Stusy On Electrochemical Sensitivity Of Catechol/Hexacyanoferrate Composite Film

This paper is mainly studied electrochemical sensing properties of the composite films of catechol with hexacyanoferrate modified glassy carbon electrode. The experiment was using three electrode system which has been used to conduct the electrochemical experiment by cyclic voltammetry detection of dopamine, ascorbic acid, catechol and hydroquinone. The research content includes the following three parts: 1. Catechol film modified glassy carbon electrode for dopamine and catechol detectionThe polycatechol thin film was prepared by electrochemical deposition on the glassy carbon electrode. The modified electrode was investigated by cyclic voltammetry of DA, AA two kinds of biological molecules, two isomers of catechol and hydroquinone based on electric catalytic performance. The catechol thin films have been characterized by using the scanning electron microscope(SEM), X-ray photoelectron spectroscopy(XPS). A three electrode system has been used to test DA and AA by cyclic voltammetry. The electrochemical sensor has a good linear response in the range of 10 to 100 microns concentration of DA. The modified electrodes is difficult to separate the DA and AA which are two kinds of biological molecules from the voltammograms.Detecting catechol and hydroquinone by polycatechol modified glassy carbon electrode has a good voltammetric response. The electrode measurements of catechol show good reproducibility. But when the modified electrodes was used to test catechol, the stability of the sensor proved unsatisfied. With polycatechol modified glassy carbon electrode from voltammetric peak potential difference can distinguish catechol and hydroquinone. The electrodes showed very good linear responses toward the two kinds of isomers, catechol and hydroquinone. 2. Catechol/nickel hexacyanoferrate composite modified glassy carbon electrode for the detection of dopamineThe catechol/nickel hexacyanoferrate(CC/NiHCF) composite membranes was prepared by electrochemical deposition on the glassy carbon electrode. The modified electrode was used to investigate the electric catalytic performance of two kinds of biological molecules, DA and AA by cyclic voltammetry. By using the scanning electron microscope(SEM) and X-ray photoelectron spectroscopy, the morphology and compositions of catechol/nickel hexacyanoferrate composite membranes were characterized, respectively. The modified electrode was used as working electrode with platinum as counter electrode and saturated calomel electrode(SCE) as reference electrode to constitute three electrode system. The cyclic voltammetry was used to detect the DA. The relationship between voltammetric peak current and DA concentration is the linear equation: Icurrent = 10.529 + 0.967 CDA(?A,?M). The linear correlation coefficient is 0.996. Compared with polycatechol single film modified electrodes, catechol/nickel hexacyanoferrate composite film modified electrodes showed 31 times of responds current for DA, illustrating that the CC/NiCHF modified electrodes has very high sensitivity and better linear correlation coefficient. The response currents of the catechol/nickel hexacyanoferrate composite film modified electrodes to AA was considerable with the polycatechol single film modified glassy carbon electrode. Although this modified electrode is difficult to distinguish DA and AA from the position of the peak potential, the main oxidation peak current response sensitivity of DA is 42 times higher than that of AA. 3. Catechol/cobalt hexacyanoferrate composite modified glassy carbon electrode for the detection of catecholThe catechol/cobalt hexacyanoferrate(CC/CoHCF) composite membranes was prepared by electrochemical deposition on the glassy carbon electrode. The electric catalytic performances of catechol and hydroquinone isomers were investigated with the CC/CoHCF composite film modified electrodes by cyclic voltammetry. The morphologies and compositions of the catechol/cobalt hexacyanoferrate composite membrane were characterized with the scanning electron microscope(SEM) and X-ray photoelectron spectroscopy(XPS), respectively. The modified electrode was used as working electrode, platinum was used as counter electrode and saturated calomel electrode(SCE) was used as reference electrode, which constitute three electrode system. In the range of 10 to 220 microns, the detection of catechol by electrochemical sensor has a good linear response. Compared with polycatechol single film modified glassy carbon electrode, catechol/cobalt hexacyanoferrate composite film modified electrode showed 5 times sensitivity of current response within 10 ?M-70 ?M catechol, 2 times current response within 80 ?M-220 ?M catechol. In addation, the catechol/cobalt hexacyanoferrate composite film modified electrode has a desired response toward hydroquinone. Compared with the catechol single film modified glassy carbon electrode, catechol/cobalt hexacyanoferrate composite film modified electrode gave 4 times current response in 10 ?M-60 ?M hydroquinone, 1.5 times increase of the sensitivity raised in 70 ?M-220 ?M hydroquinone.The oxidation peak of catechol is at around 0.2 V(vs. SCE), the peak of hydroquinone oxidation is about at 0.07 V(vs. SCE) on the voltammograms. The instructions of potential position can distinguish catechol and hydroquinone. In addition, the modified electrodes showed good reproducibility and stability. The modified electrodes have advantages of easy preparation, low cost, simple operation.