Comparative quantitative analysis of artemisinin by chromatography and qNMR

Introduction - Since the discovery of artemisinin in the 1970s, many techniques based on diverse chromatography techniques have been developed to detect and quantify this important antiplasmodial compound. The accurate quantification of this compound in the Artemisia annua plant material is mainly needed for breeding purposes in order to cultivate higher yielding varieties. It is also important for the quality control of herbal preparations containing A. annua plant material. Objective - To evaluate the most common validated quantification techniques (LC-MS, HPLC-ELSD and TLC) and compare the results to quantitative nuclear magnetic resonance spectroscopy (qNMR) in eight different A. annua samples collected from around the world. Methodology - The leaf material were extracted according to standard procedures and analysed with the validated quantification techniques. For the qNMR analysis we did not employ a standard curve but instead used an internal standard (maleid acid) which is not chemically related to artemisinin. Results - We found a significant difference between the results in this study. Compared with the qNMR results the HPLC-ELSD corresponded closely, followed by LC-MS. Quantitation with TLC led to an estimation range of -0.5 to +3.2 mg artemisinin/g of A. annua. Conclusion - These results imply that qNMR, with the addition of an internal standard, can be used to quantify artemisinin in A. annua samples in a rapid and reproducible manner.