DEVELOPMENT OF A NOVEL DERIVATIZATION REAGENT FOR THE SAMPLING AND ANALYSIS OF TOTAL ISOCYANATE GROUP IN AIR AND COMPARISON OF ITS PERFORMANCE WITH THAT OF SEVERAL ESTABLISHED REAGENT

Analytical reference standards generally are not available for non-mon omeric isocyanate species, making accurate identification and quantita tion by high-performance liquid chromatography (HPLC) difficult. A suc cessful derivatizing reagent must react rapidly with all isocyanate gr oups, the derivatized isocyanate must be detectable selectively and at very low levels, and the detector used for quantitation must give a r esponse proportional to the number of derivatized isocyanate groups pr esent. A novel derivatizing reagent, 1-(9-anthracenylmethyl)piperazine (MAP),was prepared in an attempt to achieve these goals. Derivatives were prepared by reacting five mono- and difunctional isocyanates with MAP and three other established isocyanate derivatizing reagents. The se reagents included 1-(2-methoxyphenyl)piperazine (MOPP), 9-(methylam inomethyl)anthracene (MAMA), and tryptamine (TRYP). The relative react ivities of MAP, MOPP, TRYP, and MAMA with phenyl isocyanate were found to be 100, 88, 30, and 25, respectively. Average molar absorptivities at the absorbance maxima +/- compound-to-compound variabilities were, for MAP: 1.47 x 10(5) +/- 3.50%; MAMA: 1.38 x 10(5) +/- 7.07%; and TR YP: 3.98 x 10(4) +/- 13.1%. Average fluorescence responses were, for M AP: 100 +/- 32.6%; MAMA: 41.0 +/- 58.8%; and TRYP: 2.27 +/- 15.6%. A c omparison of MAP and MOPP ureas by HPLC/ultraviolet (UV)/electrochemic al (EC) gave average responses for UV, EC, and EC/UV for MAP: 117 +/- 7.3%, 52.1 +/- 6.6%, and 0.447 +/- 10.7%, respectively; for MOPP: 24.3 +/- 62.5%, 76.7 +/- 28.5%, and 4.28 +/- 59.1%, respectively. The favo rable performance of MAP warrants its further study as a reagent for t he determination of total isocyanate group in air.