Determination of Methyl Violet 2B Using Polarographic and Voltammetric Methods at Mercury Electrodes
Abstract
Direct current tast polarography and differential pulse polarography at a dropping mercury electrode and direct current voltammetry, differential pulse voltammetry, and differential pulse adsorptive stripping voltammetry at a hanging mercury drop electrode were used for the study of the electrochemical behavior of methyl violet 2B and for its determination in buffered aqueous media and model water samples. The optimum medium for all the techniques used was 0.04 mol L-1 Britton Robinson buffer of pH 4.0.
The attained limits of quantification of methyl violet 2B were as follows: 1.7 μmol L-1 (direct current tast polarography at the dropping mercury electrode), 0.16 μmol L-1 (differential pulse polarography at the dropping mercury electrode), 65 nmol L-1 (direct current voltammetry at the hanging mercury drop electrode), and 45 nmol L-1 (differential pulse voltammetry at the hanging mercury drop electrode). The lowest limit of quantification of 13 nmol L-1 was obtained using differential pulse adsorptive stripping voltammetry at the hanging mercury drop electrode (with the accumulation potential of -500 mV and the accumulation time of 600 s), which was further applied to model samples of drinking (limit of quantification of 40 nmol L-1) and river (limit of quantification of 20 nmol L-1) water.