Electro-organic polymerization of aniline derivative on carbon-based electrode and its pH sensing in food samples

Poly(1-naphthylamine) (pNPA), similar to polyaniline, is a significant conducting polymer frequently synthesized through electrochemical methods in acidic or non-aqueous environments. Unlike conventional preparation, this work demonstrates the fabrication of pNPA via a neutral pH-assisted open-circuit potential technique on a multiwalled carbon nanotube modified glassy carbon electrode (GCE/CNT@pNPA). Electrochemical cycling of 1-naphthylamine (1-NPA) adsorbed GCE/CNT in pH 7 phosphate buffer solution (PBS) led to the formation of a redox active polymeric structure. Physicochemical characterization of CNT@pNPA by microscopic (SEM) and spectroscopic (Raman and FTIR) methods confirmed the electro-organic synthesis of pNPA on CNT. Notably, GCE/CNT@pNPA showed good Nernstian behavior with negligible electrocatalytic activity to various electroactive biochemicals. The stability of peak current and potential further highlighted the selective electrochemical pH sensing capability of GCE/CNT@pNPA. Under optimal differential pulse voltammetry conditions, the GCE/CNT@pNPA was extended for analysis of pH values in various food samples. In near future, GCE/CNT@pNPA can be further miniaturized and could be extended for online monitoring of pH in various samples.