REVERSED-PHASE THIN-LAYER CHROMATOGRAPHIC SEPARATIONS OF ENANTIOMERS OF DANSYL-AMINO ACIDS USING BETA-CYCLODEXTRIN AS A MOBILE-PHASE ADDITIVE

The DL-racemates of nine proteinogenic amino acids were resolved by reversed-phase thin-layer chromatography after conversion to their 5-dimethylamino-1-naphthalene sulfonyl (dansyl) derivatives. The chiral selector beta-cyclodextrin was used in the mobile phase along with either aqueous acetonitrile or aqueous methanol as an organic modifier. DL-Histidine was separated as both its mono- and didansyl derivatives. It was determined that it was the cyclic nature of two imino acids DL-proline and DL-pipecolic acid that prevented their enantiomeric separations under the conditions employed. The DL-racemates of four non-proteinogenic amino acids, two of which are involved in the urea cycle, were also separated.