Selectivity in electrophoretically mediated microanalysis by control of product detection time.

Differential electrophoretic mobility between an analyte and its product offers electrophoretically mediated microanalysis (EMMA) a unique capability to selectively control the detection time of the product of a reaction-based chemical analysis. If an analyte and its product differ in migration velocity under the influence of an applied electric field, the apparent velocity and, consequently, the detection time of the product are dependent upon the relative amounts of time the product effectively traverses the capillary with the respective mobilities of the analyte and the product. Consequently, by controlling when the analytical reaction is allowed to occur, the detection time of the reaction product can be selectively maneuvered within a time window defined by the mobilities of the analyte and the product. This paper describes the use of this technique to manipulate the detection time of product profiles independently of nonreacting matrix interferants for the determination of both enzymes and substrates by EMMA. Furthermore, the ability to manipulate product detection times allows for simultaneous EMMA determinations of multiple enzymes or substrates.