Voltammetric behavior of tiopronin on carbon paste electrode modified with nanocrystalline Fe₅₀Ni₅₀ alloys.

A simple and sensitive sensor was proposed for the rapid determination of tiopronin (TP) using a carbon paste electrode (CPE) modified with synthesized nanocrystalline Ni50-Fe50 alloys (nano-Ni50-Fe50) and ferrocene carboxylic acid (FcCa). The synthesized nano-Ni50-Fe50 was characterized by different methods such as TEM, SEM and XRD. The electrochemical oxidation of TP on the nano-Ni50-Fe50/FcCa carbon paste electrode (nano-Ni50-Fe50/FcCa/CPE) was studied. The nano-Ni50-Fe50/FcCa/CPE exhibited good electrocatalytic properties towards oxidation of TP in phosphate buffer solution (pH7.0) with an overpotential of about 500 mV lower than that of the bare electrode. The rate constant for the catalytic oxidation of TP was evaluated by rotating disk voltammetry and the value of kc was found to be 3.2 × 10(7) cm(3)mol(-1)s(-1). Using differential pulse voltammetry (DPV), the determination of TP was explored at the modified electrode. The results indicated that the differential pulse response of TP was linear with its concentration in the range of 0.01-50.0 μM. The detection limit was 7.46 nM (S/N=3). The proposed sensor was successfully applied for the determination of TP in tablet and urine samples.