用多壁碳纳米管(MWCNTs)和亲水性离子液体N-乙基吡啶四氟硼酸盐([EtPy]BF4)作修饰剂,构置了修饰玻碳电极(MWCNTs-[EtPy]BF4/GCE),并应用电镜扫描法(SEM)和电化学阻抗法(EIS)对MWCNTs-[EtPy]BF4/GCE进行了表征。MWCNTs在[EtPy]BF。离子液体中能有效分散,增加了电极表面的活性位点,与裸GCE和MWCNTs-DMF/GCE相比,MWCNTs-[EtPy]BF4/GCE电导率最高。在pH6.8的PBS缓冲溶液中,用循环伏安法(CV)和差分脉冲伏安法(DPV)研究了10-羟基喜树碱在该修饰电极上的电化学行为,建立了一种测定10-羟基喜树碱注射液中10-羟基喜树碱含量的新方法。10-羟基喜树碱在MWCNTs-[EtPy]BF4/GCE上出现一对灵敏、可逆的氧化还原峰,峰电位差(△Ep)为40mV,与MWCNTs-DMF/GCE相比减小了80mV;10-羟基喜树碱在MWCNTs-[EtPy]BF4/GCE上的氧化、还原峰电流响应分别是在MWCNTs-DMF/GCE上的3.3倍和2.0倍,表明MWCNTs-[EtPy]BF4/GCE对10-羟基喜树碱的氧化还原反应有良好的电催化作用。在20—500mV/s扫速范围内,氧化还原峰电流均与扫速平方根(v^1/2)呈线性关系,表明该电极反应过程受扩散控制。在DPV曲线上,10-羟基喜树碱的氧化峰电流与其浓度在5.0×10^-6-1.8×10^-4g/L范围内呈良好的线性关系,检出限为1.0×10^-6g/L。方法用于10-羟基喜树碱药物的含量测定,RSD为2.9%~3.5%,加标回收率曲9R6%-105%。
A new modified glassy carbon electrode( MWCNTs-[Et Py]BF4/ GCE) was fabricated by using multiwall carbon nanotube and hydrophilic ionic liquid N-ethylpyridinium tetrafluoroborate as modifiers. The characteristic of MWCNTs-[Et Py]BF4/ GCE was characterized by scanning electron microscopy( SEM) technique and electrochemical impedance spectroscopy( EIS). The results showed that MWCNTs had an effective dispersibility in [Et Py]BF4ionic liquid,and increased the active site of the electrode surface; The conductivity was highest comparing to the bare GCE and MWCNTs-DMF/ GCE. The electrochemical behavior of 10-hydroxycamptothecin at the modified electrode was investigated in a PBS buffer solution( pH = 6. 8) by cyclic voltammetry( CV) and differential pulse voltammetry( DPV),and a novel method for the determination of 10-hydroxycamptothecin in 10-hydroxycamptothecin injection was thus established. A couple of sensitive and quasireversible redox peaks of 10-hydroxycamptothecin were observed on the MWCNTs-[Et Py]BF4/ GCE. At MWCNTs-[Et Py]BF4/ GCE,the peak-to-peak potential separation( ΔEp) of 10-hydroxycamptothecin was 40 m V; compared with MWCNTs-DMF/ GCE,the ΔEpdecreased by 40 m V. Furthermore,the oxidation and reduction peak current responses of 10-hydroxy-camptothecin at MWCNTs-[Et Py]BF4/ GCE were 3. 3 times and2. 0 times of these at MWCNTs-DMF/ GCE,respectively. These indicated the MWCNTs-[Et Py]BF4/ GCE possessed an excellent electrocatalytic activity for the redox of 10-hydroxycamptothecin. The redox peak currents were linear to scan rates in the range of 20 - 500 m V/ s,suggesting that the electrode process of 10-HCPT was controlled by diffusion. In the DPV curves,the oxidation peak current was linearly related to the concentration of10-hydroxycamptothecin in the range of 5. 0 × 10- 6- 1. 8 × 10- 4g/ L,with a detection limit of 1. 0 × 10- 6g/ L.The method was applied in the determination of 10-hydroxycamptothecin in samples. The relative standard deviation was between 2. 9% and 3.