Determination of Cadmium by Adsorptive Stripping Voltammetry of a Cadmium-Calcein Blue Complex

A sensitive stripping voltammetry for the determination of cadmium, with an adsorptive accumulation of complexes on a hanging mercury drop electrode with Calcein Blue, 8-[N, N bis(carboxymethyl)aminomethyl]-4-methylumbelliferone, has been developed. After accumulation of the complex, the electrode potential is scanned with differential pulse modulation and the reduction current for cadmium is observed at -0.8V. Under optimum conditions (1μM Calcein Blue, pH 7.2, adsorption at -0.2V for 3min), the detection limit was 0.015nM. Interference from iron can be reduced by the addition of citrate ion. The method was applied to the determination of cadmium in fresh water samples.