A microfabricated fluidic device for performing two-dimensional liquid-phase separations

A microfabricated fluidic device that combines micellar electrokinetic chromatography and high-speed open-channel electrophoresis on a single structure for the rapid automated two-dimensional analysis of peptides has been devised and demonstrated. The microchip operates by rapidly sampling and analyzing effluent in the second dimension from the first dimension. Second-dimension analyses are performed and completed every few seconds, with total analysis times of less than 10 min for tryptic peptides. The peak capacity of the two-dimensional separations has been estimated to be in the 500-1000 range. The orthogonality of the separation techniques, an important factor for maximizing peak capacity or resolution elements, was verified by examining each technique independently for peptide separations. The two-dimensional separation strategy was found to greatly increase the resolving power over that obtained for either dimension alone.