A method has been developed to determine 18 kinds of amino acids by HPLC. Chromatographic conditions include using a Hypersil ODS - C18 column(100 mm×4.6 mm i. d. , 5μm), the mobile phase A is 0.05 mol/L sodium acetate buffer (pH = 6.5) containing 10 mL/L N, N-dimethylformamide and the mobile phase B is acetonitrile-water( volume ratio being 1:1) , the separation is performed with gradient elution, with 2,4-dinitro fluorobenzene( DNFB)-acetonitrile being used as the pre-column derivatization of the amino ac...