异烟肼在多壁碳纳米管修饰电极上的电化学行为及电化学测定

Electrochemical Behavior and Determination of Isoniazid at Multi-wall Carbon Nanotube Modified Electrode

报道了一种测定异烟肼的化学修饰电极和电分析方法.与裸玻碳电极相比, 多壁碳纳米管修饰玻碳电极显著提高异烟肼的氧化峰电流.优化了底液、pH值、修饰剂量、富集电位和富集时间等测定条件,建立了一种直接测定异烟肼的高灵敏度电分析方法.该方法测定异烟肼的线性范围为4×10-7～5×10-5 mol/L;富集60 s后的检出限为1.5×10-7 mol/L;对5×10-6 mol/L的异烟肼平行测定10次的相对标准偏差为4.9%.此方法成功用于异烟肼片剂和血清中异烟肼含量的测定.

A novel chemically-modified electrode and electrochemical method for the determination of isoniazid were reported. Compared with the bare glassy carbon electrode （GCE）, multi-wall carbon nanotube （MWNT）-modified GCE can greatly enhance the oxidation peak current of isoniazid. The electrochemical behaviors of isoniazid in various medium such as pH 5.0 - 8.0 phosphate buffer, pH 3.5 - 5.6 NaAc-HAc buffer, pH 8.0 - 11.0 NH3-NH4Cl buffer, pH 1.8 - 12.0 Britton-Robinson buffer （each 0.1 mol/L） , were compared. It is found that the oxidation response of isoniazid is best in pH = 5.0 B-R buffer since the peak current is highest and the peak shape is best-defined. The influence of the amount of MWNT-DHP suspension on the oxidation peak current of isoniazid was also examined. The oxidation peak current increases significantly by increasing the MWNT-DHP suspension from 0 to 6μL, and then increases slighty from 6 to 10 μL and finally decreases. Thus, the amount of 1 g/L MWNT-DHP suspension is chosen as 8μL in this work. Additionally, the effect of scan rate on the oxidation peak current of isonizid was tested by linear sweep voltammograms （LSV）. The oxidation peak current, in the range of 0. 025 -0.3 V/s, had a good linear relationship with scan rate, indicating that the oxidation of isoniazid at the MWNT-modified GCE is an adsorption-controlled process. The oxidation peak current increases greatly within the first 60 s and then levels off. Therefore, 60 s accumulation was used to improve sensitivity and shorten sample analysis. After that, a sensitive and rapid electrochemical method was developed for the determination of isoniazid. The oxidation peak current changes linearly with the concentration of isoniazid over the range from 4 × 10^-7 to 5 × 10^-5 mol/L. The detection limit is about 1.5×10^-7 mol/L for 60 s accumulation. The relative standard deviation was 4.9% for 5 × 10^-6 mol/L isoniazid （n = 10）. Finally, this method was successfully employed to determine isoniazid in isoniazid tablets and blood serum.