Pesticidal dry powder formulation

摘要

The invention relates to a preparation of azadirachtin, in a dry solid powder form, having a purity upto 88%; an emulsion concentrate having upto 30% by weight of azadirachtin, and a process for preparing said azadirachtin dry powder from neem seeds/kernels, which comprising: (a) disintegrating the neem seeds/kernels into a powder; (b) subjecting the said powder to continuous extraction using methanol or aqueous methanol or ethanol (rectified spirit) or aqueous ethanol at ambient temperature; (c) concentrating the extract and stirring the concentrate with petroleumether or hexane and phase separating by conventional methods; (d) stirring the denser phase containing major quantity of azadirachtin with a water immiscible organic solvent and water as required depending on the solvent used for extraction and phase separating by conventional methods; (e) concentrating the organic phase and gradually adding the concentrate to petroleumether or hexane under stirring at ambient temperature (f), filtering under suction and drying under vacuum at a temperature in the range of 25 DEG -65 DEG C. to obtain a neem seed/kernel extract as a powder having azadirachtin of 10-19% purity; (g) redissolving the product obtained in step (f) in a solvent and adding the solution to petroleumether or hexane at ambient temperature gradually under stirring yielding a white solid, which after filtration and drying under vacuum at 65 DEG C. resulting in azadirachtin having 15-26% purity as a white powder (h), dissolving the azadirachtin (10-19%) from step (e) in an organic solvent and subjecting to column chromatography silicagel) by stepwise elution using different compositions of hexane/petroleumether and ethylacetate leading to solid azadirachtin powder upto 49% (i) dissolving the azadirachtin having upto 49% purity in methanol, ethanol or acetonitrile and subjecting it to HPLC (C18 column) to produce azadirachtin of purity upto 88% in a solid powder form, and (j) and stirring the product of step (i) with solvents and emulsifiers with or without synergist and UV stabiliser to obtain the emulsifiable concentrate.