线扫伏安法同时测定5-羟基色氨酸和色氨酸

Linear Scanning Voltammetry for the Simultaneous Determination of 5-Hydroxytryptophan and Tryptophan

研究了色氨酸和5-羟基色氨酸在玻璃碳电极上的电化学行为,研究了不同pH、静置时间、扫描速度以及表面活性剂等的影响,探讨了色氨酸和5-羟基色氨酸在玻璃碳电极上的氧化机理,建立了线扫伏安法同时测定色氨酸和5-羟基色氨酸的方法。实验发现,在含3.33×10-4mol/L十二烷基磺酸钠的0.1mol/L柠檬酸(pH=4.50)介质中,5-羟基色氨酸和色氨酸分别在+0.675V和+1.070V产生一灵敏的氧化峰。对5-羟基色氨酸,相应的氧化峰的峰高与浓度在2.40×10-5mol/L～8.00×10-4mol/L范围内呈良好的线性关系,线性相关系数为0.9994;对色氨酸,其氧化峰的峰高与浓度在2.40×10-5mol/L～6.40×10-4mol/L浓度范围内呈良好的线性关系,线性相关系数为0.9929。该方法测量2.00×10-4mol/L色氨酸和5-羟基色氨酸的相对标准偏差分别为3.2%和3.8%(n=10)。

Electrochemical behaviour of 5-hydroxytryptophan and tryptophan on the glassy carbon electrode was studied through investigation of the effect of the pH, scanning rate, surfactants etc. A novel linear scanning vohammetry for the simultaneous determination of the 5-hydroxytryptophan and tryptophan in the mixture was established. In 0. 1mol/L citric acid containing 3.33 × 10^-4mol/L SDS（pH 4.50）, 5-hydroxytryptophan and tryptophan can be oxidized on the electrode to produce an oxidized current at the potential of ＋ 0.675V and ＋ 1.070V（vs Ag/AgCl） respectively. The corresponding peak current of 5-hydroxytryptophan is proportional to the concentration of the 5-hydroxytryptophan within 2.40 × 10^-5 - 6.40× 10^-4mol/L, for tryptophan, the linear range is 2.40 × 10^-5 - 8.00 × 10^-4 mol/L, the linear correlation coefficients are 0.9929 and 0.9944 respectively. The RSD is 3.1% and 3.8% （ n = 10） for 2.00 × 10^-4mol/L 5-hydroxytryptopha and tryptophan respectively.