Air/light-free hyphenated extraction/analysis system: supercritical fluid extraction on-line coupled with liquid chromatography-UV absorbance/electrospray mass spectrometry for the determination of hyperforin and its degradation products in Hypericum pertoratum

Hyperforin, which is a major active constituent of the antidepression herbal medicine-Hypericum pertoratum (St. John's wort), is very sensitive to oxygen and light. Our paper reports for the first time an air/light-free extraction-separation-detection hyphenated system and its application to St. John's wort. It involves on-line coupling of supercritical fluid extraction with liquid chromatography-UV absorbance/electrospray ionization mass spectrometry (SFE-LC-UV/ESI-MS). Mass spectral data on the extract that was produced on-line suggested the presence of the major degradation compound of hyperforin-furohyperforin and two of its analogues. Thus, some degradation process must have already occurred in our sample during plant drying or storage. The feasibility of quantitative extraction and analysis of hyperforin by on-line SFE-LC was made possible by optimizing the extraction pressure, temperature, and CO(2) modifier content. High recovery ( approximately 90%) relative to liquid-solid extraction was achieved under optimized conditions.