This patent discloses a method for resolution of 4-[4-(dimethylamino)-1-(4′-fluorophenyl)-1-hydroxybutyl]-3-(hydroxymethyl)-benzonitrile as a racemic or non-racemic enantiomer mixture into its isolated enantiomers, said method comprising the step of fractionally crystallizing 4-[4-(dimethylamino)-1-(4′-fluoro-phenyl)-1-hydroxybutyl]-3-(hydroxymethyl)-benzonitrile as a salt with the (+)—(S,S)— or (−)—(R,R)-enantiomer of O,O′-di-p-toluoyl-tartaric acid in a solvent system comprising 1-propanol, ethanol or acetonitrile.