采用光电化学方法检测甲基对硫磷在番茄中的残留

Photoelectrochemical Method for the Detection of Methyl Parathion Residues in Tomato

通过原位合成方法,将石墨烯（G）和多元硫化物（Cd0.5Zn0.5S）杂合,成功制备了Cd0.5Zn0.5S/G纳米复合物。将Cd0.5Zn0.5S/G纳米复合物修饰在玻碳电极表面上,基于有机磷农药对修饰电极光电流信号抑制的原理,以甲基对硫磷作为模型分子,构建了有机磷农药甲基对硫磷的光电化学传感器。采用扫描电镜（SEM）和电子色散光谱（EDS）对Cd0.5Zn0.5S/G进行表征,并考察了Cd0.5Zn0.5S/G的光电化学性能,实验发现与单独的Cd0.5Zn0.5S和G相比,Cd0.5Zn0.5S/G纳米复合物的光电化学信号大大增强,这是由于Cd0.5Zn0.5S和G的杂合使得纳米复合物产生协同作用,从而提高了检测的灵敏度。用该传感器对不同浓度的甲基对硫磷进行检测,结果表明检测线性范围为0.01-100 ng/m L,检测下限为5 pg/m L。该传感器表现良好的稳定性和重现性,为有机磷农药的快速检测提供了一种有效的途径。

Cd0.5Zn0.5S/G nanocomposite was successfully prepared by the in situ aoping of graphene （G） with multi-metal sulfide （Cd0.5Zn0.5S）. The composite was used to modify the surface of a glassy carbon electrode. Based on the principle of suppression of photoelectrochemical signals by organophosphate pesticides, using methyl parathion as a model molecule, a photoelectrochemical sensor was constructed. The Cd0.5Zn0.5S/G nanocomposites were characterized by scanning electron microscopy （SEM） and electron dlspersion spectroscopy （EDS）, meanwhile, their photoelectrochemical performance in a buffer solution was also investigated. The result showed ttiat, because of the synergistic effect between Cd0.5Zn0.5S and G, the photoelectroehemical intensity of the Ca0.5Zn0.5S/G nanocomposites was significantly higher than that of pure Cd0.5Zn0.5S and G, thus increasing the sensitivity of the sensor. The constructed sensor was used to analyze methyl parathion solutions with different concentrations, and it exhibited a linear response to methyl parathion over a wide range, from 0.01 to 100 ng mL^-1, with a detection limit of less than 5 pg mL^-1. The sensor showed excellent reproducibility and stability, and provided an effective approach for the rapid detection of organophosphate pesticides.