An electrochemical sensor based on fullerene nanorods for the detection of paraben, an endocrine disruptor

Abstract

In the present work, fullerene nanorods (C₆₀NRs) were synthesized by liquid–liquid interface and characterized using Fourier transform infrared (FTIR) spectroscopy, field emission electron microscopy (FESEM) and X-ray diffraction (XRD) techniques. The C₆₀NRs were covalently immobilized on the surface of a glassy carbon electrode (GCE) using surface bound diazonium salts as an interface. This method involves electrografting of the p-nitrophenyl diazonium salt at the GCE to give the nitrophenyl-modified electrode (GCE–Ph–NO₂). The nitrophenyl groups of the GCE–Ph–NO₂ modified electrode were reduced to phenylamine groups (GCE–Ph–NH₂) using an aqueous solution of the sodium borohydride/gold–polyaniline (NaBH₄/Au–PANI) system. The C₆₀NRs were covalently immobilized on the surface of GCE–Ph–NH₂via an N–H addition reaction across the π-bond of C₆₀. The functionalized fullerene nanorod (C₆₀NRs–NH–Ph–GCE) modified electrode was electrochemically reduced in 1.0 M potassium hydroxide (KOH) to produce a highly conductive electrochemically reduced fullerene nanorod (ERC₆₀NRs–NH–Ph–GCE) sensor. The developed sensor shows high electrocatalytic activity for the detection of ethylparaben (EP) over a concentration range from 0.01–0.52 μM with a detection limit (LOD) of 3.8 nM (0.0038 μM). In addition, the ERC₆₀NRs–NH–Ph–GCE sensor was also tested for EP in real sample analysis using the standard addition method where the total concentration of EP was found to be 0.011 μM (0.12%) within the permissible limit of 0.19%.