Preparation And Study Of Ache Enzyme Film For The Rapid Detection Of Organophosphorus Pesticide

With the development of modern agriculture, the pesticides, as an important tool against plant diseases and insect pests, have become an important part for agricultural productions. However, because of the uncorrected use, the pesticide residue has gradually become a huge obstruction which greatly impedes the development of the modern agriculture. Due to chemical stability, the degradation of pesticides is so slow that they are partly left in the environment and plants. The residue of pesticides is harmless to human body in less than a certain amount, but the accumulation in human and animal bodies can cause chronic poisoning.Organophosphorus pesticide is used widely in agriculture areas due to its low cost and high selectivity. In order to meet human health security and green agriculture, the detection of pesticide residues is important. Most of the methods including gas chromatography (GC), high performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS) and pesticide residues rapid measuring have advantages and disadvantages respectively.In order to solve the problems in rapid detection technology for pesticide residues, three parts were studied in this paper.1. A dipstick which is used for pesticide residues was prepared. In this part wheat esterase catalyzed indophenol acetate as substrate. Wheat was dissolved in buffer solution pH 6.98, and the color of solution was changed observably. Plant esterase was used to test malathion, and the result was judged through macroscopic colorimetric. A preliminary conclusion was got including the time of inhibition and response, the temperature and the concentration of substrate etc.2. A rapid and sensitive visual detection of methyl parathion in homogeneous reaction was developed using water soluble poly(vinyl alcohol) (PVA) to immobilize cholinesterase (ChE). When used, a piece of ChE-PVA film is put into the solution and dissolved quickly. The released ChE from enzyme film was mixed and interacted fully with substrates and methyl parathion inhibitors. The color reaction was developed quickly in homogeneous system and the change or difference of color could be observed easily and clearly, while for common colorimetric sticks or strips for pesticides, it is difficult to discern the difference of developed color exactly due to the uneven dying on the surface of supporting matrix. With 10 min of inhibition and 5 min enzyme reaction,0.1μg/mL concentration of methyl parathion could be observed by visual detection.3. Hydroxyapatite nanoparticles and hydrophilic ionic liquid were imported. The proportion of ionic liquids and hydroxyapatites was selected. Methyl parathion pesticide was detected through the enzyme film. The pesticide residue in lettuce was estimated by the above methods.Here, a novel technique of enzyme immobilization was developed using water soluble PVA as support matrix which is a rapid, sensitive and visual detection of organphosphorus pesticides.