Validated chiral liquid chromatographic method for the enantiomeric separation of Pramipexole dihydrochloride monohydrate

A chiral liquid chromatographic method was developed for the enantiomeric resolution of Pramipexole dihydrochloride monohydrate, ( S)-2-amino-4,5,6,7-tetra-hydro-6-(propylamino) benzothiazole dihydrochloride monohydrate, a dopamine agonist in bulk drugs. The enantiomers of Pramipexole dihydrochloride monohydrate were resolved on a Chiralpak AD (250 mm × 4.6 mm, 10 μm) column using a mobile phase system containing n-hexane:ethanol:diethylamine (70:30:0.1, v/v/v). The resolution between the enantiomers was found not less than eight. The presence of diethylamine in the mobile phase has played an important role in enhancing chromatographic efficiency and resolution between the enantiomers. The developed method was extensively validated and proved to be robust. The limit of detection and limit of quantification of ( R)-enantiomer were found to be 300 and 900 ng/ml, respectively for 20 μl injection volume. The percentage recovery of ( R)-enantiomer was ranged from 97.3 to 102.0 in bulk drug samples of Pramipexole dihydrochloride monohydrate. Pramipexole dihydrochloride monohydrate sample solution and mobile phase were found to be stable for at least 48 h. The proposed method was found to be suitable and accurate for the quantitative determination of ( R)-enantiomer in bulk drugs.