Douglas O. Johns

Project title: The Effect of Varing Concentrations of Chemical Mictures Containing Toluene and Methyl Isobutyl Ketone on the Accuracy of Collection in Passive and Active Samlplers

Degree: MS | Program: Industrial Hygiene (IH) | Project type: Thesis/Dissertation
Completed in: 2000 | Faculty advisor: Michael S Morgan


Hazardous vapors and gases are commonly present in a wide range of industries throughout the world. In order to protect workers from these contaminants, it is important to be able to accurately determine the concentrations of gases and vapors in the workplace. Traditionally, sampling has been performed by drawing air through a sorbent tube with a pump. Passive samplers were developed in the 1970's an alternative to active sampling. Passive samplers do not require a pump, but rather work on the principle of diffusion of molecules in air. Several studies have shown that passive samplers give similar results to those obtained using active sampling. However, few studies have assessed the effect on the accuracy of a passive sampler when an interfering compound is present. Furthermore, most of the studies that have been done have used the active sampler as a gold standard or reference. In this study, 15 mixtures of methyl isobutyl ketone (MIBK), a polar compound, and toluene, a non-polar compound, were created and sampled using an active charcoal sampler and two types of passive samplers. Varying concentrations of one compound were used, while the concentration of the other compound was held constant. A MIRAN infrared analyzer was used to determine the actual concentration of the mixtures created. It was shown that at low concentrations of MIBK (20 and 40 ppm), toluene had a significant interfering effect on all three sampler types. No interfering effect of MIBK on toluene sampling was seen for any of the samplers.