非衍生化毛细管区带电泳直接紫外检测法测定茶叶中的4种氨基酸

采用非衍生化毛细管区带电泳直接紫外检测法同时分离测定精氨酸(Arg)、色氨酸(Trp)、苯丙氨酸(Phe)和酪氨酸(Tyr)4种氨基酸,并应用于不同发酵过程的茶叶样品的测定。在分离电压为20 kV、柱温为25 ℃、检测波长为190 nm条件下,以25 mmol/L硼酸-硼砂缓冲溶液(pH 10.0)为运行缓冲液,4种组分在8 min内达到基线分离,Arg、Trp、Phe、Tyr的检出限分别为5.0,1.0,0.3和0.5 mg/L。7次平行测定中,4种组分迁移时间的相对标准偏差(RSD)均小于2.8%,峰电流的RSD均小于4.0%。将所建立的方法用于11种实际茶叶样品中Arg、Trp、Phe和Tyr含量的测定,结果令人满意。该方法可以为茶叶的质量评估提供借鉴。

Determination of four amino acids in tea by capillary zone electrophoresis and direct ultraviolet detection without derivatization

Four important amino acids, arginine ( Arg) , tryptophane (Trp) , phenylalanine ( Phe) and tyrosine (Tyr) in tea samples with different fermentation processes were simultane-ously 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 re-sults were satisfactory. This method can provide beneficial reference to evaluation quality of tea.