Application of retention factors in affinity electrokinetic chromatography and capillary electrophoresis.

Affinity capillary electrophoresis has become an established approach for performing interaction studies. In affinity electrokinetic chromatography the retention factor, as in liquid chromatography, is useful for describing the migration behavior of the analytes, and is instrumental for assessing the affinity of an analyte for the pseudo-stationary phase. Erroneous use of the retention factor concept in affinity capillary electrophoretic studies has appeared in a number of recent papers. The errors and their origin are pointed out, and the correct use of retention factors in affinity electrokinetic chromatography and capillary electrophoresis is summarized.