洛哌丁胺在碳纳米管碳糊电极上的伏安行为及其测定

Voltammetric Behavior of Loperamide and Its Determination at Multi-wall Carbon Nanotube Paste Electrode

用循环伏安法和控制电位库仑法研究了洛哌丁胺在多壁碳纳米管碳糊电极(MCNT-PE)上的伏安行为及反应机理。在pH7.2伯瑞坦-罗宾森(B-R)缓冲液中,洛哌丁胺于+0.89V(vs.SCE)处产生一氧化峰。其电极反应是由吸附控制的不可逆2电子2质子过程。与碳糊电极(CPE)相比,洛哌丁胺在MCNT-PE上的峰电位较低,峰电流较高。基于洛哌丁胺的阳极伏安行为,建立了差分脉冲伏安法测定其含量的方法。线性范围为4.0×10-7～2.0×10-5mol/L,检出限为7.8×10-8mol/L。该法用于测定胶囊中洛哌丁胺的含量,结果满意。

The vohammetric behavior and oxidation mechanism of loperamide were investigated by cy- clic voltammetry and coulometry at a multi-wall carbon nanotube paste electrode （ MCNT - PE）. In pH 7.2 B - R buffer, loperamide yielded an oxidation peak at ＋ 0.89 V （vs SCE）. The oxidation of loperamide was an adsorption-controlled irreversible two-electron and two-proton process. The oxida- tion peak potential of loperamide at MCNT -PE was lower than that at carbon paste electrode（ CPE）, while the peak current at MCNT -PE was higher than that at CPE. Based on its anodic vohammetric behavior, a differential pulse vohammetry （DPV） was proposed for the determination of loperamide at MCNT - PE. The increase of the oxidation peak current was linear with the concentration of loperamide from 4.0 ×10^-7 to 2.0 ×10^-5 mol/L with a detection limit of 7.8 ×10^-5 mol/L. The spiked recoveries were in the range of 94% - 105% with RSDs of less than 3.1% . The proposed method had good repeatability and sensitivity, and was successfully applied in the determination of loperamide in capsules.