Principle and applications of the partial filling technique in capillary electrophoresis

The partial filling technique (PFT) in capillary electrophoresis (CE) is an efficient system where, only 50-800 nanolitres of a chiral selector soluti on needs to be added to each run. PFT is especially applicable when these a dditives to the background electrolyte (BGE) are expensive or absorb UV lig ht. The selector dissolved in the BGE is applied to the capillary as a plug , shorter than the effective length of the capillary, prior to application of the analyte. During the run both ends of the capillary are connected to the BGE. The applied plug and the analyte may move in opposite directions o r in the same direction at different velocities depending on their electrop horetic mobilities. Thus the final plug length is either longer or shorter than the original length. The technique has been successfully applied in a number of studies including enantiomeric separation with a variety of selec tors, and for the determination of conditional association constants.