Experimental Study On The Purification Of Artemisinin By Supercritical Fluid Chromatography

As the only internationally recognized antimalarial medicine of China, artemisinin is a kind of high-added-value and effective ingredients in drugs against malaria and cancer. However, many problems exist in the traditional separation and purification technology for artemisinin, such as the low efficiency of extraction, complicated steps, high consumption in solvent, and high solvent residues in product. So it couldn't realize the green and clean producing.Supercritical fluids have gas-like properties in terms of low viscosity and high diffusion, and at the same time, their densities and solvency are similar to those of liquids. Supercritical fluid extraction (SFE) and supercritical fluid chromatography (SFC), which are environment-friendly and high-efficiency separation and purification technology in the chemical engineering, just make use of the special properties of supercritical fluids. They have been widely used in the extraction and refining of nature drugs and food. In this paper, SFC is introduced into the purification of artemisinin from the Artemisia annua L. extraction solution for the first time.Methanol, ethanol, ethyl acetate and n-hexane were respectively used as the cosolvent in the SFE Artemisia annua L.. SC-CO2/ethyl acetate was chosen as the extractant by experiment results and appropriate extraction time was determined as 2.5 hours. Extraction Artemisia annua L. by the above-mentionded method, the extraction yield was 2.06 times of the result which just using pure SC-CO2 as the extractant.In the SFC purification and preparation for artemisinin, nonpolar column Zorbax SB-C18 (9.4×250mm I.D., 5μm) was used as the stationary phase, and SC-CO2 was used as the mobile phase. The velocity of CO2 and its impact on the resolution of the artemisinin and neighboring peaks were investigated, and besides, the impacts of pressure and temperature on the capacity factor of artemisinin and resolution were also studied. Eventually, the best conditions for chromatographic purification and preparation were determined: velocity of CO2, 22g·min-1; temperature of column, 313.15K; pressure of column, 11Mpa; quantity of sampling, 0.05mL; UV detector wavelength, 203nm. The Artemisia annua L extraction solution was purified under the above conditions and the content of 74.825% (wt%) crystal artemisinin could be gained.The study on the law of the retention in the SFC purification and preparation artemisinin process has been done. At last, basing on the experiment value of the capacity factor of artemisinin, the mean-field lattice model and MATLAB programming were used to obtain the parameters in the model. Moreover, the capacity factor of artemisinin was correlated with the density and temperature in SFC purification process. The correlation formula is as follows:The comparison of capacity factors of artemisinin predicted by the model and the experimental data indicates that, the calculated and experimengtal data are in good agreement and with a AARD% of 6.002%. It has shown that in the SFC purification process which SC-CO2 was used as the mobile phase, the law of the capacity factor varying the density and temperature could be preferablely described by the above model.