碳糊电极测定氨基酸的研究——Ⅲ.组氨酸的测定

Determination of Ammo-acid With Carbon Paste Electrode——Ⅲ. Determination of Histidine

本文报道碳糊电极在含有组氨酸的HAc-NaAc(pH=4.l)溶液中,于-0.10V电位下富集,发现在-0.45V有一灵敏的还原峰.用循环伏安法对它的电化学性质进行了研究,发现在阳极支没有氧化峰,这是一不可逆电极过程.但可用于组氨酸的测定.用微分脉冲伏安法测定组氨酸的最佳测试条件为:pH=4.l的HAc-NaAc,液体石蜡含量为30%,富集电位0.10V,富集时间60s.在4.0~20μg/mL范围内有良好的线性,其标准偏差为0.21,检出限为1.0μg/mL.其余19种氨基酸不干扰组氨酸的测定,可直接用于氨基酸药物样品的分析.并对组氨酸在碳糊电极表面的反应机理进行了讨论.

The electrochemical property of histidine was investigated by cyclic voltammetry at carbon paste electrode. Histidine at the electrode was accumulated in HAc-NaAc(pH = 4. 1) solution at -0. 10 V (vs. Ag/AgCl) for bos, and then it was determined by differential pulse voltammetry. The reduction peak of histidine was observed at -0. 45 V. The relationship between the peak current and histidine concentration was linear in the range of 4. 0-20. 0 μg/mL, and a detection limit of 1. 0 μg/mL for histidine was obtained. The relative standard deviation was 6. 3%. The method has been applied to the determination of histidine in amino-acid compound injection with satisfactory results. The electrochemical reaction mechanism on this electrode for histidine is studied by cyclic voltammetry.