Report on a modified charcoal sampling tube used by the National Institute of Occupational Safety and Health, Cincinnati, Ohio, for the collection and concentration of solvent vapors, to meet the requirements for a personal sampler. The packing size and configuration of the modified tube assure that the pressure drop across the tube will not exceed one inch of mercury (7439976) when sampling is accomplished at a flow rate of one liter per minute. This feature allows battery operated pumps to be used thus providing the advantage of complete portability necessary in personal type sampling. The modified tube is also useful for atmospheric sampling of mercury vapor exposures and has potential use in sampling for contaminants other than solvent vapors and mercury vapor. This item is the final page of the PDF associated with this article.