Abstract: AIM: To establish a reversed-phase high performance liquid chromatographic method for simultaneous determination of 10 amino acids in serum.METHODS: The sample was mixed with norleucine as the internal standard,then derivatized with phenylisothiocyanate(PITC)and analyzed on a Venusil-AA column at 40 ℃,using gradient elution with detection at 254 nm.RESULTS: The correlation coefficients between the ratios of peak area of amino acid to that of the internal standard and the amino acid concentrations were all above 0.99 in the linear range 15.6-250 μmol/L.The recoveries of amino acids added were 96.3％-103.4％,with-in and between day precision were less than 4.8%.The method was applied to analyze free amino acids in infants plasma and good results were obtained.CONCLUSION: The method is simple, stable, the separation of amino acids is satisfactory.It can be used for determination of amino acids in human plasma.

Key words: HPLC, Precolumn derivatization, Phenylisothiocyanate, Norleucine, Amino acid