The hazards of isocyanate in the workplace have been well documented. Workers who are involved in the production of polyurethane foams, elastomers and fibers as well as in the application of polyurethane paints and coatings are all exposed to diisocyanate and polyisocyanates. The vapor can irritate the nose, throat and lungs, and eventually lead to pulmonary dysfunction and bronchial pneumonia. Chronic exposure can lead to sensitization in 2-5% of the population. Isocyanate aerosol can irritate the eyes, and contact with the skin can cause severe blistering and swelling. The primary goal of this research was to develop a convenient, accurate, and sensitive sampling and analysis procedure for hexamethylene diisocyanate (HDI) monomer and HDI oligomer in the spray-painting environment. This goal was achieved through a multi-faceted research effort: (1) New cassette samplers were developed which feature a polyurethane foam (PUF) plug positioned on top of a fiberglass filter. These samplers do not spill and therefore are more convenient for use in the field. In a series of side-by-side sampling events, an impinger filled with MOP in toluene was compared directly with a cassette sampler containing a PUF sponge impregnated with MOP or MAP in dimethylsulfoxide (DMSO). For the analysis of HDI oligomer there is no significant difference (p< 0.05, n= 7) in the air concentration when using either sampler. (2) The derivatizing reagent, tryptamine, which has a more uniform response toward all isocyanates, was evaluated during spray-painting operations. The analytical results indicate that there is no significant difference (p< 0.05, n= 5) when comparing the air concentration of biuret obtained while sampling with an impinger filled with either MOP or tryptamine. (3) An improved derivatizing reagent, l-(methylanthracenyl) piperazine (MAP), which has a fluorescence sensitivity thirty times greater than tryptamine was evaluated in field studies. The analytical results indicate that there is no significant difference (p< 0.05, n= 6) in the concentration of polyisocyanate as determined by two impingers containing MAP and a third containing MOP when positioned in a side-by-side-by-side arrangement. (4) A new analytical method, capillary zone electrophoresis (CZE), was compared with high performance liquid chromatography (HPLC). CZE offers better selectivity and sensitivity for the analysis of HDI monomer when compared with HPLC.
Southwest Texas State University, Department of Chemistry, San Marcos, Texas