Qualitative and Quantitative Studies on Artemisinin with Raman Spectroscopy.

Artemisinin, one of the most powerful new generation antimalarial drugs, is an unique sesquiterpene lactone compound extracted from traditional Chinese drug Artemisa annua L, which contains specific endoperoxide bridge. In this study, the Raman scattering of artemisinin in the spectral range of 100～3 500 cm-1 has been investigated. The analysis suggests that the phonon mode at 724 cm-1 would be directly correlated with a representative vibrational mode of the ring containing endoperoxide bridge, thus it can be applied for Raman detection of endoperoxide bridge in artemisinin. The phonon mode at 1 734 cm-1 would be directly correlated with a representative vibrational mode of the lactone ring, thus can be applied for further identification of artemisinin with Raman spectroscopy. Also both of these two phonon modes can be easily observed by Raman experiment; therefore they are good representative phonon modes for quick qualitative analysis of artemisinin by Raman spectroscopy. In addition, by investigating the relative intensity ratio of the two representative phonon modes at 724 and 1 734 cm-1, the Raman method can be applied for quantitative analysis of artemisinin purity. Compared with the commonly used high performance liquid chromatography method, the Raman method is much more powerful: it is faster, more convenient, more accurate, and can be applied for the analysis of homogeneity of purity for artemisinin samples. Furthermore, the qualitative and quantitative analysis of artemisinin purity would be very helpful for quantitative analysis of the quality of Chinese drug Artemisa annua L with Raman spectroscopy.