A diffusive sampler for personal monitoring of toluene diisocyanate (TDI) exposure; Part II: Laboratory and field evaluation of the dosimeter.

A passive monitor for TDI which utilizes microporous Teflon diffusion membranes and a 0.5% sulfuric acid (H2SO4) absorbing medium was evaluated. The collection rate of TDI is proportional to exposure dose from 10 to at least 300 ppb.hr, and response is equivalent for 2,4- and 2,6-TDI. Collection rate is independent of humidity and normal atmospheric pressure variations, while temperature causes a decrease of 1.0% per degree centigrade. Negative interference caused by ambient nitrogen dioxide (NO2) is eliminated by addition of sulfamic acid (HSO3 NH2) to the collecting medium. N-ethylmorpholine is a positive interferent. Field testing of the sampler against a reference impinger technique indicated a positive bias when TDI is aerosolized.