Electrochemical Studies and Square Wave Voltammetric Determination of S‐[(2‐Guanidino‐thiazol‐4‐yl)methyl]isothiourea hydrochloride and 2‐Guanidino‐1,3‐thiazole

Abstract

S-[(2-Guanidino-thiazol-4-yl)methyl]isothiourea hydrochloride (GTAMITU) and 2-guanidino-1,3-thiazole (GTA) were studied at hanging mercury drop electrode under conditions of square-wave voltammetry and in the function of the electrode potential for different adsorbate concentrations. The experimental data of adsorption were obtained from the measurement of differential capacity of the double layer, the measurement of zero charge potential and surface tension at the zero charge potential. The received results point to the adsorption of molecules directly with the guanidine group to the mercury surface and suggest that the molecules are not placed flatly on the mercury surface. This kind of arrangement of molecules enables electron transfer, which is the basis of their electroactivity and causes the compounds to act as electrocatalysts. New adsorptive catalytic methods for voltammetric (SW AdSV) determination of GTAMITU and GTA were developed. The dependence of the peak current on pH, buffer concentration, and nature of the buffer were studied. The best results according to the shape and sensitivity of the peak were recorded in citrate buffer at pH 2.0 for GTAMITU and in phosphate-citrate buffer at pH 2.96 for GTA. This electroanalytical procedure enabled to determine GTAMITU and GTA in the concentration range 5 10 À8 -4 10 À7 mol L À1 and 8 10 À7-8 10 À6 mol L À1 respectively. Precision, repeatability and accuracy of the method were checked. The detection and quantification limits were found to be 1.3 10 À8 and 4.4 10 À8 mol L À1 for GTAMITU and 2.6 10 À7 and 8.0 10 À7 mol L À1 for GTA respectively.