Astec CLC phases are based on coupling an enantiomeric form of an amine to a proprietary derivative to create an appropriate distance for copper coupling. In theory, any analyte that can complete the coordination with the copper ion can be resolved (e.g., lactic, malic, tartaric and mandelic acids). CLC HPLC columns are either CLC-D or CLC-L, depending on the enatiomeric form of the coupled amine. For the CLC-D column, L enantionmers generally elute before D, except for tartaric acid. For the CLC-L column, D enantiomers generally elute before L.

Competive columns are available only in the D-form. We offer both L and D forms allowing for reversal of elution order. This is important for trace analysis (purity test) where the minor peak should elute first. L-lactic acid will elute as second peak using CLC-L while D-lactic acid will elute as second peak using CLC-D and competitive columns. Of the two isomers, L-lactic acid is the biologically important enantiomer. Most commonly, users have the L-form isomer so the use of Astec CLC-L for purity test is the best choice.