In order to improve the purity of the carrier gas, it is necessary to remove some impurities, such as   organic matter, trace oxygen, water in the carrier gas. Impure carrier gas can lead to column failure, the sample changes. Hydrogen flame chromatograph can increase the noise of the base flow and thermal conductivity chromatography can make chromatographic linearity become inferior, so the carrier gas must be purified. Generally, we use chemical treatment methods to remove oxygen, such as removing oxygen with the activated copper, removing organic impurities with molecular sieve and activated carbon as well as removing water with   silicone and molecular sieve.