Enantiomer separation of hydrophobic amino compounds by high-performance liquid chromatography using crown ether dynamically coated chiral stationaryphase

CROWNPAK CR(+) column, which is powerful for the separation of amino acid e nantiomers, must be used at a column temperature below 50 degrees C and a m obile phase containing less than 15% methanol, because the chiral crown eth er moiety of the stationary phase is dynamically coated on an ODS matrix. T he second peak of the enantiomers of alanine-beta-naphthylamide (Ala-beta-N A) appeared at 204 min (k(2) = 148) by using ordinary mobile phase, that is , a mixture of 10 mM perchloric acid and 15% methanol. In this study, enant iomer separations of Ala-beta-NA and 1-(1-naphthyl)ethylamine (1-NEA), both of which are hydrophobic amino compounds, were investigated through the mo dification of the mobile phase. Addition of crown ether, cyclodextrins (CDs ), cations, etc., affected the stability of the complex between an analyte and the chiral moiety, leading to fast separation. The second peak of the e nantiomers of Ala-beta-NA appeared at 68 min (k(2) = 49) through the additi on of 10 mM beta-CD, or at 61 min (k(2)=44) using potassium dihydrophosphat e as a buffer component. This method was applied for the optical purity tes ting of L-Ala-beta-NA, which is used as one of the chiral derivatization re agents for carboxylic compounds. Validations such as reproducibility and li nearity were also demonstrated and this method was found to be sufficient a s a quality control method for the optical purity testing of L-Ala-beta-NA. As little as 0.05% D-form in L-Ala-beta-NA could be determined. (C) 1999 E lsevier Science B.V. All rights reserved.