Cadmium (II) electrode based on plasticized PVC membranes with 1-furoyl-3,3-diethyl thiourea as ionophore and tributylphosphate as plasticizer has been developed. The membrane was applied on a support of conducting epoxy resin. Some parameters of evaluation of the electrode are presented in this work. The constructed electrode showed linear response in the concentration range of 10-6-10-3 mol/dm 3 , had a slope of 28.5 mV/decade, a detection limit (DL) of 2.10-6 mol/dm 3 and a lower limit of lineal range (LLLR) of 4.2.10-6 mol/dm 3. The static response time obtained was less than 20 seconds. The Cd/S relationship in the membrane was 1:1, as was determined by chemical microanalysis of energy dispersive X-ray spectroscopy (EDS). The constructed electrodes had a lifetime of 5 days.

A minimal instrumentation micropolarograph was built, and its metrological characterization was performed. The oxidation of K 4 [Fe(CN) 6 ] was studied by linear voltammetry. A microdisc and a bar of carbon were used as working and auxiliary electrodes, respectively. A bar divided into compartments of copper-internal solutioncotton was used as reference. The linear coefficient of determination between the limiting current and the concentration was 0.9926, in the range of 10-2-10-1 mol L-1. The coefficient of variation of ten voltammograms at 0.08 mol L-1 was 1.8 %, being inferior to the maximum value reported for these methods. Mood and Kruskal-Wallis tests did not show significant differences between voltammograms. In the range of linear correlation coefficients of potential sweep 0.9488 to 0.9989, no sweep influence on voltammograms was observed. The expanded uncertainty associated with the determination of the limiting current was 1.9 µA. The linear voltammograms for oxidation of ascorbic acid and KI were obtained, showing correspondence with the reported results.