Electrochemical behavior and polarographic determination of auronofin

Auronofin in a 50% ethanol:water solution yields, on the dropping mercury electrode, a reduction wave whose E1/2 is a function of pH in the 2 less than pH less than 9 range (E1/2 = -0.036-0.054 pH), and acquires a constant value above pH 9 (E1/2 = -0.50 V, versus saturated calomel electrode). The influence of the variables which affect the reduction process of auronofin in tripotassium phosphate medium was studied. The electrochemical process is reversible and diffusion controlled. Coulometry showed that one electron is involved in the reduction of the drug. Analytical methods are proposed for the determination of auronofin at micromolar levels by DC and DP polarography, with relative standard deviations of 3.2 and 2.4%, respectively.

Voltammetric determination of vitamin D3 with a rotating glassy carbon electrode

A voltamperometric study (DC and DP) on the electroanalytical behaviour of vitamin D(3) in a methanolic solution using LiClO(4) as the supporting electrolyte and working with a glassy carbon electrode was carried out. Vitamin D(3) exhibits an oxidation wave (DC) or peak (DP) at potentials close to +1.1 V (versus SCE). The optimum experimental conditions for the best reproducibility of the voltamperometric signal were determined and the different parameters affecting the electrochemical process were studied. The electrochemical process was seen to be irreversible and, under certain conditions, adsorption of vitamin D(3) onto the electrode surface was observed. A voltamperometric procedure for the determination of vitamin D(3) in a concentration range of 2 x 10(-6) - 2 x 10(-4) M is proposed. The detection limit is of the order of 2 x 10(-6) M and the relative standard deviations are 1.1% (DC) and 2.6% (DP), respectively.