An ultrasensitive electrochemical sensor based on in situ synthesized manganese dioxide/gold nanoparticles nanocomposites for rapid detection of methylmercury in foodstuffs.

The inclusion of methylmercury (CH 3 Hg + ) in the environment and food chain has aroused wide concern due to its high neurotoxicity and cumulative effects. Herein, a highly sensitive electrochemical sensor based on manganese dioxide (MnO 2 )/gold nanoparticles (AuNPs) composites is fabricated for CH 3 Hg + detection in food. The MnO 2 /AuNPs nanocomposites were synthesized in situ on the surface of a glassy carbon electrode by an electrodeposition method and were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The resulting MnO 2 /AuNPs modified electrode exhibited a large active surface area, enhanced conductivity and excellent electrocatalytic activity toward CH 3 Hg + due to the synergistic effect of MnO 2 and AuNPs. Square wave anodic stripping voltammetry (SWASV) was used as the sensing technique for CH 3 Hg + , and the stripping peak current showed a good linear relationship with CH 3 Hg + concentration in the range of 0.7-15 μg L -1 with a detection limit of 0.051 μg L -1 . Besides, the interference from Hg 2+ associated with CH 3 Hg + detection can be avoided by the addition of diethylene triamine pentaacetic acid (DTPA). The as-prepared sensor was applied to detect CH 3 Hg + in various food samples with satisfactory recoveries, thus providing a promising platform for rapid screening of methylmercury residues.