Selective membrane electrode potentiometry and spectrophotometry of a photochemical reaction of thioredazine hydrochloride.

A PVC membrane electrode of the coated wire type was prepared which is selective for thioredazine. It showed a Nernstian response over a thioredazine concentration range 6.3 x 10(-6) to 2.5 x 10(-3) M, at 25 degrees C, and was selective, precise, and usable within the pH range 2.1-7.0. The standard electrode potentials, E degrees, were determined at different temperatures and used to calculate the isothermal temperature coefficient of the electrode. The photoreaction occurring in thioredazine solution exposed to daylight did not affect the electrode performance. This reaction was investigated kinetically to determine its rate constant and half-life at different temperatures.