Macrofluidic Device for Preparative Concentration Based on Epitachophoresis

We have developed a new separation device to concentrate and collect ions from several milliliter sample volumes to microliter fractions. Unlike most conventional platforms, this device has circular architecture. The electrophoretic migration operates from the outer perimeter toward the center. Separations can be performed both in continuous (zone electrophoresis) and discontinuous (moving boundary) electrolyte systems. We use a discontinuous electrolyte system comprising a leading and a terminating electrolyte to concentrate samples containing small organic anions and DNA fragment. The agarose gel stabilizes the boundary between the leading and terminating electrolytes. The milliliter volume sample is mixed with the terminating electrolyte and migrates through the gel toward the center. The concentrated total sample is collected in microliter fraction at the center. The potential for preparative concentration of DNA is demonstrated using a DNA ladder. Because zone migration accelerates as it moves toward the center, we named this method Epitachophoresis from the Greek word (epitachyno), meaning acceleration. To the best of our knowledge, this unique circular architecture has not been previously described.