Separation of azadirachtin and other limonoids from crude neem oil via solvent precipitation

Separation of azadirachtin and other limonoids from neem oil was carried out using solvent induced precipitation method. Hexane was chosen as the solvent due to its low polarity that can precipitate the more polar limonoids compounds from neem oil. The effects of solvent to oil ratio and temperature were investigated to determine optimum conditions for precipitation. Two different crude neem oils with initial azadirachtin content of 0.1% (oil A) and 0.04% (oil B) were used as the starting material. The final products obtained were fine powders that contain azadirachtin and other limonoids. Optimum recoveries for azadirachtin were 83.15% for oil A and 96.77% for oil B. Azadirachtin purities in the powders were 14.85% and 7.34%, respectively, which represented more than 180-fold enrichment from initial content in neem oils. The results suggested that hexane induced precipitation is a potential pre-concentration step in the separation of azadirachtin and other limonoids from neem oils.

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