Abstract: The volatile oils of 23 Ligusticum chuanxiong Hort. samples from 4 different regions were analyzed by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC/TOF MS). The group-type separation of 4 terpenoids and phthalides was well accomplished based on a DB-Petro×DB-17 column system. With the MS library search, 215 compounds were tentatively identified based on the NIST database and the 43 compounds of them were confirmed by using the retention index or comparing with the standard compounds in a typical sample from Xindu City. Twenty three samples were apparently classified into 4 groups by partial least square-discriminant analysis. A brief list of 20 differential compounds is presented, including cnidilide, 3-n-butylphthalide and butylidene phthalide. DPPH (1,1-diphenyl-2-picrylhydrazyl) stable free radical scavenging assay was adopted to differentiate the antioxidative potency of these samples, which was expressed as EC50. Based on the orthogonal partial least square model the biochemical discrimination of samples was achieved with ligustilide, senkyunolide A and neocnidilide as important differential compounds according to geographical origins. All the results indicated that phthalides exert a great influence on the chemical and biochemical classifications of Rhizoma Chuanxiong, and the samples from Pengzhou City have the highest contents of phthalides.

Key words: Ligusticum chuanxiong Hort. , phthalide, quality control, volatile oil, comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC/TOF MS)