FIG. 5.

Chiral resolution of dl-phenylalanine. Direct enantiomeric resolution of d-phenylalanine from dl-phenylalaninamide was achieved by HPLC (A) and TLC (B). (A) Determination of the dl-amino acids by HPLC was monitored with a fluorescence detector (excitation at 342 nm and emission at 452 nm). The reactant was resolve with a 50 mM sodium acetate (pH 6.8)-methanol linear gradient system after derivatization with OPA. (B) dl-Isomers were developed with methanol-H₂O-acetonitrile (5:5:20 [vol/vol/vol]). The amino acid spots were detected with ninhydrin (0.2% in ethanol). Reactant samples were withdrawn at various times. Lanes 1 and 2, authentic dl-Phe and d-Phe, respectively; lane 3, after 0 min; lane 4, after 5 min; lane 5, after 3 h; lane 6, after 6 h; lane 7, after 9 h; lane 8, after 12 h; lane 9, after 24 h.