A coupled flow injection-capillary electrophoresis system for kinetic study of aspirin hydrolysis in aqueous solution

A coupled flow injection-capillary electrophoresis (FI-CE) system was developed for automated determination of rate constants of chemical reactions. The system consists of a probe for sampling, a knotted reactor for on-line quenching reaction, an injection valve in combination with a split-flow interface for on-line electrokinetic injection; and a CE unit for separation and detection. Aspirin was used as a model compound to validate, the performance of the. coupled system. Under the optimized conditions, the coupled system achieved a sampling rate of 20 per hour, and a RSD of 1.1% for 25 consecutive determinations in 75 min. These features of the coupled FI-CE system allowed it to monitor reactions with half-reaction time being no less than 15 min. Several rate constants of aspirin hydrolysis in slightly alkaline media were determined with the developed system.