In contrast to capillary zone electrophoresis, micellar electrokinetic capillary chromatography can be applied to the determination of compounds that are unchanged and almost insoluble in water. As a screening parameter, the pseudo-effective mobility is to be preferred to the capacity factor k' because it can be calculated if tMC is unknown, and because it gives a better indication of whether components can be separated or not. Special attention should be paid, however, to the composition of the sample solution. The use of organic solvents to dissolve the sample can influence the separation enormously. Calibration graphs were constructed for some drugs and as an example dapsone in tablets was determined.