This method is for determining trace hydrocarbon impurities inhigh purity p-xylene. The lower limit of detection for any singlecomponent is 0.002 mass %. The method can also be used fordetermining the total purity of the p-xylene. Mixed xylene isomersand/or diethylbenzenes in other process streams should bedetermined using UOP Method 744, Aromatics in Hydrocarbons by GasChromatography.