Supercritical anti-solvent micronization of chromatography purified marigold lutein using hexane and ethyl acetate solvent mixture

•The SAS technique was employed for micronization of purified lutein from marigold.•The mobile phase, hexane:ethyl acetate mixture, was used as solvent in SAS process.•The reduction of mean particle size was observed by increasing SC-CO2 flow rate.•The increase in pressure showed significant effect on particle morphology.•Aqueous solubility of the micronized lutein was found to increase significantly.

This work aims to study supercritical anti-solvent micronization of marigold derived purified lutein that was dissolved in the mixture of hexane and ethyl acetate (70:30 v/v), the solvent used as the mobile phase for chromatographic purification. The results show significant effect of pressure on the morphology of micronized lutein particles. The increase in lutein initial concentration from 1.5 mg/ml to 3.2 mg/ml and the increase in SC-CO2 flow rate from 15 ml/min to 25 ml/min show no significant effects on the morphology of lutein particles. However, the reduction of mean particle size from about 2 μm to 0.8 μm was observed by increasing SC-CO2 flow rate. The X-ray diffraction patterns of the micronized lutein particles show apparent amorphous nature, while the Fourier transform infrared spectroscopy results show that no chemical structural changes occurred. Moreover, the solubility of the micronized lutein particles in aqueous solution was found to increase significantly from being almost insoluble to having approximately 20% solubility

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