Development of a thin-layer chromatographic method for the enantioresolution of sotalol using levofloxacin as chiral selector

In this work, a commercially available, chirally pure pharmaceutical containing carboxylic group, namely, levofloxacin was utilized as chiral selector for the enantioresolution of sotalol. The TLC plates were prepared by mixing levofloxacin in silica gel slurry. The racemic mixture of sotalol was applied on TLC plates using MeCN–MeOH–HO (5.2:2.0:0.8, V/V; pH = 5.0) as the mobile phase at 22 (± 2) °C. The separation conditions were optimized in terms of concentration of chiral selector, pH, and temperature to get successful separation. The resolution value was observed to be 2.6. The enantiomers so separated were isolated from TLC plates and characterized using various techniques. The method found to be linear with calibration equation [y = 0.79x + 0.054] and a regression coefficient (r) value of 0.996. The limits of detection and quantification for the enantiomers were 2.3 μg/spot and 6.7 μg/spot, respectively. The recovery of the enantiomers isolated from TLC plates was in the range of 76–85%.