A New Approach for the Voltammetric Determination of Amoxicillin in the Dosage Form Using Azo Coupling Reaction with Sulphanilamide

The novel method of amoxicillin (AM) determination has been developed using single-sweep polarography. The proposed method is based on the obtaining of yellow coloured azo compound due to azo coupling reaction of previous diazotized sulphanilamide (SA) (in the medium of 0.6 M hydrochloric acid) with amoxicillin at pH=9.0 with the further reduction of the formed analytical form on a dropping mercury electrode. Voltammetric determination of amoxicillin is carried out due to the reduction peak of azo group of the obtained azo compound in the presence of 0.05 mol ? L^?1 Na₂B₄O₇ as a background electrolyte at the potential E_c^p2=?0.55 V and potential sweep rate of 2.5 V ? s^?1. The developed voltammetric method has two linear ranges of the determined concentrations (0.05–2.0) ? 10^?5 mol ? L^?1 and (0.2–1.0) ? 10^?4 mol ? L^?1 and the high sensitivity: LOD without the removing of unreacted sodium nitrite is 1.1 ? 10^?6 mol ? L^?1, and 7.2 ? 10^?7 mol ? L^?1, when NaNO₂ excess is removed using urea. The developed voltammetric technique of AM determination has been approved during the analyses of tablets and oral suspension.