A Coupled Flow Injection‐Capillary Electrophoresis System for Kinetic Study of Aspirin Hydrolysis in Aqueous Solution

Abstract 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.