A chemical analytical method for quantitative determination in hydroxyethyl group of hydroxyethyl β cyclodextrin is proposed. The method consists of reacting hydroxyethyl β cyclodextrin with HI in the presence of catalyst on heating to form the corresponding amounts of ethene and iodoethane. Then react these compounds with bromine to give I 2, which can be easily determined by standard hyposulphite solution. The formulas for calculation of the average substitution degree from titration results are described. The results obtained by this method appeared to be more accurate than those based on 1H NMR method.
