Desenvolvimento de método por voltametria de redissolução anódica empregando a eletrodissolução para a determinação de cádmio e chumbo em amostras de eletrodo revestido modelo E6013

Abstract

The determination of cadmium (Cd+2) and lead (Pb+2) present in E6013 electrode samples was performed using anodic redissolution square wave voltammetry (VOQRA) and a bismuth film electrode (BiFE). As a comparison, mass spectrometry with inductively coupled plasma (ICP-MS) was used. Electrodissolution was used in comparison with acid digestion in the heating plate in the sample preparation step for the determinations of Cd+2 and Pb+2 in the metal parts of the E6013 electrode samples. For electrodissolution, the use of syringes as low-cost electrolytic vats has been proposed, using as an electrolyte a combination of solutions of nitric acid (HNO3) 1.0 mol L-1 and hydrochloric acid (HC) 0.1 mol L-1 . A charge study showed that 900 Coulombs were sufficient to obtain a good electrodissolved mass in a short period of time. The stage of preparing samples by electrodissolution showed recovery rates in the range of 92.1 to 103.6% for the analytes, showing better in relation to the acid digestion in the heating plate. The optimization of VOQRA conditions resulted in a gain of sensitivity in relation to the proposed initial conditions, obtaining in this technique instrumental detection limits (LD) equal to 0.65 µg L1 for Cd+2 and 1.28 µg L-1 for Pb+2 . The method was applied to four samples of coated electrode model E6013, and in all cases the Cd+2 concentration was below the LD and the Pb+2 concentrations obtained by VOQRA were in agreement with 95% confidence with those obtained by ICP -MS.