In pH 2.9～4.6 Britton-Robinson (BR) buffer solution, the hydrolyzed product of colchicine was reacted with some acid sulfonephthalein dyes such as bromophenol blue (BPB), bromocresol green (BCG), bromothymol blue (BTB) and thymol blue (TB) etc. to form ion-association complexes. As a result, the resonance Rayleigh scattering (RRS) was enhanced greatly, and a new RRS spectrum appeared. The maximum RRS signals of four ion-association complexes are located at 327, 311, 305 and 306 nm, separately. The intensities of RRS are proportional to the concentration of colchicine. And the detection limits for colchicine are 12.3, 15.1, 16.4 and 20.0 ng•mL－1, respectively. The optimal conditions and the effect factors of the reaction were investigated. A more sensitive, simple and fast method for the determination of colchicine based on the RRS technique has been developed, which was applied to determination of colchicine in tablet, hemerocallis, serum and urine samples with satisfactory results.

Key words: resonance Rayleigh scattering, colchicine, acid sulfonephthalein dye