Influence of operating parameters on reproducibility in capillary electrophoresis.

The reproducibility of two migration parameters (retention time and mobility) of a seven-component test mixture was examined under various operating conditions using laboratory-built capillary electrophoresis systems. It was found that the frequency of rinsing the capillary and the solutions used for rinsing had the greatest effect on migration reproducibility. In addition, it was found that the migration behavior of solutes that interact with micelles is not repeatable unless the proper rinse protocol is applied. Inconsistent migration behavior is linked to inconsistent total current of the system. Preliminary investigations indicate that the fluctuation in total current were associated with non-equilibrium conditions between the buffer and the capillary wall.