A sensitive electrochemical sensor with sulfonated graphene sheets/oxygen-functionalized multi-walled carbon nanotubes modified electrode for the detection of clenbuterol

A novel electrochemical sensor was designed to determine clenbuterol by using a new hybrid nanomaterials of water-dispersible sulfonated graphene sheets (SGSs) and oxygen-functionalized multi-walled carbon nanotubes (MWCNTs-COOH) modified glass carbon electrode (GCE). The π–π stacking interaction between SGSs and MWCNTs-COOH was verified by UV–vis spectroscopy, fourier transform-infrared spectroscopy and scanning electron microscopy. The anodic peak current (Ipa) of clenbuterol at the GCE modified with SGSs/MWCNTs-COOH was much higher than those at the bare GCE, SGSs/GCE and MWCNTs-COOH/GCE due to the synergistic effect of the modified nanomaterials. Differential pulse voltammetry disclosed a good linear relationship between Ipa and concentrations of clenbuterol (0.01–5.0   μM), with the detection limit of 4.6   nM. Finally, the modified electrode was successfully used to determine clenbuterol in liver samples.