Separation of ketoconazole enantiomers by chiral subcritical-fluid chromatography.

The separation of ketoconazole enantiomers by subcritical-fluid chromatography using an amylose-based column is described. Drastic changes in the resolution have been obtained for the different organic modifiers evaluated, with ethanol providing the best results. Other chromatographic parameters such as temperature, pressure and flow-rate have also been studied. The best results in terms of resolution and analysis time were obtained using 30% ethanol (containing 0.1% triethylamine and 0.1% trifluoroacetic acid), a pressure of 300 bar, a temperature of 35 degrees C and a flow-rate of 3 ml/min. Under these conditions the ketoconazole enantiomers are resolved in a short time (less than 7 min) and with high resolution (4.29).