Determination of polyisocyanates in occupational environments

The main focus of this dissertation is determination of polyisocyanates in workplace environments. This dissertation is comprised of four manuscripts.; The first paper discusses two major issues with polyisocyanates in occupational environments: the exposure metric and the standards. Based on isocyanate bulk analysis and a detailed documentation of problems with current bulk mass metric it was concluded that isocyanate exposure should be standardized on the total NCO content of the sample. With regard to regulations, current standards were compared and advantages and limitations were discussed. Based on a comprehensive review of the toxicological literature and for other pragmatic reasons, the paper suggests promulgation of a universal NCO-based polyisocyanate standard separate from the monomers.; The second paper evaluated the performance of the NIOSH draft method 5525 for analysis of aliphatic isocyanates in auto body repair shops. The method uses 1-(9-anthracenylmethyl)piperazine (MAP) as the derivatizing reagent. The study concluded that the MAP method offers some significant advantages to other methods, such as enhanced resolution, increased sensitivity and selectivity, ability to measure the total NCO content of the sample, and a constant ultraviolet response of the MAP-isocyanate derivatives, regardless of their origin. For these reasons the MAP method should become the standard isocyanate method of its class.; The third paper investigated the ability of MAP-impregnated filters for sampling of aliphatic HDI-based isocyanates in a side-by-side field comparison with impingers. It was concluded that MAP-impregnated filters could be successfully used for sampling of aliphatic isocyanates.; The fourth paper reports on the development of a new analytical method for polyisocyanates, using 1,8-diamononaphthalene (DAN) as the derivatizing reagent. The DAN method works on a novel principle. The method quantifies perimidone, a single analyte, which is a measure of the total NCO content of a sample. The draft method developed worked very well with the class of aromatic isocyanates, and aliphatic monoisocyanates and diisocyanates, but not with aliphatic polyisocyanates. Further method development and validation is required.