Determination of 18 kinds of amino acids in multi-amino-acid tablets by RP-HPLC method and amino acid analyzer

Objective: To compare the methods of RP-HPLC and amino acid analyzer(AAA) for determining concentrations of amino acids.Methods: Eighteen kinds of amino acids in multi-amino-acid tablets were measured by an Agilent HPLC and Hitachi 835-50 amino acid analyzer.One C_(18) column was used for HPLC method with o-pathalaldehyde precolumn derivation.An ion exchange chromatography column was used for AAA method with ninhydrin postcolumn derivation.Results: The coefficients of variation of HPLC and AAA methods were less than 1.5% and 3.0%,respectively.The minimal detectable(limit) was 3 pmol for HPLC method and 30 pmol for AAA method.The results obtained from RP-HPLC were correlated to those of AAA method.The average relative standard deviation of the two methods was 5.74%(ranged from 0.24% to 9.60%).Conclusion: Both methods can be used to determine the concentrations of amino acids,but there is difference between the results of the two methods.