Chiral Capillary GC Columns

Cyclodextrin-based DEX and Astec CHIRALDEX phases are stable, high boiling liquids and make effective CSPs for enantiomer separations by GC. The two lines exhibit complementary selectivity.

Cyclodextrins are macromolecules composed of 6 or more D(+)-glucose residues bonded through α-glycosidic linkages. They are classified according to the number of glucose residues they contain: α-cyclodextrins (six residues), β-cyclodextrins (seven residues), and γ-cyclodextrins (eight residues). The three different sizes separate analytes over a wide range of molecular size. All hydroxyl groups, whether at the 2, 3 or 6 position, can be selectively modified with a derivative to impart unique physical properties and inclusion selectivities. Unlike LC, without derivatization no enantiomeric selectivity is exhibited in GC.

Selectivity is a function of the derivative, the degree of derivatization, the position of the derivative on the cyclodextrin, whether the derivatized cyclodextrin is used neat or doped into a polysiloxane, and if doped, at what percentage. Certain CSPs are more selective for given molecular structures and often more than one will achieve a separation. CSPs may be chosen to optimize resolution, but also elution order or analysis time. It is conventional practice to screen multiple CSPs when developing a new method. To help our customers, we offer column screening kits and a column screening service for this purpose.