Cobalt oxide/tetraruthenated cobalt-porphyrin composite for hydrogen peroxide amperometric sensors

A new composite material constituted by mu-{5,10,15,20-tetra(4-pyridyl)porphyrinato cobalt(iii)}-tetrakis-{chloro-bis-(2,2'-bipyridine)ruthenium(ii)} complex (or CoTRP) and cobalt oxide, exhibiting high stability and sensitivity for the quantification of hydrogen peroxide, was obtained by the electrochemical polymerization of the tetraruthenated cobalt porphyrin in alkaline medium. The optimized experimental conditions for the preparation of the modified glassy carbon electrodes and for analysis of H2O2 were carefully determined. Fast sequential analysis (120 determinations h(-1)) in a wide linear dynamic range (5.0 x 10(-7) mol L(-1) to 2.0 x 10(-3) mol L(-1)), with high sensitivity and low detection limit (2.0 x 10(-7) mol L(-1)), was achieved by using these electrodes and the batch injection analysis (BIA) technique. Such characteristics allied to a good stability were explored for the specific determination of hydrogen peroxide in six commercial cosmetics and pharmaceutical product samples, giving results in excellent agreement with those obtained by the spectrophotometric method.