Abstract: A reversed capillary electrophoresis with contactless high frequency conductivity detection method to determine amino acids mixture was described. In this study,cetyltrimethylammonium bromide（CTAB） was used to reverse electro-osmotic flow in order to shorten the analysis time. β-CD was added to optimize the separation further. The effects of separation potential,concentration of CTAB,buffer electrolyte and β-CD etc. were researched and the best analysis conditions were obtained. Ten kinds of amino acids were separated and detected directly in running medium of 15.0 mmol/L diethylamine/0.10 mmol/L H₃BO₃/0.10 mmol/L CTAB/0.25 mmol/L β-CD（pH=11.0） at the separation potential of -20 kV within 7 min. The correlation coefficients of amino acids are 0.991—0.999 in the linear range of 1.00×10^-6 —1.00×10^-3 mol/L,the limit of detection are 0.17—0.94 μmol/L（S/N=3）.

Key words: Reversed capillary electrophoresis, High frequency conductivity detection, Contactless conductivity detection, Amino acids