EVALUATION OF THE UTILITY OF CAPILLARY ELECTROPHORESIS FOR THE ANALYSIS OF SULFOBUTYL ETHER BETA-CYCLODEXTRIN MIXTURES

A capillary electrophoresis (CE) method for the analysis of a sulfobut yl ether beta-cyclodextrin (SBE-beta-CD) mixture is described. The SBE -beta-CD has been prepared as a parenterally safe solubilizing agent a nd has historically been characterized by elemental analysis and nucle ar magnetic resonance spectroscopy. While these methods provide gross values for the degree of substitution, the CE method described resolve s the mixture of positional and regional isomers based on the degree o f SBE substitution. The method uses benzoic acid in the running buffer and detects the CD by a decrease in background absorbance of the benz oic acid due to complexation. The necessity of a defined column wash s equence between injections was evaluated. The reproducibility of migra tion times and peak areas/heights for 10 components of the mixture was determined. The modular CE system gave a relative standard deviation of 2.5% (n = 3) for six of the 10 peaks. Further refinements (pH buffe r effects) were explored to improve the reproducibility with remaining components. The method was used to evaluate the reproducibility of th e synthesis (21 different lots) and the effect of reaction variables ( time, temperature and base) on the composition pattern of the modified CD.