| Along with the overage use of synthetic chemistry pesticides, there appear many negative impacts out of expect. The pests and pathogens have resistant to pesticides through natural selection; at the same time produced severity contaminated to environment; and the residue of pesticides in food is a threaten to the life and health of people. So many countries all over the world devoted to develop bio-pesticides. Neem (Azadirachta indica, A. Juss) pesticides are a plant original bio-pesticide, which have the best potential in development. Azadirachtin is the main activity chemical in neem, the structure and ability as an insecticide has got embedded research. It has proved that azadirachtin have antifeedant, deterrent, growth-disrupting, anti-ovipositional, fecundity-reducing properties on nearly 400 species fanning, forest, storage and healthy insects which belong to 8 orders (lepidopterous, homoptera, dlptera, coleoptera, thysanoptera, hymenoptera, orthoptera, acarina).Neem pesticide is environment friendly and no residue in environment. It is safe to beneficial organisms, and no harm to human and mammals. And the extracts of neem have cure and prevention effects to the fungi and bacteria diseases and viruses of plants.Neem seeds kernels is the main material in azadirchtin extraction, by reason of there are high concentration of azadirachtin in it. Many methods of extract azadirachtin have reported, but they were aim in get the high purity azadirachtin, so the methods cannot use as the procedure in neem pesticides production. Although there are some patents in extract azadirachtin out of state, but also have some disadvantages. So this research select excellent soak and extraction solvent in azadirachtin extract procedure. The procedure is:After get rid of oil from neem seed kernels powder using hexane, extract azadirachtin using methanol; the methanol extraction is extract by the mixture solvent of CCl4 and petroleum ether to get rid of a great deal of non-polarity substance; Subsequently extract azadirachtin using ethyl acetate, later through silica gel cnromatography to remove the polarity substance in the extract, for instance, glucide and proteins et. al; so get the high azadirachtin concentration extraction. And found that the azadirachtin extraction treatment with hexane can turn dry rapidly, and get the dry straw yellow powder accordingly. The content of azadirachtin in the powder, which quantified by HPLC, is 21.3%. This azadirachtin production has good physical character and high azadirachtin content, so suit to the neem pesticide preparation. The production radio of this AZ product is 0.76%, amount to the azadirachtin product radio 0.17%. Estimated the cost of produce one tonazadirachtin dry powder is 463,800-657,000. This AZ extraction method is better than the extraction method of Sandaram on the cost And in Sandaram extract 1t AZ dry powder would cost 1,252,000-1,773,500. So this method is an low cost. Farmers could accept this cost of it.The content of azadirachtin is always as the standard in neem pesticide productions. But the productions are vast differentia in insecticide activity. The reason is that the azadirachtin related limonoids in the azadirachtin productions have the same insecticide activities. A method, which using colorimetric method determination the contents of limonoids in neem seed kernel extracts, is developed in this research. Optimize the factors in the colorimetric method, so get the colorimetric wavelength (517nm) and the concentration of vanillin solution (20mg/ml) of the method is as same as in Jianming Dai' method. And the volume of concentrated sulfuric acid (0.9ml), reaction time (10min) and reaction solution volume (expand to double volume) is different of Jianming Dai' method. The azadirachtin production was determined using this method, and the content of limonoids (include azadirachtin) is 81.35%. Obviously, the activity chemicals in the azadirachtin production are very high. The method can determine the content of limonoids in neem seeds extracts. |
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