Enantiomer Separation of N-Protected α -Amino Acids on Covalently Immobilized Cellulose Tris(3,5-chlorophenylcarbamate) Chiral Stationary Phase in HPLC

Abstract

11.03) except for N-PHT 2-aminocaprylic acid and sixteen N-FMOC α-amino acids (α = 1.20-1.73, Rs = 1.75-7.19) except for N-FMOC glutamic acid and glutamine were baseline resolved. The elution orders of these analytes are shown in Table 1 and Table 2. The L-enantiomers of all N-PHT αamino acids were preferentially retained except for N-PHT phenylglycine (Table 1, entry 11), while the D-enantiomers of the examined N-FMOC α-amino acids were preferentially retained. The chromatographic method in this study was applied for determination of the enantiomeric purity of three commercially available analytes (N-PHT L-glutamic acid, N-PHT Lphenylalanine and N-FMOC L-phenylglycine) as well as other synthesized N-protected α-amino acids on Chiralpak IC. The enantiomeric impurities of 0.42, 0.38 and 0.50% for these three commercially available analytes were determined, respectively. Also the degree of racemization for other synthesized N-protected PHT and FMOC α-amino acids was determined, as shown in Tables 1 and 2. The degree of racemization of N-protected FMOC α-amino acids prepared in this study was pretty lower (< 0.77%) than that of Nprotected PHT α-amino acids. 16 Since the enantiomeric purities of nine N-FMOC α-amino acids analytes were not detected in Table 2, it was concluded that the racemization of nine analytes among the examined seventeen N-FMOC α-amino acids analytes did not occur during FMOC protecting procedure of amino group. In the case of N-protected