The myrosinase cleavage of glucosinolates yields thioglycosidic compounds that show cancer chemoprevention. Glucosinolates occupied about 5% of the oil-pressed residue of rapeseeds. The present study describes the separation of 3-butenyl-glucosinolate (G1) and 2-hydroxy-3-butenyl-glucosinolate (G2) from the extract of the oil-pressed residue of rapeseeds by using slow rotary countercurrent chromatography (SRCCC) with a solvent system composed of n-butanol-acetonitrile-10% (NH4)(2)SO4 water solution (1:0.5:2, v/v/v). The separation of 50 g crude extract by a SRCCC instrument equipped with a 22 L column yielded 0.91 g of 1 and 3.57 g of 2 in 37.5 h. The purity of the two compounds was more than 95%, determined by HPLC. The structures of compounds I and 2 were identified by ESI-MS, H-1 NMR and C-13 NMR. (C) 2007 Elsevier B.V. All rights reserved.