Miniaturization of sampling for chemical reaction monitoring by capillary electrophoresis

Purpose-made capillary electrophoresis set-ups for reaction kinetics monitoring featuring two automated injectors allowed the easy reduction of the needed reactant amount down to 500 microL. The first set-up is similar to the cross injector used frequently in lab-on-chip designs while the other uses falling droplets for sample/buffer delivery. The versatility of the system was demonstrated by the analysis of oxidation of C-vitamin by hydrogen peroxide. Pseudo first order reaction rates about 10(-3) s(-1) were measured with RSD = 1-3% in one experiment and RSD = 20% in interday/person experiment. Plate numbers were typically around 5000-20,000.