The gold nanoparticle sensitized pRGO-MWCNTs grid modified carbon fiber microelectrode as an efficient sensor system for simultaneous detection of three dihydroxybenzoic acid isomers

Abstract

A sensitive and novel carbon fiber microelectrode (CFME) modified by the gold nanoparticles sensitized partially reduced multilayer graphene oxide-multiwall carbon nanotubes (pRGO-MWCNTs/Aus) was developed for the simultaneous determination of dihydroxybenzoic acid (DHBA) isomers. The surfaces of modified microelectrodes were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS). The synergistic effect of pRGO-MWCNTs and Aus reduced the overpotential, enhanced the electrocatalytic ability and improved the peak shape of DHBAs. The modified microelectrode exhibited a good electrochemical behavior followed by well-separated oxidation peaks of 2,3-DHBA, 2,5-DHBA and 2,6-DHBA at 0.637 V, 0.565 V and 0.950 V, respectively, so that the three DHBA isomers can be detected simultaneously without previous separation. And the peak currents were linearly dependent on 2,3-DHBA, 2,5-DHBA and 2,6-DHBA concentrations using differential pulse voltammetry (DPV) method in the ranges of 8–9000 nM, 8–8000 nM and 20–8000 nM with detection limits of 0.34 nM, 0.55 nM and 1.3 nM (S/N = 3) for the simultaneous determination, respectively. The microsensor has good repeatability, stability, reproducibility and acceptable anti-interference performance. And it has been successfully applied to the real-time monitor the uptake of three DHBA isomers by plant roots.