Determination of residual aromatic amine hydrochlorides in process samples of di-isocyanate used in the manufacture of polyurethane A comparison of electroanalytical methods.

ABSTRACT

Aromatic diamine hydrochlorides have been determined in the presence of different amounts of hydrochloric acid by acid-base titration followed potentiometrically, by linear sweep voltammetry, by differential pulse voltammetry and also by direct DPV measurement. Tests on simulated and production samples have shown that the best results are obtained by using DPV at a mercury electrode, because of its good resolution, which makes it possible to achieve good accuracy (error < - 1 %) and good precision (rsd 1.5%) at 0.1M levels. Moreover, it has the advantage that neither preliminary treatment of the sample nor a trial titration is required.