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(H) 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 1(-1) Cd(II) was observed with a sensitivity of 2.83 muA mol(-1) 1, limit of detection 1.0 x 10(-7) Mol 1(-1). Cd(H) spiked in a natural water sample was determined with 99% mean recovery at 10(-7) Mol 1(-1) level. Interference were also evaluated. (C) 2003 Elsevier Science B.V. All rights reserved.