Evaluation of the NIOSH draft method 5525 for determination of the total reactive isocyanate group (TRIG) for aliphatic isocyanates in autobody repair shops

{This paper evaluates the performance of the NIOSH draft method 5525 for analysis of monomeric and TRIG aliphatic isocyanates in autobody repair shops. It was found that an optimized pH gradient enhanced noticeably the resolution and, therefore, identification of aliphatic isocyanates. Samples proved to be very stable for at least a year when stored at -13 degreesC in the freezer, and no major stability problems were found for the MAP reagent. The detector response factor RSD for selected MAP ureas was 40%2in the fluorescence (FLD), 3%2in the UV at 254 nm (UV254), and 1%2in the UV at 370 nm (UV370). The mean FLD/UV254 and UV254/UV370 detector response ratios of standards were 31.7 (RSD = 37.8) and 17.1 (RSD = 5.4), respectively. The FLD/UV254 ratio in bulks varied from 0.41 to 1.97 times the HDI monomer ratio. The mean UV254/UV370 ratio in bulks was 16.1 (range 14.1 to 19.2