Evaluation of the feasibility of preparing a reference material: Active charcoal tubes charged with benzene, toluene and m-xylene.

Volatile organic compounds in air are mostly determined after enrichment by adsorption on active charcoal. A batch of three hundred active charcoal tubes was charged with benzene, toluene and m-xylene by drawing a volume of air with known composition through the tubes in such a manner as to charge each tube of the batch with exactly the same amounts. From this batch every tenth tube was analyzed gas-chromatographically. Further 60 charged tubes were stored under different conditions and analyzed within one year. It appeared that the charging was homogeneous and that no significant alteration was found within one year