measures the passage time of each component. A chromatogram is a report showing a graph that shows the separation of the detector reaction (on the y-axis) and the retention time. Scientists compare the chromatogram’s peak with established standards to verify that the right chemical constituents were present in the right amounts.