The document stipulates the use of Gas chromatography, CG to determine the purity of industrial propylene and hydrocarbon impurities, including methane, ethane, ethylene, propane, cyclopropane, isobutane, n-butane, propane, acetylene, trans-2-butene, 1-butene, isobutene, cis-2-butene, 1,3-butadiene, methylacetylene, etc. It is suitable for the determination of industrial propylene with a purity greater than 98% (volume fraction) and a hydrocarbon impurity content of not less than 1 mL/m2. The document warns users to have practical experience in formal laboratory work and to be responsible for taking appropriate safety and health measures to ensure compliance with relevant national regulations. The document cites several normative documents, such as the determination of trace hydrogen in industrial ethylene and propylene, the determination of trace carbon oxide, carbon dioxide and acetylene in industrial ethylene and propylene, etc. In the principle section, the document introduces the calibration area normalization method and the External standard method, which are used to determine the content of each impurity component, respectively, and to deal with the determination results of impurities such as hydrogen, oxygen, carbon oxide, carbon dioxide, water, oligomers and oxygenated compounds. The document does not define terms and definitions.