Simultaneous electrochemical detection of hydroquinone and catechol in binary mixtures using poly(cysteine)-modified glassy carbon electrode

A simple and highly selective electrochemical method for simultaneous detection ofhydroquinone and catechol using a glassy carbon electrode modified with poly(cysteine) has been developed. The modified electrode has shown an excellent electrocatalytical effect on cyclic voltammetric oxidation ofhydroquinone and catechol in 0.1 mol L -1 acetate buffer solution (pH 5.0). In differential pulse voltammograms (DPV), oxidation peak potentials of hydroquinone and catechol recorded at poly(cysteine)-modified electrode in the same solution were separated by about 100 mV. At a bare electrode they overlapped giving a single broad peak due to the fouling effect by the oxidation product ofhydroquinone and catechol signal the fouling effect has been achieved by using poly(cysteine)-modified electrodes. Detection limit of hydroquinone in the presence of 1.0 ×10 -4 mol L -1 catechol was 8.0 × 10 -7 mol L -1 , and detection limit of catechol in the presence of 1.0 ×10 -4 mol L -1 hydroquinone was 1.0 × 10 -6 mol L -1 . The proposed method has been applied to simultaneous detection of hydroquinone and catechol in a water sample with simplicity and high selectivity.