New principle of electromagnetophoretic adsorption–desorption microchromatography

A new principle for the chromatographic micro-separation of micrometer-sized particles in liquid has been invented by switching the electromagnetophoretic force in a capillary flow system. The principle is the combination of the Stokes force by the bulk flow and the adsorption–desorption force on a capillary inner surface controlled by an electromagnetophoretic buoyancy generated by an alternative current and a homogenous magnetic field. The observed retention profiles of test micro-particles was explained by the “zigzag” migration model mainly depended on particle size and their adsorption force to the capillary wall. By this method, we could succeed to separate polystyrene particles of 10 μm and 20 μm in diameter dispersed in 1 M KCl solution containing 0.01% Triton X-100 using only 1 mm long fused-silica capillary under 10 T.