Study On The Electrochemical Sensing Of Aminated Glassy Carbon Electrode And Its Electrocatalytic Mechanism

Chemically modified electrodes (CME) can effectively change the carbon material surface and electron transfer properties, exhibiting superior sensitivity and electro-catalytic properties. It was widely used in biological samples analysis, environmental monitoring, food testing, health care, clinical testing and other fields. The nitrogen atoms introduced to carbon materials through C-N bond which has unique advantages in improving the selectivity and sensitivity of the carbon materials. In this paper, we use a moderate and simple electrochemical method for ammoniating glassy carbon electrode. And its application in selective detecting of ascorbic acid, the electrochemical behavior of nitrite and direct electron transfer of glucose oxidase. And we also study the catalytic mechanism of ascorbic acid and nitrite on aminated glassy carbon electrode. Specific as follows:First, the AGCE through the method of electrolysis was made. In additional, the electrochemical behavior of ascorbic acid (AA), dopamine (DA), uric acid (UA) and three components exist at the same time was studied. Experimental results show that AGCE varying degrees, respectively, changed the over-potentials and electron transfer rates of AA, DA and UA on AGCE surface, which can effective select detecting AA. Enabling detect any one component or the simultaneous determination of three components, and applying it to testing AA in human serum and urine samples with satisfactory results.Second, the AGCE through electrolysis approach which is a facile, simple and easy-control shows favorable electrocatalytic property towards the oxidation of nitrite. Using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studied the electrochemical behavior of sodium nitrite on the AGCE. Under the optimum conditions, the oxidation potential of sodium nitrite negative to 0.72V. The current of differential pulse voltammetric peak of nitrite at the AGCE is proportional to the concentration of nitrite over the range of 1.0×10-6-7×10-4M with a low detection limit of 1.3×10-8 M. AGCE exhibited good electrocatalytic performance, high reproducibility, stability, high selectivity and was successfully applied in river water and rain water. This research provides optional and simple without enzyme method for food with nitrite safety. At the same time, provides a chemical basis for the study of disease pathology caused by nitrite.Third, using 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to activate carboxyl groups in the glucose oxidase. Then the glucose oxidase was in combination with aminated GCE and the AGCE was prepared. The immobilized GOD displayed a pair of well-defined and nearly reversible redox peaks with a formal potential of -0.460 V. Under optimal experimental conditions, it was found that the reductive peak current is linearly increased with the increase in glucose concentration ranging from 50 μM to 1000 μM with a correlation coefficient (R) of 0.9906 and the detection sensitivity is 4.08μA/mM. In addition, the sensor has good stability, high selectivity characteristics, provides a simple and rapid new method for testing glucose.