The Preparation And Its Application Of Nanomaterials/Amino Acid Chemically Modified Electrode

Chemically modified electrodes (CMEs), the most important tool in electroanalytical chemistry, show the unique advantages in selectivity and sensitivity. It has been widely applied in analytical science, life science, environmental science, materials science and other fields. With the development of nanomaterials, it is widely used for developing CMEs and can further improve the performance of electrode. Nanomaterials, due to their unique properties, have attracted much attention in the field of electrochemical sensor. Nanomaterials can not only increase surface area and conductivity of modified electrodes, but also show catalytic effect toward some anlyte. In this thesis, we fabricated some modified electrodes based on muti-walled carbon nanotubes, gold nanoparticles and L-cysteine. The main results are expressed as follows:1. A novel voltammetric sensor using multi-wall carbon nanotubes (MWCNTs) coupled with Nafion modified glassy carbon electrode (GCE) was developed for the detection of methylparaben (MP). This sensor exhibited good electrocatalytic activity toward the oxidation of MP in the phosphate buffer solution (PBS, pH6.5). Under the optimum conditions, the anodic peak currents of MP were linearly relationship with MP concentrations in the range of3.0×10"6mol L’1-1.0x10-4mol L-1. The detection limit was1.0×10-6mol L-1. The proposed method was successfully applied to determine MP in cosmetic with satisfactory results.2. A glassy carbon electrode was modified with L-cysteine by cyclic voltammetry. The modified electrode was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and used as a voltammetric sensor in detecting Sunset Yellow. Under the optimum experimental conditions, the modified electrode showed a linear voltammetric response for Sunset Yellow in the range of8.0x10’9～7.0×10-7mol L-1with a detection limit of4.0x10-9mol L"1. Under the presence of3.0×10’7mol L"1tartrazine, the linear relationship between peak current and concentration of sunset yellow was1.0x10-8～5.0x10"7mol L"1, with a detection limit of6.0x10-9mol L-1. The method was applied successfully to detect Sunset Yellow in a drink sample, and provided the same analytical result as the UV reference method.3. A novel voltammetric sensor for Salbutamol was fabricated via the self-assembly of L-cysteine and Nano-Au on MWCNTs-Nafion-membrane. This sensor exhibited excellent activity toward the oxidation of Salbutamol. The electrochemical behaviors of Salbutamol were investigated and some kinetic parameters were calculated using various electrochemical techniques. Under selective conditions, the detect linear range was2.0x10"7～7.0x10-6mol L-1with a detection limit of9.0×-8mol L-1...