LC-separation of derivatized DL-amino acids by aminopropylsilica-bonded Marfey's reagent and analog

Two chiral stationary phases (CSP-1 and CSP-2) were synthesized by covalent bonding of aminopropylsilica (APS) to (a) 1-fluoro-2,4-dinitrophenyl-5-L-alanine amide (Marfey's reagent), followed by end-capping of underivatized amino groups of APS with trifluoroacetic anhydride (CSP-1), and (b) by reaction of APS with 1-fluoro-2 4-dinitrophenyl-5-L-phenylalanine tert. butyl ester, followed by cleavage of the tert. butyl ester by trifluoroacetic acid and end-capping of underivatized amino groups of APS with n-butyryl chloride (CSP-2). Both CSPs were found to be suitable for the chiral resolution of 2,4-dinitrophenyl and 3,5-dinitrobenzoyl-DL-amino acid esters by liquid chromatography using mixtures of n-hexane and iso-propanol as eluents. Racemic 2,2,2-trifluoro-1-(9-anthryl)ethanol was also resolved on CSP-2.