Tuning Selectivity and Sensitivity of Mixed-polymeric Tetraruthenated Metalloporphyrins Modified Electrodes as Voltammetric Sensors of Chloramphenicol

Mixed Ni-Co tetraruthenated porphyrin films were successfully electropolymerized on glassy carbon electrodes in alkaline solutions (pH=13) of NiTRP and CoTRP, giving excellent electrocatalytic responses for determination of the antibiotic drug chloramphenicol. Electrodes with four different compositions were obtained by varying the ratio of NiTRP and CoTRP in the deposition solution. For the characterization of these materials, SEM, ICP-MS, EIS and CV were explored. The porphyrin modified glassy carbon electrodes presented two oxidation peaks for chloramphenicol (except for Ni-25). The potential shifted to lower values as the percentage of CoTRP increased decreasing its oxidation potential in more than 200 mV for Ni-50 as compared to Ni-100. Interestingly, the materials with cobalt content larger than 50 % did not show the typical catalytic response of the (NiOOH)-O-III species, but rather showed an increase in current at potentials larger than 0.4 V, demonstrating the key role played by nickel in this type of materials. The composition of polymeric mixed porphyrin materials influenced the oxidation current response of both redox waves, resulting in different sensitivities on the calibration curves.