Surface modified electrodes as a novel technique or characterizing adansonia digitata fruit

Abstract

The results presented in this thesis show that electrochemical analysis have been successfully carried out on raw plant material of Adansonia digitata fruit. All the four components of the A. digitata fruit, i.e. the greenish hairy outer covering, the woody covering, the inner white pulp and the seed have redox active moieties and gave clearly defined cyclic voltammetric responses when studied using bare carbon working electrode. They all displayed oxidation/reduction peaks at various potentials. The results show that both hydrochloric and sulphuric acid electrolyte media are suitable for the analysis of A. digitata fruit components. High electrodeposition rates and redox efficiencies revealed the significant role of the proton to the redox process. This was also confirmed by the poor response obtained in the non-aqueous media containing Scan rate dependence studies showed that the processes were diffusion controlled on bare carbon working electrode but in the case of modified electrodes, there were cases of surface attached species. The processes in the white inner pulp and the seed were shown to be one proton, one electron, processes from the pH dependence studies. Modification of the working electrode with a conducting polymer, polyaniline, and clay montmorillonite gave cyclic voltammetric responses with very well defined peaks. The modified electrodes yielded enhanced peaks with potentials shifted negatively suggesting there was electrocatalysis. The largest shifts were observed in the inner pulp .. and the seed parts of the fruit. The response from the clay-modified electrodes on the other hand, for all the fruit components showed larger shifts as compared to those of polyaniline modified electrodes.