Sensitively-selective determination of Propyl Paraben preservative based on synergistic effects of polyaniline-zinc-oxide nano-composite incorporated into graphite paste electrode

The application of Propyl Paraben (PP) as a chemical preservative has expanded and diversified. Widespread use of products containing PP has resulted in its ubiquitous occurrence in environment and biological fluids among the general population. Several in-vivo studies have associated PP with estrogenic activity and malfunctioning of reproductive organs. In this work, we have developed a highly sensitive voltammetric sensor for PP detection based on polyaniline-zinc-oxide nano-composite modified carbon paste electrode (PANI/ZnO/MCPE). The synthesized nano-composite was characterized using spectroscopic techniques. Experimental conditions such as supporting electrolyte, their pH and scan rate were optimized to attain a well defined PP anodic peak current at 690 mV. Our experiments indicate a strong synergistic interaction between ZnO and PANI, resulting in the magnification of PP current with a declined over-potential, compared to bare CPE. We have proposed a mechanism of π-π interaction between PP and PANI/ZnO/MCPE. The electrode process was characterized to be irreversible; diffusion controlled and proceeds with an exchange of 1e- and H⁺. Noteworthy analytical performance over wide linear range from 100.0 to 1.0 μM, with a detection limit of 0.13 μM and anti-interference characteristics were ascertained. A significant advantage of this sensor is its inability to detect micro molar concentrations of ascorbic acid (AA) while PP is detected at micro levels in the presence of high concentrations of AA. The versatility of this sensor was demonstrated by efficaciously applying it to trace analysis of complex real samples such as pharmaceutical formulations, biological samples and lake water with good recoveries.