The upper figure (A) represents the GC chromatogram of silylated linseed oil sterols : 1: brassicasterol; 2: 24-methylene campesterol; 3: campesterol; 4: stigmasterol; 5: β-sitosterol; 6: ∆5-avenasterol; 7: cycloartenol; 8: ∆7-stigmasterol; 9: ∆7-avenasterol; and 10: betulin (internal standard); the B part mass spectrum of the cycloartenol at the retention time (RT) 12.58.