Detections Of Hydrogen Peroxide, Copper Ion And Glucose Based On Poly (Azure A) Modified Electrode

The basic principles, research progresses and applications in analytical chemistry of electrochemical sensors, chemical modified electrodes and conducting polymer films were introduced in this thesis. Poly（azure A） modified glassy carbon electrode was fabricated. The quantitative detections of hydrogen peroxide and copper ions were achieved based on Fenton-type reaction. A non-enzyme glucose sensor was developed by employing the redox reaction of nikel ions modified on the electrode surface. The main contents are listed as follows.1. A glassy carbon electrode modified with poly（azure A）（PAA）, chitosan（CS） and copper ions, GCE/PAA-CS/Cu, was prepared by a two-step method, displaying a good electrochemical activity owing to the stable complexing between Cu²⁺ and PAA-CS film. Hydroxyl radicals derived from the Fenton-type reaction between Cu²⁺ and H₂O₂ could effectively oxidize poly（azure A）, leading to the great reduction-current change of the dye polymer in the electrode process. The fabricated electrode displayed a linear response in the H₂O₂ concentration range from 0.002 to 0.5 m M and that from 2.56 to 25.0 m M with a detection limit of 0.7 mM estimated at a signal-to-noise ratio of 3. The good analytical performance including low detection limit, fast response time, low cost, good anti-interference performance, satisfying stability, acceptable repeatability and reliable reproducibility were found from the proposed amperometric sensor, suggesting that the current work could provide a feasible approach for the non-enzymatic H₂O₂ detection.2. Poly（azure A）（PAA） modified glassy carbon electrode was prepared by cyclic voltammetry. Copper ions acted as a mimic peroxidase in view of this organic dye polymer exhibited a limited catalytic ability for the reduction of H₂O₂. They induced the decomposition of H₂O₂ due to Fenton-type reaction and produced highly reactive hydroxyl radicals that could effectively oxidize PAA and lead to the great increase of the reduction current of the dye polymer in the cyclic voltammetric scan. An indirect and sensitive method for the trace Cu²⁺ detection was developed. The fabricated sensor displayed a linear response in the Cu²⁺ concentration range from 50 n M to 10 μM and that from 10 μM to 100 μM with a detection limit of 8.4 n M estimated at a signal-to-noise ratio of 3. The interference experiments show that some common metal cations had little influence on the electrochemical measurement. The proposed method was successfully applied to the determination of copper ions in water samples and the recovery values were found to vary from 95.4% to 108%.3. Poly（azure A） was generated on the GCE surface by using the CV scan but it exhibited no catalytic ability to the oxidation of glucose. GCE/PAA-Ni was fabricated owing to the binding of nickel with the dye polymer. This nickel modified electrode presented a transformation derived from the Ni（II）/Ni（III）, and showed a good electrocatalytic activity for oxidation of glucose in alkaline medium. An sensitive and selected non-enzyme glucose sensor was developed. It exhibited a broad linear calibration range of 5 μM-12 m M for quantification of glucose and a low detection limit of 0.64 μM（3σ）. Moreover, the excellent analytical performance including fast response time, good anti-interference ability, satisfying stability and reliable reproducibility were also found from the proposed amperometric sensor. The results were satisfactory for the determination of glucose in human serum samples as comparison to those from a local hospital.