Integrated CE chip - concentration and high-resolution cyclic CE technology

Single column transient isotachophoresis (TITP) system and cyclic CE chip is integrated on PDMS (polydimethylsiloxane) chip. ITP part can concentrate low concentrated sample by over the 500-folded times. In addition, as additional coating of EOF modifier, the velocity and resolution is improved. The focusing of sample and separation is processed in a single column. The TITP chip has the disadvantage of low resolution, because it has the limited channel length with a limited voltage for a general CE chip. So, the focused sample was separated in the cyclic CE. The focused high concentration sample became the plug of the cyclic CE. Cyclic CE, which is the one of the channel network structures, has advantages in downsizing and a low operation voltage. However, there are some problems such as sample loss when the injected plug encounters the junctions in the middle of the channel. This paper will show the optimum design that these problem was considered. By a dyestuff experiment, the procedure of focusing step and separation are observed and studied. All these procedure is operated by just E-field. The chloride ion is used as the leading electrolyte, and the volume of injection is about 20 μL. Under our LIF conditions, the sample concentrated over the 500-folded times and cyclic CE chip showed < 2 % degradation per junction. This means the high resolution CE analysis has 100,000 plate numbers after a three and one quarter cycle in just 3.5 × 6 cm chip.