Abstract: Four important amino acids, arginine (Arg), tryptophane (Trp), phenylalanine (Phe) and tyrosine (Tyr) in tea samples with different fermentation processes were simultaneously determined by capillary zone electrophoresis (CZE) using direct ultraviolet detection (UV) at 190 nm. Under the conditions of 20 kV of separation voltage and 25 ℃ of temperature, Arg, Trp, Phe and Tyr were separated successfully within 8 min in 25 mmol/L sodium borate-boric acid (pH 10.0) with the detection limits of 5.0, 1.0, 0.3 and 0.5 mg/L for Arg, Trp, Phe and Tyr, respectively. The relative standard deviations (RSDs) of migration time (n=7) were all lower than 2.8% and the RSDs of peak electric current (n=7) were lower than 4.0%. The method was applied in the determination of Arg, Trp, Phe and Tyr in eleven tea samples. The results were satisfactory. This method can provide beneficial reference to evaluation quality of tea.

Key words: amino acid, capillary zone electrophoresis (CZE), direct ultraviolet detection, tea , underivatization