This standard uses Gas chromatography, CG to determine the purity and specific impurities of benzene in cyclohexane feedstocks. It is suitable for benzene with a purity of 99% to 100%, and can detect various impurities such as toluene, methyl cyclopentane, etc. The standard emphasizes that absolute purity is difficult to determine and is mainly used for final product inspection and process control. Test results should be rounded according to Practice E29 and expressed in SI units.