ENANTIORESOLUTION OF DISOPYRAMIDE BY CAPILLARY AFFINITY ELECTROKINETIC CHROMATOGRAPHY WITH HUMAN ALPHA(1)-ACID GLYCOPROTEIN (AGP) AS CHIRALSELECTOR APPLYING A PARTIAL FILLING TECHNIQUE

A method using alpha(1)-acid glycoprotein (AGP) as chiral selector for disopyramide by means of affinity electrokinetic chromatography has b een developed. In order to avoid UV absorbance interferences, less tha n the effective length of the capillary was filled with the chiral sel ector. The electrophoretic conditions were chosen to give opposite mig ration directions for the chiral selector and the analyte; AGP migrate d away from the detector. Enantiomers of disopyramide were separated o n a methylcellulose-coated capillary with 20 cm length to the detector . The enantioresolution of the solute was affected by the concentratio n of the chiral selector, the plug length of the selector in the capil lary, and the applied voltage. Resolution factors and migration times decreased with reduction of the plug length, while the efficiency of t he separation system and peak performance were improved by decreasing the separation zone. A special feature of the technique is an enhanced selectivity due to increasing separation of the enantiomers when the fastest has migrated from the selector zone, while the second one stil l is retained. Equations relating selectivity and resolution with the difference in effective plug lengths between the two enantiomers are d eveloped. Optimized conditions yielding complete resolution, requiring an 0.75 mM AGP plug of only 4.5 cm effective length, also gave high e fficiencies (about 400 000 plates/m) for both enantiomer peaks.