This standard describes the use of Gas chromatography, CG to analyze the effective carbon number of cyclohexane, suitable for setting the specification of cyclohexane and quality control during production. This method can be used to detect common impurities in cyclohexane with a detection limit of 1 mg/kg. Although this method can analyze impurities in the range of 1 to 400 mg/kg, it may not be detectable for extremely high boiling points or abnormal impurities. Test results are subject to rounding rules and are expressed in SI units.