Abstract
A collection device for distinguishing between vapor and aerosol, appropriate for use in personal sampling, has been developed and evaluated. This two-stage sampler relies on the differential diffusion rate of vapor and particles in air to separate them into two identifiable fractions. Vapors are removed in the first stage, which is a hollow tube with inside walls coated with a trapping medium; particulates are trapped after they pass through the tube. By appropriate choice of sampling flow rate, tube diameter and tube length, airborne material can be separated into vapor and aerosol fractions. This sampler is practical for monitoring worker exposure and for inhalation studies where it is desirable to monitor the mode of exposure as well as the concentration. A sampler was developed and tested specifically for aromatic amines using acidified silica gel coated on the inner tube wall of the vapor collector followed by an acidified filter for aerosol collection. The vapor collection efficiency of the sampler was demonstrated with laboratory-generated test atmospheres of aniline vapor. Variations in sampler tube length and diameter, sampling flow rate, and sampling time were studied to determine optimum collection efficiency and capacity. Test atmospheres of iron oxide fume were used to test the partitioning of aerosol in the sampler. The vapor and aerosol partitioning of airborne m-phenylenediamine (MPDA) and methylenedianiline (MDA) was investigated at various concentrations.