固体石蜡作粘合剂的纯碳糊电极的电化学活化及其应用于色氨酸的测定

Electrochemical Activation of a Carbon-Paste Electrode With Paraffin as a Binder and Its Application to the Determination of Tryptophan

研究了以固体石蜡作粘合剂的纯碳糊电极的电化学活化及用于色氨酸直接测定的方法。活化后的电极对色氨酸的吸附能力大大增加，在ＨＡｃ－ＮａＡｃ（ｐＨ＝３．５）溶液中，于＋０．３ Ｖ富集后，于＋１．０１出峰，用线扫伏安法测定时，二次微分溶出峰电流ｅ”ｐ与色氨酸浓度在 ８～１００ μｇ／Ｌ范围内成线性；检测限可达 ２ μｇ／Ｌ；２倍的酪氨酸和其它氨基酸不干扰，用于氨基酸药物样品和合成血清样品中色氨酸的测定，相对标准偏差小于２％。

The pre-electrochemical activation of a carbon-paste electrode (paraffin/graphite) and the determination of tryptophan at the activated electrode have been studied. The carbon paste electrode was pre-oxidized in HAc-NaAc(pH 3. 5) buffer solution at +1. 8 V Ag/AgCl electrode for 10 min under stirring. The adsorption of tryptophan was greatly enhanced on the activated electrode. Tryptophan was accummulated in the HAc-NaAc solution at poten- tial of +0. 3 V for a certain time, and then was determined by differential anodic stripping voltammetry. An oxidative peak was observed at +1. 01 V(scan rate 490 mV/s). The rela- tionship between peak current and tryptophan concentration is linear in the range of 8-100 μg/L tryptophan and the detection limit is 2 μg/L. The method has been applied to the de- termination of tryptophan in amino acid compound injection and spiked serum samples. The relative standard deviation (6 times) is less than 2%.