溴取代紫外分光光度法同时测定痕量色氨酸和酪氨酸

Simultaneous Determination of Trace Tryptophan and Tyrosine by Ultraviolet Spectrophotometry with Substituted Bromination

研究了在水和乙醇溶液中Br2与色氨酸和酪氨酸发生的取代反应,利用测定反应前后Br2与KI反应生成I2的量,建立了不经分离同时测定色氨酸、酪氨酸的新方法。用I2在水和乙醇水溶液中对紫外光的吸收不同和加和原理,建立联立方程并分别求得各自的含量。方法测定色氨酸和酪氨酸的线性范围分别为0.0～0.90mg·L-1和0.0～1.00mg·L-1,表观摩尔吸光系数(ε)在水溶液中分别为1.65×105、1.71×105 L.mol-1.cm-1;在乙醇水溶液中分别为2.31×105、2.05×105 L.mol-1.cm-1。用该法对复合氨基酸溶液和鸡蛋清中色氨酸和酪氨酸进行测定,相对标准偏差分别为1.8%、1.2%,回收率为96.0%～104.3%。

The reaction of bromine with tryptophan（Trp）and Tyrosine（Tyr）in water solution or ethanol solution were studied.Based on the absorbance difference of I2in water and ethanol solution,a method for simultaneous determination of the content of Try and Tyr was developed.The linear ranges of Try and Tyr were abtained in 0.0-0.90mg.L-1 and 0.0-1.00mg.L-1.The apparent molar absorption coefficient of Trp and Tyr are 1.65×105,1.71×105 L.mol-1.cm-1 in aqueous solution and 2.31×105,2.05×105 L.mol-1.cm-1 in ethanol.The method has been applied to determine Tryp and Tyr in mix amino acid and egg white with satisfactory results.The relative standard deviations are 1.8%and 1.2%,and the recovery was found to be 96.0%-104.3%.