A fast and selective electrochemical detection of vanillin in food samples on the surface of poly(glutamic acid) functionalized multiwalled carbon nanotubes and graphite composite paste sensor

Abstract

The electrochemical oxidation of vanillin (VL) in 0.2 M phosphate buffer (PB) solution of pH 6.5 was determined in food samples using an electrochemically polymerized glutamic acid (GA) functionalized multiwalled carbon nanotubes (MWCNTs) and graphite (GT) composite paste sensor (CPS). The surface concert and morphology of the sensing materials were examined using field emission scanning electron microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) measurements. The electrochemical oxidation kinetics of VL was discussed using parameters like solution pH, potential scan rate, temperature, and accumulation time. The selective electrochemical oxidation of VL was analyzed in the presence of metal ions, organic dyes, and sugars on the surface of the functionalized composite sensor. The modified sensor provided a fine linear dynamic range (0.50–18.0 µM) for the electrochemical oxidation of VL with a low limit of detection (LOD) of 0.0199 µM. The DPV measurement was performed for the analysis of VL in food samples on the surface of the functionalized composite sensor via standard addition method with adequate recoveries. Further, the equipped sensor needs lesser preparation cost and presents good reliability, repeatability, and reproducibility towards the electrochemical oxidation of VL. • Poly(glutamic acid) functionalized multi-walled carbon nanotubes and graphite composite sensor was developed. • Developed sensor materials were characterised using FE-SEM, EIS, and CV measurements. • Functionalised nano-composite sensor was more sensitive and selective for vanillin detection. • Equipped composite sensor gives a fine linear dynamic range for the oxidation of vanillin with a low limit of detection. • The modified sensor yields adequate recoveries for vanillin in different food samples.