Effect of pressure and temperature on extracting and crystallizing Andrographolide by using supercritical CO₂

The supercritical CO₂ extraction, crystallization, separation and purificntion of Andrographolide was conducted using Andrographis Paniculata Nees as raw material. The effects of pressure and temperature on extracting purity and crystallizing amount of Andrographolide were studied (purity of andrographolide 30% and 98%) in supercritical CO₂. The results showed that there appeared gradient distribution of crystallization of purity from downside to upside of crystal board; when the pressure is less than 25 MPa, the higher the pressure, the purer the crystal of upside of crystal board. While the pressure increases, the purity and the mass of crystal of downside of the crystal board became higher first, then lower; when the temperature increases, the purity of crystal became higher first, then lower, but to some extent, the higher temperature of extraction and crystallization could improve crystal purity, especially could shorten time of crystallization.