Electroanalytical study of a benzodiazepinooxazole: Mexazolam

Summary

The electroanalytical behaviour of 10-chloro-11b-(2-chlorophenyl)-2,3,7,11b-tetrahydrooxazolo[3,2-d][1,4]-benzodiazepin-6(5H)-one (Mexazolam) was studied in the pH-range 1–13. The compound suffers a hydrolysis process, which can be followed by voltammetric techniques. The reduction process of Mexazolam is irreversible in the whole pH range 1–13 studied; the cathodic reactions of its hydrolysis products are irreversible at pH values lower than 7 and reversible in neutral and alkaline media at a scan rate range of 0.1–40 V·s⁻¹. The electrode process attributed to the reduction of the carbonyl group is predominantly adsorption-controlled and the reduction of the iminium group of the different species of Mexazolam is diffusion-controlled. A differential pulse polarographic method has been developed upon the basis of the reduction of the protonated iminium form. The relationship between reduction peak current and concentration is linear up to at least 13 ppm. The reproducibility of the method in terms of relative standard deviation (RSD) was smaller than 1.6% for ten determinations, at a concentration level of 5.51×10⁻⁶ and 2.62×10⁻⁵ mol/l. A determination limit of 80 ppb was obtained.