This method is for determining trace impurities in high-puritymixed xylenes by gas chromatography (GC). Specific trace impuritiesdetermined include non-aromatic hydrocarbons, benzene, toluene andindividual C9 and C10 aromatic compounds. C10 or highernon-aromatics, if present, may interfere with the determination ofbenzene, but it can be determined by UOP Method 543. The lowerlimit of quantitation for any single component is 1 mg/kg(mass-ppm). Impurities at concentrations above 500 mg/kg should bedetermined by UOP Method 744.