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