The sample is injected into the gas chromatograph, enters a gas stream which will transport the sample into a separation tube which known as Column. Usually, an inert gas such as helium or an unreactive gas such as nitrogen is used as a carrier gas. Various components are separated inside the column. The detector measures amount or quantity of the components that exit the column at a different time (retention time). In order to analyze the sample with an unknown concentration, a standard sample with known concentration is injected into the gas chromatograph. The retention time and area of standard sample peak are compared to the test sample to calculate its concentration.