Study On Detection Of Organophosphorus Pesticides Based On Electrochemical Sensor And Its Performance

Organophosphorus pesticides are widely used at present. They can irreversibly combines acetylcholinesterase(AChE) to inhibit the catalytic active sites of acetylcholinesterase in nerve-impulse transmission, which leads to nerve disease, even death. Therefore, how to detect the organphosphorus pesticides fast and effectively is a significant research task in analytical chemistry, and it is also a great challenge for analytical workers. Current analytical techniques gas chromatography/mass spectrometry(GC/MS) and high performance liquid chromatography(HPLC) are though accurate, but require pre-disposal, expensive instrumentation and highly trained personnel. Therefore, the rapid, highly sensitive, selective, and powerful methods for pesticides is essential that has the important practical significance to the environmental protection and food security.Biosensor can satisfy the requirement of rapid detection of organophrosphorus pesticides due to its high sensitivity, simple sample treatment, inexpensive instrument, and easily operation procedure. AChE electrochemical biosensor has been attentioned by study on detection of organophosphorus pesticides based on biosensors. However, the stable and sensitive of AChE electrochemical biosensor can not satisfy the requirement of detection recently, and its repetition shows not well.The properties of nanosturctured materials include great specific surface,high surface free energy,great adorsption and nanosturctured materials can link certain functional groups of biological molecule. The application of nanosturctured materials on electrochemical biosensor can promote sensitive and repetition of electrochemical biosensor, and is a promising area for new electrochemical biosensor.The aim of this study is to overcome the problems of electrochemical biosensor. Two novel electrochemical biosensors were constructed based on single-walled carbon nanotubes and gold nanoparticles:A novel bio-film has been fabricated with single-walled carbon nanotubes(SWNTs) and PDDA on the surface of the glassy carbon electrode by self-assembled method. The enzyme membrane was then fixed on the surface of the SWNTs-PDDA to build AChE/SWNTs-PDDA film. A novel stable AChE/DAR/AuNP/DAR film was fabricated at a glassy carbon electrode modified with DAR,gold nanoparticles and acetylcholinesterase by self-assembled method.The study proved that these two films can be used to detect organphosphorus pesticides. So these two films were modified at glassy carbon electrode to build novel AChE/SWNTs-PDDA/GCE electrochemical biosensor and AChE/DAR/AuNP/DAR/GCE electrochemical biosensor. And the prepared of the biosensor was optimized. The detection of organophosphorus pesticides(paraoxon) was studied by aperometric curve. The experiments proved that the SWNTs enhance the current response to paroxon and reduce overpotential of thioncholine. Under the optimized conditions, the response of the biosensor fabricated was related linarly to concentration of paraoxon in the range from 10^-6to 10^-10g/L at 0.20V with a detection limit of 10^-12g/L. AChE/DAR/AuNP/DAR/GCE electrochemical biosensor can reduce the preparation of electrode and overpotential of thioncholine, enhance the examination selectivity and sensitivity with ferrocenemonocarboxylic acid as the electronic mediator by compare with other solid electrodes. Its best conditions of the experiments were 30s of hv, 1 layer of DAR/AuNP, 7.5 of pH, 2 layers(10U) of AChE and 2mM of ATCl, its suitability for online and in-itu. The average absolute deviation of AChE/DAR/AuNP/DAR electrochemical biosensor was 3.71%. The enzyme film stabilizes no easy to remove and measure current stability.