Ligand exchange thin layer chromatographic enantioresolution of (RS)-ketorolac and (RS)-etodolac and recovery of native enantiomers

Abstract

Direct resolution of (RS)-ketorolac and (RS)-etodolac has been achieved by ligand exchange thin layer chromatography. Cu(II) has been used as a complexing ion with three enantiomerically pure amino acids (namely, l-tryptophan, l-histidine and l-phenylalanine) as chiral dopants. Chromatograms were developed using different combinations of solvent systems in different ratio having no chiral additive. Iodine vapors were used for location of spots. Different experimental factors, i.e., effect of temperature, mole ratio of Cu(II) to l-amino acids and solvent ratio were optimized in order to improve the separation efficiency. Results have been compared (for RF and Rs). Limit of detection for each enantiomer of both the racemic analytes (ketorolac and etodolac) was found to be 0.6 and 0.8μg.