Abstract: A developed high performance liquid chromatography (HPLC) method was introduced to determine the isomers of β-carotene. As a ternary solvent system of methanol-methyl t-butyl ether (MTBE)-water (50:45:5, V/V/V) was used as mobile phase, at lesat eight products of β-carotene melts were resolved within 10 mins with a C30 column of 1 ml/min flow rate at 455nm detection. Then these products were determined as possible isomers of β-carotene with the help of HPLC-APCI- MS. They are identified in the order, 15-cis-, 13-cis-, 9,15-di-cis-, 9,13-di-cis-, all-trans-, 13,15-di-cis-, 9-cis- and 9,13’-di-cis- β-carotene on the bases of spectral characteristics and Q ratios.

Key words: &beta, -carotene； isomer； C30； HPLC； APCI-MS；