The Application Of Modified Carbon-based Electrodes In Electroanalysis

The aim of chemically modified electrodes (CMEs) was according our demandsto adhere some materials with excellent properties or functional materials on theelectrode surface by using different methods. CMEs have shown splendid prospects insensitivity and selectivity. In this paper, different modified electrodes have beenprepared, and its application in separation and detection were studied.1. This paper first reported that hydroquinone (HQ) and catechol (CC) can beseparated and detected simultaneously by means of a graphite electrode (GE) whichwas modified by constant potential in0.5mol/L H2SO4solution. Compared with thebare GE, the electrode showed high sensitivity, reversibility and selectivity towardsthe oxidation of hydroquinone (HQ) and catechol (CC) in0.1mol/L phosphate buffersolution (PBS, pH7.0). The oxidation over potentials of HQ and CC decreasedsignificantly and the corresponding oxidation currents increased remarkably. In thepresence of1×10-4mol/L isomer, the oxidation peak current of HQ and CC werelinear over the range from2×10-6to1×10-3mol/L and from5×10-6to3.5×10-4mol/L,respectively. The detection limits (S/N=3) for HQ and CC were1.6×10-7mol/L and3.9×10-7mol/L, respectively. Moreover, the practical sample was detectedsuccessfully by this modified electrode.2. Simultaneous seperation of AA, DA and UA by Cyclic voltammetry and linersweep voltammetry at the graphite electrode (GE) which was modified by constantpotential in0.5mol/L H2SO4solution. Compared with the bare GE, the electrodeshowed high sensitivity and selectivity towards the oxidation of AA, DA and UA. Inthe presence of1×10-4mol/L DA and3×10-5mol/L UA, the oxidation peak current ofAA were linear over the range from5×10-5to4.5×10-3mol/L. The detection limits(S/N=3) were1.4×10-6mol/L. The oxidation peak current of DA were linear over therange from1×10-6to4×10-4mol/L coexisted with6×10-4mol/L AA and3×10-5mol/LUA. The detection limits (S/N=3) were8.2×10-8mol/L. The oxidation peak current ofUA were linear over the range from5×10-7to1.5×10-4mol/L coexisted with6×10-4mol/L AA and3×10-5mol/L DA. The detection limit (S/N=3) was2.5×10-8mol/L.Moreover, the practical sample was detected successfully by this modified electrode.3. The polyglycine modified graphite electrode (GE) was prepared, and thedetection of ofloxacin was studied at the modified electrode by cyclic voltammetry. The modified electrode showed good stability and excellent catalytic activitiestowards the oxidation of Ofloxacin. The oxidation currents increased remarkablycompared with that obtained at the bare GE. Studied some factors which influencingthe determination of Ofloxacin. Under the optimized condition, the oxidation peakcurrent of ofloxacin were linear over the range from4×10-7to1×10-5mol/L and thedetection limit(S/N=3) was3.6×10-8mol/L. The average recovery was97.2%. Theelectrode has good reproducibility and high sensitivity, and can be applied for routineanalysis of ofloxacin medicaments.4. The behavior of dienestrol at the graphene modified glassy carbon electrodewas studied for the first time. The optimal determination condition was selected bycyclic voltammetry. Compared with bare glassy carbon electrode, the modifiedelectrode had good electrical catalysis and high sensitivity for the determination ofdienestrol. The oxidation peak current of dienestrol were linear over the range from1×10-6to8×10-5mol/L and the detection limit (S/N=3) was1.8×10-7mol/L.