Polarographic study of 3-(4,5-dimethyl-2-thiazolylazo)-2,6-diaminopyridine in aqueous methanol medium

Abstract

The polarographic behaviour of the azo dye 3-(4,5-dimethyl-2-thiazolylazo)-2,6-diaminopyridine (DMTADAP) in methanol-water (65 + 35) at 20 °C was studied using various electrochemical techniques. In acidic media the reduction process involved two electrons, was diffusion controlled and showed a certain level of reversibility, whereas in neutral and alkaline media four electrons were consumed. In the latter instance a strong adsorption effect was apparent and the irreversibility of the process increased. The linear relationship between limiting diffusion current and DMTADAP concentration allowed the polarographic determination of DMTADAP over a wide concentration range, from 8.0 × 10^–7 to 6.8 × 10^–5M at pH 6.3, with a relative standard deviation of 1.2%(ten determinations at the 5.0 × 10^–6M level).