Preparation Of Chemical Modified Electrodes And Their Applications In Analytical Chemistry

This article described in detail the types, preparation methods and applicable value of modified electrodes, especially in the field of analytical chemistry. Using functional material like carbon nanotubes, 4-Aminobenzoic acid, mercaptoacetic acid, metal hexacyanoferrates etc. as the modified agents, new interfaces were constructed at the electrode surface. Electrochemical behaviors and their applications of the resulting modified electrodes were studied. The main research work was as follows:1. Voltammetric determination of chloramphenicol using glassy carbon electrode modified with multi-wall carbon nanotubesCarbon nanotube was purified and dispersed in anhydrous alcohol, then as the modified material, it was dipped on the glassy carbon electrode to prepare chemical modified electrode. A sensitive electrochemical method was developed for determination of chloramphenicol (CAP) using a glassy carbon electrode modified with multi-wall carbon nanotubes (MWNTs) film. In 0.1 mol/L KCl-HCl solution of pH 2.0. A sensitive cathodic peak of CAP on the MWNTs modified electrode was obtained at around -0.36 V (vs. Ag/AgCl). Under the optimum conditions, the reduction peak current was linearly proportional with the concentration of CAP over the range of 6.0×10-6 to 2.7×10-4 mol/L with a detection limit of 3.0×10-6 mol/L. The proposed method is sensitive and accurate, and can be applied to determine CAP in simulated samples and real samples with satisfactory results.2. Assembly of metal hexacyanoferrates films immobilized on mercaptoacetic acid modified gold electrode and their applications in electroanalytical chemistry An electroactive metal hexacyanoferrates (MHCF, M=Ni2+ or Co2+) films through layer-by-layer assembly based on electrostatic attraction on the mercaptoacetic acid (MA) modified gold electrode. Experiments showed that the modified electrode exhibited selected response to these ions and exhibited a near-Nernstian response to K+. What's more, it could catalyze the oxidation of AA and S2O32- in KCl solution. All these electrodes prepared exhibited good stability.3. Electrocatalytic oxidation of formaldehyde on methylene blue and nano-Au modified glassy carbon electrode4-Aminobenzoic acid (4?ABA) was covalently grafted on a glassy carbon electrode (GCE) to form a negatively charged surface, and cationic methylene blue was linked by electrostatic adsorption as an electron transfer mediator. The nano-Au was assembled on the electrode was linked by Au?S and Au?N covalent bond and electrostratic adsorption. The electrode had better catalytic oxidation to the formaldehyde (HCHO) in the alkalinemedia. The HCHO appeared two oxidation peaks at +0.13 V and +0.28 V, the former oxidation peak used to determine the concentration of HCHO range of 10 ~ 125 mg/L with a detection limit of 0.5 mg/L.