Electrochemical behavior and analytical determination of Reactive Red 231 on glassy carbon electrode

Abstract The electrochemical behavior of the Reactive Red 231 has been investigated in phosphate buffer solutions by cyclic and differential pulse voltammetry on a glassy carbon electrode. The electrochemical oxidation of the dye exhibits two well-defined pH-dependent anodic peaks. The first one is quasi-reversible, while the second one at higher potential is irreversible process and mainly diffusion-controlled. The anodic oxidation properties of the dye in phosphate buffer at pH 3.77 allowed its sensitive determination at sub-micromolar levels by anodic differential-pulse voltammetry and presented a linear relationship from 0.25 μM to 200 μM. The reproducibility (at the 50 μM level) expressed in terms of relative standard deviation was 4.7% (for five determinations). A detection limit of 0.20 μM was achieved. The detection limit was around 50 times lower than that verified by spectrophotometric method. The applicability of the method was demonstrated by the determination of the dye in environmental water samples.