Development of chemically modified carbon paste electrodes with transition metal complexes anchored on silica gel

The chemically modified silica gel with 3-(2-aminoethyl)aminopropyl]trimethoxysilane groups and p-aminobenzoic acid was used to immobilize the nickel (II) and cobalt(II) metallic ions complex initially. These materials were incorporated into a carbon paste electrode and its electrochemical properties were investigated. However, for dopamine and B6 vitamin solution, an enhancement of the anodic peak current was detected due to electrocatalytic oxidation. The electrodes presented the same response for at least 150 successive measurements, with a good repeatability. The modified electrodes are very stable and reproducible. The sensors were applied for dopamine and B6 vitamin determination in pharmaceutical preparation with success.