Evaluation of a carbon paste electrode modified with organofunctionalized amorphous silica in the cadmium determination in a differential pulse anodic stripping voltammetric procedure.

The determination of cadmium using a carbon paste electrode modified with organofunctionalized amorphous silica with 2-benzothiazolethiol was investigated. The Cd(II) oxidation peak was observed around -0.80 V (vs. SCE) in phosphate buffer (pH 4.0) in differential pulse anodic stripping voltammetry. The best results were obtained under the following optimized conditions: 1 min accumulation time, 50 mV pulse amplitude, 20 mV s(-1) scan rate in phosphate buffer pH 4.0. Using such parameters a linear dynamic range from 5.6 x 10(-7) to 3.5 x 10(-5) mol l(-1) Cd(II) was observed with a sensitivity of 2.83 microA mol(-1) l, limit of detection 1.0 x 10(-7) mol l(-1). Cd(II) spiked in a natural water sample was determined with 99% mean recovery at 10(-7) mol l(-1) level. Interference were also evaluated.