Study on Factors Affecting Reproducibility of Migration Time in Capillary Electrophoresis

The effects of running buffer on reproducibility of the migration time in capillary electrophoresis (CE) were investigated in the mode of capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC). The parameters include concentration, pH value, and the change of properties of the running buffer. The results showed that the reproducibility of migration times could be improved through three approaches. Firstly, the correlation between running buffer concentration and migration time was established, and the running buffer concentration was determined by conductivities to improve the reproducibility. Secondly, it was found that the residual running buffer on the capillary showed significant influence on the reproducibility of migration times. Thus, appropriate running or washing procedures between separations were necessary. Finally, the inlet reservoir buffer played an extremely important role in affecting the migration behaviors of solutes. By improving the test apparatus, reproducible migration time was achieved as a result of the increase in the frequency of replacement of the inlet reservoir buffer.