Porphyrin based nano-sized imprinted polymer as an efficient modifier for the design of a potentiometric copper carbon paste electrode

Abstract

In this study, a new carbon paste electrode (CPE) modified with porphyrin-based ion imprinted polymer (IIP) was designed and applied for the potentiometric determination of Cu²⁺ ions in aqueous solutions. The Cu-IIP was prepared using methacrylic acid, ethyleneglycoldimethacrylate monomers, in the presence of a copper complex of 5,10,15,20-tetrakis(4-hydroxyphenyl)-porphyrin. After polymerization, the prepared polymer was eluted by an aqueous solution of hydrochloric acid to leach the imprinted ions, which results in an obvious change in its color from purple to light brown. By microscopic analysis, the mean particle size of the prepared leached IIP was estimated to be around 60 nm. After characterization, the prepared IIP NPs were used as a modifier to design a modified CPE for potentiometric determination of Cu²⁺ ions in aqueous solutions. As found, at the optimum paste composition, the modified potentiometric sensor exhibited an excellent Nernstian response (30.15 ± 0.2 mV dec⁻¹) to the logarithm of Cu²⁺ ion concentration over the concentration range of 4.0 × 10⁻⁹ to 2.0 × 10⁻¹ mol L⁻¹. Moreover, the designed sensor showed a low detection limit (2.0 × 10⁻⁹ mol L⁻¹) with a short response time (∼5 s) and acceptable stability (at least 2 months). In addition, the sensor was successfully applied as a reasonable indicator electrode in potentiometric titration (against EDTA) with high precision and accuracy. Applicability of the IIP NP modified CPE was examined and confirmed by analysis of various water samples for the determination of Cu²⁺ ions.