The ionic strength of a sample and the solvent used to dissolve it play a pivotal role in routine capillary electrophoresis (CE). The effects of these parameters can be very pronounced, ranging from improved separation and sensitivity to loss of resolution, shifting migration times, and even to equipment breakdown. CE practitioners should pay special attention to the sample-dissolving solvent and the ionic strength of the sample during method development, validation and routine operation.

Sample diluent ionic strength, pH, organic solvent composition and viscosity can all have a significant impact on the performance of CE separation. It is, therefore, essential that the choice of solvent is optimized during method development. The optimized diluent should be fully specified in the method and used consistently in method validation and all subsequent applications of the method.

The authors describe how this free downloadable software calculates and displays CZE separations after the user has entered sample and operations parameters. The underlying principles and mathematical basis are explained.

Guest author, Paul Cancalon, describes the role of capillary electrophoresis for the analysis of vitamins in citrus fruit juices. The separation is rapid with up to 30 citrus juice compounds capable of being separated in 20 min.

The authors provide an introductory description of MEEKC and highlight some of its applications. They demonstrate the separation possibilities offered by the technique for the analysis of pharmaceutical and non-pharmaceutical solutes.

This instalment explains why the use of internal standards improves the quantitative performance of CE...

The use of CE in three separate pharmaceutical companies is demonstrated as a successful technique for routine analysis...

The key features for method validation of small molecules using CE within the pharmaceutical industry are discussed...