Enantioseparation of the antidepressant reboxetine.

The enantioseparation of reboxetine by HPLC was investigated using chiral stationary phases (CSPs) containing cellulose Tris(3,5-dimethylphenyl)carbamate on silica gel (Chiralcel OD column) as the chiral selector. Reversed phase HPLC was the technique of choice for the analytical enantioseparation of reboxetine, while the chiral semipreparative separation was obtained with the same CSP, but in normal phase conditions. The effects of the mobile phase pH and composition on analytical retention, enantioselectivity and resolution were investigated. The best performance was obtained using a mobile phase composed of 0.5M sodium perchlorate at pH 6 and acetonitrile in the 60/40 (v/v) ratio. The semipreparative separation has allowed obtaining pure enantiomers, but required the preparation of reboxetine free base. Different n-hexane/alcohol mixtures were tested as mobile phases, varying both the nature of the alcohol and its percentage in the mobile phase. Different n-hexane/alcohol mixtures were tested as mobile phase and the best results were obtained by using a mobile phase composed of n-hexane and 2-propanol (80:20, v/v).