PURPOSE: To make quick analysis while maintaining high sepn. performance by using silica which is chemically bonded with an octadecyl group as a stationary phase and a buffer soln. of 2W4 pH which contains sodium octanesulfonate and acetonitrile or methanol as a moving phase.
CONSTITUTION: A cell 2 of the moving phase soln. prepd. by mixing 10W30% acetonitrile or 20W50% methanol with the phosphoric acid buffer soln. of 2W4 pH prepd. by dissolving the sodium octanesulfonate which acts as an ion pair reagent is connected via a pump 3 to the inflow end side of a column 1 for reversed phase chromatography contg. silica particles chemically bonded with the octadecyl group on the surface as a packing material. A sample contg. arom. amino acid is analyzed by such apparatus and the separated component is detected by a derivative formation method, etc. The arom. amino acid is analyzed in a short period by the above-mentioned method while high separability is maintained.