| Ionic liquids, named as room temperature molten salts, are organic compounds which composed of organic cations and inorganic or organic anions. They are liquds at room temperature or close to room temperature, and have been used widely in electrochemical fields because of their unique electrochemical properties of good conductivity, wide electrochemical windows and high viscosity. In this thesis, four kinds of modified electrodes based on ionic liquid are fabricated and utilized to investigate electrochemical behaviors of two proteins, AA and DA. The new voltammetry methods for determination of AA and DA are established. The studies have scientific significance to expand the application range of ionic liquids and enrich electrochemical research contents. The thesis consists of four chapters. The main contributions are summarized and presented as follows:The ionic liquid 1-butyl-3-methylimidazoiium hexafluorophosphat ([BMIM]PF6) is used as binder to prepare ionic liquid carbon paste base electrode ([BMIM]PF6-CPE). The Nafion/AuNPs/[BMIM]PF6-CPE is fabricated by layer-by-layer assembly of AuNPs and nafion to investigate the electrochemical behaviors of dopamine (DA). The results suggest that a pair of redox peaks of DA is observed at Nafion/AuNPs/[BMIM]PF6-CPE,peak-to-peak separation and the electron transfer rate constant (ks) of DA are 0.129 V and 0.71 s-1, respectively. In addition, the peak currents of DA are proportional to its concentrations from 5.0×107 to 1.0×105 mol·L1 with the detection limit of 2.0×10-7 mol·L-1(S/N=3).The method has been applied to determine DA in the hydrochloride dopamine injection samples and a satisfying result is obtained.The modified glassy carbon electrode ([C14mim]PF6-CS/GCE) is fabricated by the composite of ionic liquid 1-tetradecyl-3-methylimidazolium hexafluorophosphate ([C14mim]PF6) and chitosan (CS). The electrochemical behaviors of DA and ascorbic acid (AA) are investigated at [C14mim]PF6-CS/GCE. A new method has been established for the simultaneous determination of AA and DA at the modified electrode. The results show that the oxidation peaks of AA and DA can be separated completely (ΔEp = 0.385 V) at [C14mim]PF6-Chit/GCE.The peak currents of AA and DA are proportional to their concentrations in a range of 2.6×10-5-1.0×10-3 mol·L-1 and 1.3×105-5.2×104 mol·L-1, respectively.The composite film is prepared by combining 1-butyl-3-methylimidazolium trifluoroacetate ([BM1M]TA) with hyaluronic acid (HA). The modified electrodes of Cyt c-HA-[BMIM]TA/GCE and Mb-HA-[BMIM]TA/GCE are fabricated by embedding Cyt c and Mb in the composite film and casting them on the surface of GCE, respectively. The characters of two modified electrodes are investigated using electrochemical and spectrometric methods. The results indicate that Cyt c and Mb can retain their activity in the composite film and realize their direct electrochemistry. Both of the modified electrodes exhibit excellent electrocatalytic activity toward the reduction of H2O2.The catalysis current are linear to H2O2 concentration in the range of 3.0×10-6-1.2×10-4 mol·L-1 at Mb-HA-[BMIM]TA/GCE and 3.0×10-6-1.0×10-4 mol·L-1 at Cyt c-HA-[BMIM]TA/GCE, respectively.
|
PDF Full Text Request