对乙酰氨基酚在多壁碳纳米管L-半胱氨酸共组装修饰金电极上的电化学行为研究及其测定

Electrochemical Behaviors and Determination of Paracetamol at Multi-walled Carbon Nanotubes and L-Cysteine Co-Assembling Modified Gold Electrode

在N，N-二环已基碳酰亚胺（DCC）存在介质下，通过酰氨键使羧基化的多壁碳纳米管（MCNTs）与L-半胱氨酸（L-Cys）缩合，功能化的MCNTs通过S-Au键自组装（SAMs）到金电极表面，制备了修饰电极（MCNTs-L-Cys-Au／SAMs-CME），并对电极的表面结构进行电化学表征。研究表明，该修饰电极对对乙酰氨基酚的电化学氧化具有明显的催化作用。同时，对其催化氧化的机理进行了初步探讨。将此修饰电极用于流动注射不可逆双安培（FI-IB）体系的构建，即利用对乙酰氨基酚在MCNTs-L-Cys-Au／SAMs-CME上的氧化和KMnO4在另一支铂电极上的还原构建了双安培检测体系，成功的建立了在外加电压为0V条件下流动注射双安培法直接测定对乙酰氨基酚的新方法。在0V外加电压下，在0．05mol／L硫酸载液中，该氧化峰峰电流与对乙酰氨基酚浓度在2.0×10^-6～2．0×10^-4mol／L范围内呈良好的线性关系，其线性回归方程为i（nA）=8．21×10^7C＋200（r=0．9984，n=9）；在2．0×10^-4～1．0×10^-3mol／L范围内呈线性关系，其线性回归方程为i（nA）=2．30×10^7C＋10^4（r=0．9938，n=4），方法检出限为1．0×10^-6 mol／L（S／N=3）；连续测定1．00×10^-4mol／L对乙酰氨基酚标准溶液20次，电流值RSD为2．7％，进样频率为90样／h。该方法具有较高的选择性和灵敏度。对乙酰氨基酚片中的对乙酰氨基酚的含量的测定，结果比较满意。

With the aid of a condensation agent N,N-dicyclohexylcarbodimide （DCC）, the open-ended and carboxyl groups terminated multi-walled carbon nanotubes （MCNTs） and L-cysteine （L-Cys） condensation reaction through the carboxyl and amino group, and the function of MCNTs form self-assembled monolayers on gold electrode surface via bond of S-Au. A modified electrode of MCNTs-L-Cys-Au/SAMs-CME by co-assembling on gold electrode surface with MCNTs and L-Cys was prepared and it was characterized with the method of electrochemistry. The electrochemical behaviors of paracetamol show that modified electrode has great effort of electrocatalysis oxidation to paracetamol, meantime, the mechanism of electrocatalysis oxidation to paracetamol on modified electrode was studied. The analysis system is composed of electrocatalytic oxidation of paracetamol at MCNTs-L-Cys-Au/SAMs-CME and reduction of permanganate at another platinum electrode. The flow injection irreversible biamperometric analysis method was studied under the applied potential difference of 0 V. In the 0.05 mol/L sulfuric acid, the oxidative peak current increases linearly with the concentration of paracetamol in the range of 2.0×10^-6～2.0×10^-4mol/L, linear regression equation was i（nA）=8.21×10^7C＋200（r=0.9984,n=9）, and in the range of 2.0×10^-4～1.0×10^-3mol/L, linear regression equation was i（nA）=2.30×10^7C＋10^4（r=0.9938,n=4） with a sampling frequency of 90 samples per hour. The detection limit for paracetamol was 1.0×10^-6 mol/L（S/N=3） and the RSD for 20 replicate determination of 1.00×10^-4mol/L paracetamol was 2.7%. This proposed method has the advantage of high selectivity and sensitivity. The determination of paracetamol in tablets was achieved with satisfactory results.