Voltammetric sensors based on schiff bases for cation anion recognition

Abstract

Potent electrochemical sensors developed using Schiff base as an additive for the fabrication of screen-printed electrodes (SPE) were explored. A series of Schiff base derivatives having methylene bridge forming a wedge between two Schiff base motifs have been selected as modifier for the fabrication of modified SPEs. Structural variation of Schiff bases depends upon the presence of secondary substituent around each imine bond. Substituent can be either electron withdrawing or electron donating group which ultimately affects the recduction potential of imine double bond. Further, coordination ability of the ionophore was also influenced. The electrochemical and ion-recognition behavior of ionophore molecules namely, SMS-0, SMS-1, SMS-2, SMS-3, SMS-4, SMS-5a and SMS- 5b (used for modification) have been discussed in detail using differential pulse voltammetric (DPV) and cyclic voltammetric (CV) studies. For the modification of working electrodes of the SPEs, ionophores were used as additives and mixed with carbon ink before fabrication. With the inclusion of the ligand in the ink, performance of the SPE enhanced. Scanning electron microscopy (SEM), CV data and Energy-dispersive X-ray spectroscopy (EDX) and was analysed in order to confirm the modification. Differential pulse voltammograms of SMS-0 modified SPEs in the presence of Al (III) showed a characteristic cathodic current at and#8722;0.054 V. This characterstic peak was used for quantitative application of ionophore. A linear response of the sensor was found in concentration range of 0.67 4.59 and#956;g Land#8722;1 of the analyte. The detection limit was found to be 2.26 ng Land#8722;1 for Al (III). The proposed chemosensor selectively detects Al (III) in the presence of some alkali, alkaline earth, transition metal ions like Zn (II), Cd (II), Hg (II) and Pb (II). Complexation behavior of the ionophore for the metal ion has also been supported by theoretical studies.