Combination of flow injection with capillary electrophoresis. Part I. The basic system

A combined flow injection (FI)-capillary electrophoresis (CE) system was developed using conventional FI and CE equipment. A flow-through reservoir equipped with a conical inlet was used as an interface to connect the FI system to the capillary inlet. A grounded electrode was inserted in the reservoir. Split-sampling was achieved in the electrokinetic mode when an injected sample zone in the microliter range was transported into the conical inlet by a carrier solution which also served as the separation buffer. Using benzoic acid as a model the combined system demonstrated significantly improved precision in peak height, peak area, and migration time as compared to conventional manual electrokinetic sample introduction while achieving similar sensitivity and column efficiency. Using a test sample containing magnolol and benzoic acid, a series of samples was injected continuously without current interruption, achieving sample throughputs at least three times higher than conventional CE sample introduction.