Abstract
The Marcali method for the analysis of airborne toluenediisocyanate was evaluated for its response to the two isomers of the compound. The absorbance of the chromophore obtained from 2,6 TDI is approximately 47% less than that from the 2,4 isomer of TDI when measured at 550 nm. In addition, the absorbance spectra of the 2,6 isomer exhibits a shifting of the wavelength of maximum absorbance from 550 nm to 565 nm. A simple modification of the method involving changes in diazotization time and temperature is proposed to eliminate this isomer effect.