Development of Electrochemical Sensors Based on Electrosynthesized Ion Imprinted Polymers for Cobalt (Co²⁺) Ions Determination in Water

Preliminary results on an electrosynthesized ion imprinted polymeric (IIP) film for Co²⁺ ions determination in sensor development are here reported. The sensor was prepared by electropolymerization of poly-2-aminophenol (2-AP) monomer in presence of Co²⁺ ions, which acts as the template. The screen-printed carbon electrodes (SPCE) were used as transducer during sensor development, whereas the cyclic voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) was used for the electrochemical characterization of sensor and for Co²⁺ ions sensing, respectively. The measurements consisted of 5.0 mmol FeCN-KCl solution prepared in PBS at pH 7.8 (0.1 M) for CV assay within a potential range between −0.2 and 1.2 V and EIS essays an open circuit and data was settled through a sinusoidal potential perturbation of 0.01 V amplitude and 57 as frequency values that were logarithmically distributed over a range of frequencies between 0.01 Hz and 100 kHz. A multivariate optimization based on design of experiment (DOE) was employed to study the effect of parameters on electrochemical performances of the sensor. After electropolymerization and rinsed electrodes was incubated in different Co²⁺ concentrations ions to be tested through EIS. A non-imprinted polymer (NIP) was prepared as a control under the same protocol, but without adding the template into the polymerization mixture. The results showed in the first experiment an adequate response for the characterization and testing of IIP and NIP. For these preliminary tests, the electropolymerization patterns of IIP polymers were found to be consistent with the ones previously reported. The first electropolymerization CV cycle of the IIP showed a unique peak at +0.3 V during polymerization process and the EIS essays during the IIP showed a consistent behavior for the lowest concentrations that were tested (1-8 μM).