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

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%.