Dansyl and dabsyl amino acids were separated by reverse-phase high-performance liquid chromatography on a short column (4.6×50mm) packed with 3μm ODS particles using a gradient formed from acetone and 10 mM sodium phosphate buffer, pH 6.5 or 7. 0. The light absorption of the derivatives was used for the detection giving a sensitivity of less than 50 pmol for a dansyl derivative or 10 pmol for a dabsyl derivative. This system was applicable to the amino acid analyses, amino-terminal analyses, and carboxyl-terminal analyses with less than 1 nmol of peptides.