This method is for determining trace impurities in distilled, high purity cumene by gas chromatography (GC). Benzene and toluene may not be separated from the non-aromatic impurities by this method but, if required, may be determined individually by UOP Method 543. Isoparaffins and/or olefins in the C12 range may interfere with the determination of ethylbenzene. The lower limit of detection for any single component is 5 mg/kg (mass-ppm).