A highly sensitive sensor for synephrine detection based on multi-walled carbon nanotubes modified glass carbon electrodes

A sensitive, fast and cheap sensor, based on a glassy carbon electrode (GCE) modified with a multiwalled carbon nanotubes (MWCNTs)/Nafion film, is reported for the quantitative determination of synephrine in the Chinese traditional herbal drug Pericarpium citri reticulatae using . The electrochemical behavior of synephrine at this sensor was explored in Britton–Robinson buffer solution using cyclic voltammetry. An oxidation peak at 1027 mV was observed for synephrine when a bare GCE was used, whereas an oxidation peak at 998 mV with greatly enhanced peak current was obtained at the MWCNTs/Nafion/GCE, showing the electrocatalytic nature of the modified electrode. Moreover, cyclic voltammetric studies indicated that the oxidation of synephrine at the modified electrode was irreversible, adsorption controlled and involved two electrons. A calibration plot of oxidation peak current versus synephrine concentration was linear in the range of 1 × 10−8 to 1 × 10−5 mol L−1. The detection limit of synephrine was found to be 8 × 10−9 mol L−1 by linear sweep voltammetry . The effect of pH and scan rate of synephrine were studied. This is currently the first report on the determination of trace synephrine by a purely electroanalytical method. The analytical performance of this sensor was also evaluated for the detection of synephrine in real samples.