EVALUATION OF 9-METHYLAMINO-METHYLANTHRACENE AS A CHEMICAL LABEL FOR TOTAL REACTIVE ISOCYANATE GROUP - APPLICATION TO ISOCYANATE OLIGOMERS,POLYURETHANE PRECURSORS, AND PHOSGENE

9-Methylamino-methylanthracene (MAMA) is a secondary amine compound wh ich can be used for derivatization and quantitation of isocyanate comp ounds by HPLC with detection by fluorescence and ultra-violet light ab sorbance. The compound has potential as a chemical label for determina tion of airborne total reactive isocyanate group (TRIG) compounds aris ing from partially polymerized polyurethanes and thermal decomposition products of fully cured polyurethanes. Six isocyanate oligomers and p olyurethane precursors based on methylene-bis-(phenylisocyanate) (MDI) , 1,6-hexamethylene-diisocyanate (HDI), and 2,4- and 2,6-toluenediioso cyanate (TDI) were assayed for isocyanate content using MAMA reagent. After reaction of isocyanate with MAMA, the urea derivatives were anal yzed by reversed phase HPLC using three detection / quantitation modes : fluorescence with excitation at 245 nm and emission at 414 nm, UV ab sorbance at 245 nm and UV absorbance at 370 nm. The ratio of absorbanc e at 245 nm and at 370 nm identified multiple peaks originating from i socyanate-containing compounds in each sample. The total amount of TRI G in each sample was then quantitated by absorbance of these peaks at both of the UV wavelengths. For the test samples, observed recoveries of TRIG by MAMA-HPLC assay ranged from 96 to 105%, in comparison to a reference titration assay. The technique was also evaluated for chemic al interference from phosgene gas. A single compound was found after r eaction of MAMA with phosgene which responded as two equivalents of TR IG.