Determination of phytochelatins by cathodic stripping voltammetry in the presence of copper(II)

The voltammetric behaviour of the copper-phytochelatin (PC) complex in 0.5 M NaCl at pH 8.1 at the hanging mercury drop electrode was investigated. An analytical method that utilizes the current produced, in the presence of Cu(II), by a copper complex with the cysteine groups of the adsorbed PCs, was developed. At a Cu(II) concentration of 2.5 X 10(-6) M, sensitive measurements can be achieved by using differential pulse cathodic stripping voltammetry. The effects of the experimental parameters such as preconcentration time, adsorption potential and copper concentration on the peak current are discussed. The stripping current was found to be proportional to the total concentration of thiol groups of phytochelatins (SHPC). The sensitivity was 8 X 10(-3) nA s(-1) nM(-1). Using an accumulation time of 300 s at -0.4 V, an SHPC concentration of 1 nM can be detected.