Quantitation of 20 Phytosterols in 34 Different Accessions of Quinoa (<i>Chenopodium quinoa</i>)
Sarah Schlag, Sören Götz, Felix Rüttler, Sandra M. Schmöckel, Walter Vetter
Abstract
Phytosterols were analyzed in 34 different quinoa accessions, which were obtained from the same field trial. Twenty different sterols were detected, and 17 could be structurally assigned by means of gas chromatography with mass spectrometry. Sterols were quantitated in selected ion monitoring mode (GC/MS-SIM) with the novel internal standard 3-O-tert-butyldimethylsilyl-cholestanol (cholestanyl-TBDMS). GC/MS-SIM response factors of minor sterols were determined after enrichment by countercurrent chromatography. The total sterol contents varied from 120 to 180 mg/100 g of seeds, which is higher than has been described in quinoa before. This was due to the fact that Δ7-sterols (e.g., Δ7-sitosterol, spinasterol, and Δ7-avenasterol) were quantitated for the first time in quinoa and contributed ∼64% to the total sterol content. Clustering allowed distributing of the 34 different quinoa accessions into four distinct groups on the basis of the different sterol patterns.