High-sensitivity capillary gel electrophoretic analysis of DNA fragments on an electrophoresis microchip using electrokinetic injection with transient isotachophoretic preconcentration.

The research adopted a single-channel microchip as the probe, and focused electrokinetic injection combined with transient isotachophoresis preconcentration technique on capillary electrophoresis microchip to improve the analytical sensitivity of DNA fragments. The channel length, channel width and channel depth of the used microchip were 40.5 mm, and 110 and 50 microm, respectively. The separation was detected by CCD (charge-coupled device) (effective length=25 mm, 260 nm). A 1/100 diluted sample (0.2 mg/l of each DNA fragment) of commercially available stepladder DNA sample could be baseline separated in 120 s with S/N=2-5. Compared with conventional chip gel electrophoresis, the proposed method is ideally suited to improve the sensitivity of DNA analysis by chip electrophoresis.