SEPARATION AND PURIFICATION OF AZADIRACHTIN FROM NEEM OIL
博士 === 國立臺灣科技大學 === 化學工程系 === 99 === Neem oil contains many bioactive compounds that are classified as limonoids. Neem limonoids have been known to possess insecticidal properties and have been proven effective in controlling various insects and pest. Separation and purification methods of azadirach...
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| Format: | Others |
| Language: | en_US |
| Published: |
2011
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| Online Access: | http://ndltd.ncl.edu.tw/handle/46880241942832373136 |
| Summary: | 博士 === 國立臺灣科技大學 === 化學工程系 === 99 === Neem oil contains many bioactive compounds that are classified as limonoids. Neem limonoids have been known to possess insecticidal properties and have been proven effective in controlling various insects and pest. Separation and purification methods of azadirachtin and other related limonoids from neem oil were developed in this research. Azadirachtin as the most important bioactive compounds in neem oil was used as the indicator of separation efficiency.
Separation of limonoids via hexane induced precipitation was capable of producing limonoids powder from crude neem seed oil. Precipitation yield is affected by ratio of hexane to oil, temperature, and precipitation time. The azadirachtin content in the limonoids powder obtained was increased up to 180-fold from its initial content in crude neem seed oil. The recovery of azadirachtin in the limonoids powder is 80% - 94%. The limonoids produced is in the form of fine powder with a volume mean diameter of 280 nm. Particles with irregular shapes were produced in this method as the result of rapid precipitation of limonoids powder.
Azadirachtin in the limonoids powders obtained were enriched further using silica gel column chromatography. Mobile phases which include ethyl acetate-hexane and toluene-methanol were investigated to obtain optimum separation efficiency. Two steps chromatographic separation were performed to produce high purity azadirachtin purity. From the first step chromatography, azadirachtin can be purified up to 4-fold with a corresponding recovery of around 50%. The second step chromatography failed to increase azadirachtin purity further. Very close polarity among limonoids obtained from the first step chromatography makes further separation of individual limonoids impossible by using silica gel chromatography.
Separation of limonoids from ethyl acetate was investigated via antisolvent crystallization method. Hexane was selected as the antisolvent to crystallize limonoids from ethyl acetate. Crystallization yield depends on the ratio of hexane to ethyl acetate and composition of limonoids powder. Limonoids powder can be crystallized from ethyl acetate with a crystal percentage of 77% - 99%. Azadirachtin purity can be increased slightly with corresponding recovery of 65% - 99%. Rapid crystallization of limonoids powder occurred under all crystallization conditions resulting in the formation of fine crystals with irregular shapes.
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