A Study On The Preparation Of Carbon Nanotubes Modified Electrode And Its Applications In Pharmaceutical Analysis

With the rapid development of industrial technology, the environmental pollution is becoming more and more serious, meanwhile administrating of environmental pollution is becoming increasingly important. A fast,convenient and accurate detection of pollutants is the precondition of administrating. Carbon nanotubes (CNT) possesses peculiar electrical chemical properties. Since it was discovered by Iijima, who was working for NEC company, it has attracted great attention of scientists. In recent years many researches indicat that CNT presents great specific surface area and high electrical catalytic activity, when it acts as modified material. It has potential application prospect in the bioscience field and pharmaceutical analysis. In this thesis, multi-wall carbon nanotubes(MWNT)was worked as a modified agent. The working electrode was a glassy carbon electrode (GCE) or graphite electrode. A saturated calomel electrode (SCE) and a platinum electrode were used as the reference and the auxiliary electrode respectively. Some pharmaceutics'electro-chemical behavior has been studied with great details. The main researches were summarized as follows:The acid-treated CNT was successfully dispersed into the DMF by using ultrasound technology. A MWNT film was obtained on the GCE or graphite electrode surface via dropping supernatant method.1. In the pH=6.00 phosphate buffer solution, the chloramphenicol's electrical behavior has been studied with great details at the MWNT /GC modified electrode. The results show that: the chloramphenicol can generate a sensitive reduction peak at about -0.66V(vs.SCE) on the MWNT /GC modified electrode . The reductive peak current was linear to chloramphenicol concentration over the range from1.00×10-6 to 2.00×10-9 mol/L, the linear regression equation was ip(μA)=0.9085+2.2×104c (mol/L), regression coefficient was 0.9984, the detection limit was 4.40×10-10 mol/L. The reduction of chloramphenicol was attributed to adsorption controlling process at MWNT /GC modified electrode. The transmitted electron number 2 was calculated by LAVIRON formula. By the linear relationship of peak potential and pH, it can be inferred thatthe transmitted number of electron and proton were equal. So the electrode reaction contains two electrons and two protons process.2. In the pH=7.00 phosphate buffer solution, a detailed study of diethyl stilbestrol's electrical behavior has been done at the MWNT /graphite modified electrode. The results show that: the diethyl stilbestrol can generate a sensitive oxidation peak at about +0.375V(vs.SCE) and a weak reduction peak at about +0.095V(vs.SCE) on the MWNT /graphite modified electrode respectively. The oxidative peak current was linear to diethyl stilbestrol concentration over the range from 2.00×10-8 to 4.00×10-5 mol/L, the linear regression equation was ip(μA)= 5.74+10.377×106c (mol/L), regression coefficient was 0.994, the detection limit was 5.00×10-9 mol/L . The oxidation of diethyl stilbestrol was dependent on adsorption controlling process at MWNT /graphit modified electrode. The transmitted electron number, 2, was calculated by LAVIRON formula. By the linear relationship of peak potential and pH, it can be inferred that the transmitted number of electron and proton were equal. So the oxidation of diethyl stilbestrol was that two phenolic hydroxyl groups were oxidated to carbonyl group by two electrons and two protons process.3. In the pH=7.00 phosphate buffer solution, the ethinylestradiol's electrical behavior has been studied in a detailsed way at the MWNT /graphite modified electrode. The results show that: the ethinylestradiol can generate a sensitive oxidation peak at about +0.550V (vs.SCE) on the MWNT /graphite modified electrode. The oxidative peak curent was linear to diethyl stilbestrol concentration over the range from 1.00×10-6 to 2.00×10-4 mol/L , the linear regression equation was ip(μA)= 2.4144+4.55×104cmol/L), the detection limit was 3.00×10-7 mol/L . The oxidation of ethinylestradiol was attributed to adsorption controlling process at MWNT /graphit modified electrode. The average recovery of simulated wastewater was 103%. The transmitted electron number, 2, was calculated by LAVIRON formula. By the linear relationship of peak potential and pH, it can be obtained that the transmitted number of electron and proton were equal. So the oxidation of ethinylestradiol was that phenolic hydroxyl group was oxidated to carbonyl group by single electron and single proton process.