Influence of cobalt content on nanostructured alpha-phase-nickel hydroxide modified electrodes for electrocatalytic oxidation of isoniazid

Fluorine doped tin oxide electrodes modified with nanostructured alpha nickel hydroxide, cobalt oxi-hydroxide and mixed alpha nickel/cobalt hydroxide electrodes were evaluated for determining isoniazid concentration by cyclic voltammetry (CV) and batch injection analyses (BIA) associated with amperometric detection. The different cobalt contents showed distinct features regarding isoniazid oxidation potential and current magnitude. The modified electrodes containing 25% cobalt presented about 3- and 7.5-fold greater sensitivity as amperometric isoniazid sensors than pure Ni(OH)2 electrodes, respectively for CV and BIA assays. This characteristic associated with high stability and reproducibility ensured BIA detection limits as low as 1.37 × 10−7, 5.19 × 10−8 and 4.94 × 10−8 mol L−1 for Ni-100, Ni-75 and Ni-50 electrodes respectively, as well as a high analyses throughput (about 400 h−1). The resulting electrodes are promising for other applications, once presents elevated sensitivity and the additional advantage of allow the researcher choose the best working potential, just varying the constitution of the modifier film.