Development of HPLC analytical protocols for quantification of artemisinin in biomass and extracts

The impact of impurities in various crude A. annua extracts on the analysis of artemisinin by liquid chromatographic methods

“…For this purpose, analysis of artemisinin has been undertaken using high performance liquid chromatography (HPLC) with ultraviolet detection (-UV) [9][10][11][12][13], evaporative light scattering detection (-ELSD) [12,14] and refractive index detection (-RI) [11]. In addition, thin layer chromatography (TLC) [15], nuclear magnetic resonance (NMR) [10,16], liquid chromatography -mass spectrometry (LC-MS) [10,17], and gas chromatography with both mass spectrometry (GC-MS) [18] and flame ionisation detection (GC-FID) [14] methods have been developed, among others.…”

“…The important evaluation of different analytical methods for the quantification of artemisinin in crude leaf extracts made by Lapkin et al [11], and funded by Medicines for Malaria Venture (MMV), was necessary because the HPLC-UV method given in the WHO Monograph and the International Pharmacopoeia cited by Lapkin et al [11] is intended for the analysis of API or starting materials. Many researchers maintain that the lack of a chromophore for artemisinin makes UV detection unsuitable [9,12,16,19].…”

“…The study by Lapkin et al [11] examined a UV range of between 205 and 215nm and determined the maximum absorbance in this range to occur at 210nm.…”

“…It has been suggested that HPLC-UV analysis is inappropriate for crude artemisinin extracts as the peak response can be difficult to detect among highly-absorbing impurities [11]. This conclusion was supported by a chromatogram of an ethyl acetate extract but the chromatograms for the hexane, acetonitrile or chloroform extracts were not presented.…”

“…As no reference to pure ethyl acetate extractions can be identified in the literature and acetonitrile would be unacceptably hazardous to use on a large scale [1], these findings do not necessarily invalidate HPLC-UV analysis of industrial extracts. The modified WHO Monograph method developed by Lapkin et al [11], hereon referred to as "Modified HPLC Protocol", was not applied to ethanol extracts and although a method does exist for their analysis it involves the prior derivatisation of artemisinin [9].…”