Routine Determination of Benzene, Toluene, Ethylbenzene and Total Aromatics in Hydrocarbon Solvents by a Combination of Liquid and Gas Chromatography

An analytical procedure is presented which determines benzene, toluene, ethylbenzene and total aromatics in non-olefinic hydrocarbon solvents which boil between 100 and 450°F. This compositional information is required in connection with current air pollution laws. The method is based on (a) the addition of a known amount of internal standard (hexamethylbenzene), (b) segregation of the aromatic hydrocarbons in the sample by liquid chromatography on silica, and (c) analysis of this aromatic hydrocarbon fraction (plus solvent) by gas chromatography. The method is applicable to samples containing 0.1% or more total aromatics, with an estimated precision of ±3% relative and an accuracy of ±5% relative. Analysis cost per sample is 1½ to 2½ man hours, depending upon the number of samples run simultaneously.