The Role Of Cyclodextrin Additives In Chiral Separation

In chromatographic separation, chiral substances are typically separated using chiral columns. However, there are other methods available for separation, such as the addition of chiral additives. Cyclodextrin is one commonly used chiral additive.

Cyclodextrin is a cyclic oligosaccharide composed of several glucose units linked together by a-(1,4) glycosidic bonds. Its molecular structure resembles a truncated cone, with numerous hydroxyl groups arranged along the rim and a relatively hydrophobic cavity in the interior. Cyclodextrins can form inclusion complexes with many molecules and exhibit strong selectivity in terms of molecular shape, size, and polarity, especially in the recognition of chiral molecules.

Application Example:
Separation of racemic hydrochloride of norepinephrine

Structural formula:

Chromatographic Column: Ultisil® XB-C8 (4.6×250mm, 5μm).
Mobile Phase: 10mM Sodium Dihydrogen Phosphate solution (containing 11.3g/L Sodium Sulfobutyl-β-Cyclodextrin, adjusted to pH 3.0 with phosphoric acid) / Methanol = 96/4.