阻抑速差催化光度法测定痕量色氨酸和酪氨酸

Determination of Trace Tryptophan and Tyrosine by Catalytic Spectrophotometry

研究了色氨酸、酪氨酸在硫酸环境中抑制碘对亚砷酸与硫酸铈氧化还原反应的催化作用及动力学条件。在 0 .0 0 1mol/LCe(SO4) 2 ,0 .0 0 1 2 5mol/LAs2 O3 ,0 .0 1 3mg/LKI ,0 .0 2 5 g/L和 0 .2 5 g/LNaCl溶液中测定色氨酸和酪氨酸 ,其线性范围分别为 0 .0～ 0 .6 5mg/L ,0 .0～ 4 .0mg/L和 0 .0～ 1 .3mg/L ,0 .1 0～ 4 .0mg/L ,用联立方程分别求出各自含量。用此法对醇溶蛋白质和混合氨基酸溶液中色氨酸和酪氨酸进行测定 ,混合氨基酸的色氨酸、酪氨酸测量值为 0 .80 37g/L ,3.5 91 g/L ;蛋白质的色氨酸、酪氨酸测量值为 1 .8g/kg、3.4 3g/kg ;回收率在 88%～ 1 0 9% ;色氨酸和酪氨酸的RSD分别为 4 .8%和 5 .2 % 。

The kinetic conditions for the inhibitory effect of tryptophan and tyrosine on the catalysis of iodide anion on the arsenous acid-cerium (IV) sulfate reaction in sulfuric acid medium were studied. The united equation was established for the determination of tryptophan and tyrosine in 0.001 mol/L Ce(SO4)(2), 0.00125 mol/L As2O3, 0.013 mg/L KI, 0.225 mol/L H2SO4, 0.025 g/L and 0.25 g/L NaCl solution the linear response range are 0.0similar to0.65 m g/L, 0.0similar to4.0 mg/L and 0.0similar to1.3 gm/L, 0.10similar to4.0 mg/L. The contents of two analytes were obtained respectively by solving the united equations. The method has been applied to determine tryptophan and tyrosine in protein and amino acid mixture with satisfactory results. The measured value of Trp and Tyr are 0.8037 g/L and 3.591 g/L in amino acid mixture are 1.8 g/kg and 3.43 g/kg in protein. The rate of recovery are 88%similar to109%. The relative standard deviation are 4.8% and 5.2% of tryptophan and tyrosine.