Amino acid analysis method

A method for analyzing amino acids by liquid chromatography, in which a sample containing a plurality of kinds of amino acids is derivatized with a derivatization reagent, and the obtained derivatized sample is passed on a column together with a mobile phase system,

• wherein the mobile phase system is composed of a plurality of mobile phases, and at least one mobile phase of the plurality of the mobile phases is a mixed solvent system,
• wherein two or more kinds of derivatized samples are prepared using two or more kinds of derivatization reagents,
• wherein different analytical conditions in which mixing ratio of the plurality of the mobile phases is changed with a passage of time are set for each kind of the derivatization reagent, and a solvent mixing ratio of solvents in the mixed solvent system is varied for the each kind of the derivatization reagent, and
• wherein the two or more kinds of derivatized samples are analyzed by automatically switching between the different analytical conditions and the solvent mixing ratios to separate and quantify derivatized L-amino acids and derivatized D-amino acids.