Abstract
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 (HSO3NH2) 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.