Capillary electrophoresis of oligonucleotides: micellar system or entangled polymers

The capillary electrophoretic separation of oligonucleotides (12-24 bases in length) using a micellar system or an entangled polymer solution was compared. Micellar electrokinetic capillary chromatography was performed using a fused-silica capillary whereas a J&W DB-17-coated capillary was used for capillary electrophoresis in entangled polymer solution. In both cases, a number of parameters were evaluated to improve separation. For example, the influence of concentration of copper(II) ions and sodium dodecyl sulfate, variation in applied voltage and temperature were investigated in the micellar system. The influence of variation in pH was also studied. The two methods were also compared with respect to their efficiencies. The results of quantitation showed better within-day and day-to-day repeatability for the entangled polymer solution. Both methods gave a comparable limit of detection of about 30 pg at a signal-to-noise ratio of 3.