Dynamic modeling of electrophoretically mediated microanalysis

A dynamic model is presented for simulation of reaction-based chemical analysis of enzymes and substrates in capillary electrophoretic systems by the methodology of electrophoretically mediated microanalysis (EMMA). The mathematical model utilizes mass balance expressions describing the time-dependent effects of electromigration, chemical reaction, and diffusional band broadening upon the concentration profiles of the various reagent and product species. The model is implemented in an iterative computer program in which the capillary is segmented into arrays of bins storing the concentration profiles of each of the chemical species. During each time increment, the effects of electrophoresis, reaction kinetics, and diffusion are calculated, and the concentrations stored in the arrays are updated. The flexibility of the model to accommodate various initial capillary conditions, sample introduction methods, and voltage programming allows diverse EMMA analyses to be simulated. The simulated results are shown to be in good qualitative agreement with experimental data for zonal injection and moving boundary EMMA determinations of leucine aminopeptidase as well as an EMMA analysis of ethanol.