Electrochemical detection of NADH and dopamine in flow analysis based on tetraruthenated porphyrin modified electrodes

Modified electrodes with molecular films of a tetraruthenated cobalt-porphyrin complex have been employed in the amperometric detection of NADH and dopamine. The electrochemical oxidation of these bioanalytes can be monitored at the onset of the RuIIIII redox wave (E ° = 0.70 V vs AgAgCl), exhibiting a very sharp peak consistent with a rapid and efficient electron transfer process. Because of the rectifying properties of the molecular films, a high selectivity for reduced species has been observed in scanning measurements. Very good signal to noise ratios have been obtained in flow analysis, ensuring a detection limit in the ppb range, for NADH and dopamine.