Fig.1
The chiral purity of D-phenylalanine was analyzed by HPLC. HPLC analysis with standard solution of L-phenylalanine and D-phenylalanine showed that the peak time of L-phenylalanine was about 25 min, and the peak time of D-phenylalanine was in 33 min (Fig.S1). HPLC detection condition for D/L phenylalanine was as follow: Chromatographic column: Philomon Chirex 3126 (D)-Penicillamine 250 nm×4.6 nm, 5 μm; mobile phase: 5% (v/v) acetonitrile and 95% (v/v) 2.0 mM, CuSO4 aqueous solution; flow rate: 0.8 mL/min; detection wavelength: 254 nm.