Non-orthogonal-to-the-flow electric field improves resolution in the orthogonal direction: hidden reserves for combining synthesis and purification in continuous flow.

There is a pressing need for continuous purification of products of synthesis conducted in continuous-flow microreactors. An existing technique, micro free-flow electrophoresis (microFFE), could fulfill this niche if its resolving power for similar molecules was improved. MicroFFE continuously separates ions in the hydrodynamic flow by an electric field orthogonal to the flow. Here, we prove theoretically from first principles that the resolving power of microFFE can be greatly improved by the use of a nonorthogonal to the flow field. This result may be decisive in starting practical attempts to combine synthesis in continuous-flow microreactors with continuous-flow purification by microFFE.