Determination of trace levels of Cd(II) in tap water samples by anodic stripping voltammetry with an electrografted boron-doped diamond electrode

A boron-doped diamond electrode modified by 0.5 mM 4-aminomethyl benzoic acid was used for electrochemical determination of Cd2+ in tap water samples by anodic stripping voltammetry. This method is based on the electrochemical reduction of 4-aminomethyl benzoic acid on the electrode followed by the determination of Cd2+ with a single well-defined reduction peak at 0.72 V versus Ag/AgC1 in acetate buffer solutions at pH 6.0. Optimal conditions were established with respect to electrode pretreatment, time accumulation, potential accumulation, scan rate, and pH. Accurate (r(2) = 0.9989, n = 6) calibration curves were obtained for Cd2+ concentrations ranging between 2 ppb and 50 ppb. Other dissolved metals (Ca, Mg, Zn, Mn, Fe, Cu, Al, Co, Pb, and Ni) have no interference on the Cd2+ calibration curves. The achieved detection limit was 0.2 ppb. High accuracy and reproducibility of the results as well as excellent stability of the electrode material proves superb capabilities of this Cd2+ detection system. Recovery in the range of 97-102% further confirmed the usefulness of the proposed method to analyse Cd2+ in tap water samples. The results with SRM1640 were in good agreement with those by inductively coupled plasma optical emission spectrometry.