Studies On Fast Detection Of Organophosphorus Pesticides By An Enzyme-based Biosensor

With high efficiency of killing pests, the organophosphorus pesticide is one of widely used pesticides in the agriculture. However, due to the large scale of their application, the residua of organophosphorus pesticides had brought serious environment pollution which became a greater and greater threaten to the health of human beings at present. Conventional methods for detecting residual organophosphorus pesticides included chromatography, mass spectrometry, spectroscopy, et al., they were time consuming and costly, and were hard to satisfy the increasing requirements of the online detection. As a comparison, biosensors provided a promising way to detect organophosphorus pesticides which was both rapid and simple.In this paper, an enzymatic electrode biosensor was prepared by immobilizing acetylcholinesterase with the crosslinking agent named glutaraldehyde. The conditions of the making an enzymatic electrode, such as the concentration of glutaraldehyde and enzyme, were discussed. And then, different factors which had effects on working of enzymatic electrodes, for instance, the pH of destination solution and the temperature of the environment, were investigated. The optimum working conditions of enzymatic electrodes were ascertained. The stability of enzymatic electrodes were also tested. Based on the analysis of the mass transfer of hydrogen ion, it was proved that the agitation operation was negative as to the improvement of sensitivity of the biosensor.Dursban, a widely used organophosphorus pesticide nowadays in China, was choosed as the subject investigated. With the biosensor as mentioned before, the calibration curve, which has a quantitative determination range from 1.64 to 20.52ppm,was plotted.Other immobilization methods of acetylcholinesterase were also attempted in this paper. An injecting biosensor was also investigated. The preliminary result showed that it had the advantage of simplifying the replacement of enzyme membrane. However, the sensitivity of this biosensor still needed some improvement.The post treatment module of the biosensor included the amplification, sampling, displaying and storing of the analog signal. In this paper, the demand of the designation of the post treatment was carefully analyzed. The debugging of the hardware unit was completed, and, with Microsoft Visual C++ develop platform, the basic function of sampling software was implemented.