Catalytic Adsorptive Stripping Voltammetric Procedure for Determination of Total Chromium in Environmental Materials

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Abstract
A sensitive catalytic adsorptive stripping voltammetric procedure for determination of traces of total chromium in environmental samples is reported. The method is based on the preconcentration of a Cr(III)H2DTPA complex by adsorption at the HMDE from an acetate buffer solution at the potential −1.0 V vs. Ag/AgCl. Total chromium was determined as Cr(III) after reduction of Cr(VI) to Cr(III) by NaHSO3. In order to stabilize the signal of Cr(III) the measurements were performed at 5 °C. The calibration graph for chromium for an accumulation time of 60 s was linear in the range from 5×10−10 to 5×10−8 mol L−1. The relative standard deviation for a chromium concentration of 1×10−8 mol L−1 was 3.9% (n=5). The detection limit for accumulation time of 60 s was about 8×10−11 mol L−1. The validation of the procedure was performed by the analysis of the certified reference materials.