Speciation of antimony in anti-leishmanial drug using two different chemical receptors and adsorptive anodic stripping voltammetry on glassy carbon electrode

Abstract

This paper describes an application and comparison of two stripping voltammetric methods for the speciation of antimony. These methods are based on the formation of the antimony complexes in the presence of two separate chemical receptors, rivastigmine and hematoxylin, and their accumulation on a glassy carbon electrode. They were utilized for the first time to determine Sb(III) and Sb(V) in meglumine antimonite used in the treatment of leishmaniasis. For this purpose, first, the peak current of Sb(III) for a certain amount of drug sample was separately measured using two different receptors. Then, for the same amount of sample, the peak current of total antimony was separately determined in the presence of each receptor by standard addition method after the reduction of Sb(V) ions to Sb(III) with ʟ-cysteine. The current value of Sb(V) was calculated by subtracting the peak current of Sb(III) from that of total antimony for each addition. Then, the calibration curves for the current values of Sb(V) and total antimony were plotted, and the concentrations of Sb(V) and total antimony were determined. The Sb(III) concentration was calculated from the difference between these two values. The Sb(III) and Sb(V) contents were found 16.99 and 82.93 mg cm−3 in the presence of rivastigmine, and 16.59 and 77.96 mg cm−3 in the presence of hematoxylin, respectively. These results showed that both methods were successfully applied to determine Sb(III) and Sb(V) in meglumine antimonite.