Sensitive and selective electrochemical sensor for magnolol based on the enhancement effect of multiwalled carbon nanotubes

Herein, insoluble multiwalled carbon nanotubes (MWNTs) were dispersed into N,N-dimethylformamide (DMF) via ultrasonication, resulting in a stable and homogeneous MWNTs suspension. After evaporation of DMF, the surface of glassy carbon electrode was successfully coated with MWNTs film, as confirmed from scanning electron microscopy measurements. In pH 7 phosphate buffer, an irreversible oxidation peak was observed for magnolol, and the peak currents greatly increased on MWNTs film surface. The influences of pH value, amount of MWNTs and accumulation conditions were studied. Based on the remarkable enhancement effect of MWNTs, a new electrochemical sensor with high sensitivity was developed for magnolol. The linear range was from 5 μg?L^?1 to 1 mg?L^?1, and the detection limit was 2 μg?L^?1 (7.51?×?10^?9?M) after a 3-min accumulation. This novel sensor was successfully used to detect the content of magnolol in Chinese traditional medicines, and the recovery was over the range from 98.1 to 99.1 %.