| Part 1. Simultaneous electrochemical determination of dopamine, ascorbic acid and uric acid using poly(acid chrome blue K) modified glassy carbon electrodeA novel polymerized film of acid chrome blue K (ACBK) was prepared on the surface of a glassy carbon electrode (GCE) by electropolymerization, and then the modified electrode was successfully used to simultaneously determine dopamine (DA), ascorbic acid (AA) and uric acid (UA). The characterization of electrochemically synthesized poly-ACBK film was investigated by atomic force microscopy (AFM), attenuated total reflection (ATR–FTIR), electrochemical impedance spectroscopy (EIS) and voltammetric methods. The poly-ACBK modified GCE exhibited excellent electrocatalytic activity towards the oxidations of DA, AA and UA in 0.05mM phosphate buffer solution (pH 4.0). The separations of anodic peak potentials of AA/DA, DA/UA and AA/UA on this modified electrode are 193, 166 and 359mV in DPV, respectively. Under the optimum conditions, the calibration curves for DA, AA and UA were obtained in the range of 1.0–200.0, 50.0–1000.0 and 1.0–120.0μmol·L?1, respectively. The detection limits (S/N = 3) were 0.5, 10.0 and 0.5μmol·L?1 for DA, AA and UA, respectively. With good selectively and sensitivity, the present method was applied to the determination of DA in dopamine hydrochloride injections, AA in vitamin C tablets and UA in urine samples. Part 2. Sensitive determination of adenine on poly(amidosulfonic acid) modified glassy carbon electrodeA novel and reliable direct electrochemical method was established for the detection of adenine, based on the differential pulse anodic stripping response at a poly(amidosulfonic acid) (poly-ASA)-modified glassy carbon electrode (GCE) fabricated by electropolymerization. The characterization of electrochemically synthesized poly-ASA film was investigated by atomic force microscopy and electrochemical impedance spectroscopy.This poly-ASA-modified GCE could greatly enhance the detection sensitivity of adenine. At optimum conditions, the anodic peak exhibits a good linear concentration dependence in the range from 3.0×10?8 to 1.0×10?6 mol·L?1 (r=0.9994). The detection limit is 8.0×10?9 mol·L?1 (S/N=3). The proposed method could be used to determinate the adenine in tablets of vitamin B4 with satisfactory results.Part 3. Selective determination of dihydrogen phosphate using cobalt membrane modified carbon fiber microelectrodeIn this work, a highly selective and sensitive dihydrogen phosphate membrane sensor based on cobalt membrane modified carbon fiber microelectrode is reported. On optimal conditions, the sensor shows a linear dynamic range between 1.0×10?6 and 1.0×10?3 mol·L?1, with a nice Nernstian behavior in pH of 4.0. The detection limit of the electrode is 6.0×10?7 mol·L?1. The sensor possesses the advantages of short response time, good reproducibility, stability and selectivity. Part 4. The development and application of phosphate anion ion sensitive electrodeSol-gel containing cobalt phosphate membrane modified glassy carbon electrode was prepared, which showed Nemstian response for PO43?in the concentration range of 10?8 ~ 10?4 mol·L?1 with a slope of 14.5 mV·dec?1. Performance parameters of the modified electrodes were studied. This modified electrode was characterized by its simple preparation, high sensitivity, good stability and reproducibility, as well as fast response. In the end, this proposed method was successfully applied to determine the concentration of PO43? in soil samples. |
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