The determination of bromide in a local anaesthetic hydrochloride by capillary electrophoresis using direct UV detection.

The determination of residual amounts of bromide in a local anaesthetic hydrochloride by capillary electrophoresis was developed. Direct UV detection at 200 nm was used for the determination of the bromide content. The separation capacity of the system must be sufficient when bromide is determined in the presence of a large excess of chloride since electromigration dispersion of the highly concentrated chloride peak may impair the resolution. The background electrolyte (BGE) contained both acetonitrile and methanesulphonic acid in order to improve the selectivity and minimise the electromigration dispersion. The system was optimised with respect to resolution of the chloride and the bromide peaks by statistical experimental design using a multivariate optimisation program. The developed method was validated in accordance with the ICH guidelines and proved to be suitable for its intended use.