Chiral Capillary GC Columns

Astec CHIRALDEX

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Frequently Asked Questions - over 60 topics to assist you with chiral chromatography!

 


Chiral GC Columns Brochure
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Astec CHIRALDEX capillary GC columns incorporate phases consisting of derivatives of α-, β-, or γ-cyclodextrin for the separation of enantiomers. These columns can routinely separate a variety of underivatized non-aromatic enantiomers and several aromatic enantiomers that remain difficult to resolve by HPLC. These columns specifically and effectively separate many of these types of molecules including thousands of compounds that are starting materials or intermediates for chiral synthesis, biochemical and pharmaceutical intermediates and metabolites, environmental contaminants, flavors, etc. The resolution of small chiral compounds has been a major growth factor for capillary GC. With their high degree of inertness and low bleed, Astec CHIRALDEX columns are ideal for these types of separations.

 

Stationary Phases and Maximum Allowable Operating Temperatures

Eight derivative types are available, ranging from simple dimethyl to complex trifluoroacetyl, and are referred to using a two-letter code for simplification. The fact that there are three different size cyclodextrins (α-, β-, or γ-) allows for separation of a wide variety of different size analytes.

A total of fifteen unique chiral stationary phases (CSPs) are available. Selectivity of these phases is a function of the derivative, the degree of derivatization, and the position of the derivative on the cyclodextrin. Because these cyclodextrin derivatives are stable, high boiling liquids, they make effective stationary phases for gas-liquid chromatography.

All Astec CHIRALDEX columns are temperature rated which may be a limiting factor in the choice of the column. The maximum allowable operating temperature (MAOT) both for isothermal and temperature programmed conditions is given below. These temperatures are not recommended for extended periods.


Astec CHIRALDEX column kits provide method developers with three columns, each containing a unique phase, that cover the widest possible range of enantioselectivity.


Type / Name Derivative α-Phase β-Phase γ-Phase Max. Temp. (°C)
Isothermal
Max. Temp. (°C)
Programmed
TA / Trifluoroacetyl 2,6-di-O-pentyl-3-trifluoroacetyl A-TA B-TA G-TA 180 180
DP / Dipropionyl 2,3-di-O-propionyl-6-t-butyl silyl   B-DP G-DP 200 220
PN / Propionyl 2,6-di-O-pentyl-3-propionyl     G-PN 200 220
BP / Butyryl 2,6-di-O-pentyl-3-butyryl     G-BP 200 220
DM / Dimethyl 2,3-di-O-methyl-6-t-butyl silyl   B-DM G-DM 200 220
PM / Permethyl 2,3,6-tri-O-methyl   B-PM   200
220
DA / Dialkyl 2,6-di-O-pentyl-3-methoxy A-DA B-DA G-DA 200 220
PH / Hydroxypropyl (S)-2-hydroxy propyl methyl ether   B-PH   200 220


Choosing the right column for a given enantiomeric separation is dependent on many factors, including analyte structure (aliphatic vs. aromatic, functional groups, etc.) and elution temperature. While many compounds can be enantiomerically resolved on multiple Astec CHIRALDEX phases, often an advantage can be found in selectivity, elution order, and/or analysis speed from one phase to another.