Electrochemical ion imprinted polymeric film in sensor development for Cd(II) ions determination in water

Imprinted polymers define robust and artificial materials able to mimic recognition processes of such analytes, such as proteins, small molecules, or ions. The process results in the selective formation of ion-sized imprinted cavities, which are complementary to a specific template in terms of its functional groups. These materials can be easily applied to identify, monitor and remove the target ions in water environment. In this view, the ion imprinted polymers (IIPs) can be described. Their synthesis can be carried out both chemically and electrochemically. The latter leads to the preparation of imprinted films, which are compatible in conjunction with transducers in sensor development. Very few works report the electrochemical synthesis of ion imprinted polymers and their application as sensors for metal ion detection. With this regard, we propose the synthesis, optimisation, characterisation and subsequent application of an electrosynthesised IIPs for the electrochemical detection of cadmium (II) in water. The proposed sensor was prepared by electropolymerisation of 4-aminophenylcarboxylic acid (4-APA) monomer in presence of Cd(II) ions, which acts as the template. The screen printed graphite electrodes (SPGE) were used as transducer during sensor development, whereas the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were selected as the electrochemical methods for the synthesis and Cd(II) ions sensing, respectively. The incubation of the developed sensor in EDTA 500 mM involved into remove the template and the formation of specific recognition cavities into the polymer. A multivariate optimisation was employed for studying the effect of four independent parameters on electrochemical performances of the sensor. The electrochemical characterisation of sensors was performed in ferrocyanide-ferricyanide redox couple and in KCl 0.1 M, the latter revealing redox properties from the polymeric film. The performances of sensors and the control (NIP) was observed in sodium acetate buffer (50 mM, pH = 5) over the Cd(II) concentration range 10 – 500 nM.