Separation of Dansyl-DL-Amino Acids Through Tube Radial Distribution Chromatography by Using a Commercially Available HPLC System with a Capillary Tube Manufactured for GC as a Separation Column

Dansyl- DL -amino acids were separated by tube radial distribution chromatography (TRDC) comprising a commercially available HPLC system, where open-tubular capillary tubes manufactured for capillary GC were used as the separation column. Initially, the separation performance of GC capillary tubes in TRDC was assessed by separating a model analyte mix of 1-naphthol and 2,6-naphthalenedisulfonic acid by using water/acetonitrile/ethyl acetate solutions (3:8:4 volume ratio, organic solvent-rich and 4:3:1 volume ratio, water-rich) as the eluent and high-polarity and non-polarity capillary tubes. Next, enantiomer separation of dansyl- DL -methionine and dansyl- DL -valine was examined using a water/acetonitrile/ethyl acetate solution (8:2:1 volume ratio, water-rich) containing 1.0 mM  -cyclodextrin and non-polarity capillary tubing. The D - and L -enantiomers were separated and detected in this order through interaction between amino acids and  -cyclodextrin by tube radial distribution flow in the TRDC system.