Development of tribenzamide functionalized electrochemical sensor for femtomolar level sensing of multiple inorganic water pollutants

Abstract

A novel tribenzamides derivative N-{4-[2-(1,3-Benzoxazolyl)]phenyl}-3,5-N,N′-bis(4-hexyloxybenzoyl)benzamide (BOC6), containing three amide groups, was successfully synthesized and characterized through multiple spectroscopy techniques. The ultrasensitive electrochemical platform was developed by fabrication of glassy carbon electrode (GCE) with synthesized multifunctional tribenzamide appended BOC6 for the removal of water pollutants. The performance of the engineered sensor was studied by its electrochemical characterization with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave anodic stripping voltammetry (SWASV). The modifier played a facilitating role between the GCE surface and the target metal ions by bringing analytes closer to transducer surface resulting in appearance of intense electrochemical signals. Under pre-defined optimized conditions of SWASV, the BOC6 modified electrode was able to attain distinct oxidative current signals of thallium, arsenic, and mercuric ions simultaneously in one voltammogram scan. The sharp electrochemical signal and peak potential shift of thallium (Tl), arsenic (As) and mercury (Hg) oxidation at −0.79 V, −0.06 V and 0.22 V respectively, versus reference electrode Ag/AgCl evidence the electrocatalytic role of BOC6/GCE as compared to bare GCE at −0.68 V, −0.01 V and 0.3 V, respectively. Moreover, it was found to sense femtomolar concentration of aforementioned toxic ions, much lower than the world health organization (WHO) and environmental protection agency (EPA) guidelines for drinking water [1]. The limit of detections (LODs) obtained on for Tl(I), As(III), and Hg(II) detection were 2.19 fM, 1.97 fM, and 2.52 fM, respectively. Conclusively, the designed electrode was portable, cost effective, resistant to the interference species, highly stable and gives repeatable and reproducible voltammograms of analytes via strong interactions with target ions even in real water samples.