Simultaneous determination ofSonchus arvensis L. triterpenes by gas chromatography-mass spectrometry.

Sonchus arvensis L. or sow thistle has proved an excellent source of pentacylic triterpenes; triterpenes account for about 6% of the crude lipid extract or 0.2% of the dried plant. Composition of the triterpenoid fraction, as indicated by gas chromatography of the corresponding acetates, was α-amyrin (9%), β-amyrin (21%), lupeol (13%), taraxasterol (24%) and pseudo-taraxasterol (12%). A single, long-chain alcohol (16%) was also present. The nature of the triterpenoids was defined using gas chromatography and gas chromatography-mass spectrometry (GC/MS) and confirmed by direct comparison with authentic samples. The use of combined GC/MS proved extremely valuable in the simultaneous analysis of a mixture of triterpene acetates and greatly reduced the time needed to phytochemically evaluate these compounds.