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Preparation and Investigation of Electrochemical Sensors for Determination of Pharmaceutical and Biological Compunds Based on Glassy Carbon Electrode Modified with Polypyrrole/Carbon Nanotube Composite

Azimzadeh Sani, Mahnaz | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46177 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Shahrokhian, Saeed
  7. Abstract:
  8. In the recent years, conductive polymers are widely used in the design and construction of chemical and biological sensors.The polypyrrole due to features such as good thermal and chemical stability, ease of synthesis and better conductivity than other conductive polymers, atracts much attention. In order to modification of electrode surface,adhesiveand thin polymer films can be electropolymerized in the presence of organic or inorganic dopants on the surface of metal or carbon surfaces in aqueous or organic solutions. On the other hand carbon nanotubes by owing unique properties such as chemical stability and high electrical conductivity are good choice for electrod surface modification. Therefore by adding carbon nanotubes to a polymer, features of both components get together and the outcomehas better mechanical properties, electrical conductivity and catalytic activity than each component alone.Because of importance of analysis of trace amounts of pharmaceutical and biologicalcompunds,preparation and investigation of sensitive electrochemical sensors for determination of pharmaceutical and biological compunds based on glassy carbon electrode modified with polypyrrole/carbon nanotube compositein the presence of different dopants is the purpose of this study.In the first work a glassy carbon electrode was coated with a thin layer of MWCNTs and subsequently was electro-polymerized with polypyrrole. The prepared electrode is used for the voltammetric determination of olanzapine (OLZ). The results indicate a remarkable increase in the peak current of OLZ on the surface of the modified electrode. Experimental variables, such as the deposited amount of nanotube suspension, pH of the supporting electrolyte, potential and time of the accumulation and the number of electro-polymerization cycles were optimized by monitoring the LSVs toward OLZ. In the optimal conditions, the electrode shows a linear response to the concentration of OLZ within 0.02–2.00 µM with a detection limit of 6.00 nM. The modified electrode has been applied for accurate determination of the trace amounts of OLZ in pharmaceutical and clinical preparations.In the second work a voltammetric sensor based on glassy carbon electrode modified with a thin film of MWCNTs coated with an electropolymerized layer of tiron-doped polypyrrole was developed and the resulting electrode was applied for the determination of acyclovir (ACV). The electrochemical performance of the modified electrode was investigated by means of LSV. The effect of experimental variables, such as pH of the supporting electrolyte, drop size of the cast MWCNTs suspension, number of electropolymerization cycles and accumulation time were optimized by monitoring the LSVs of the modified electrode toward ACV. The best response was observed at pH 7.0 after accumulation at open circuit for 160 s. Under the optimized conditions, a significant electrochemical improvement was observed toward the electrooxidation of ACV on the modified electrode surface relative to the bare GCE, resulting in a wide linear dynamic range (0.03–10.0 μM) and a low detection limit (10.0 nM) for ACV. The sensor provided satisfactory results for the determination of ACV in pharmaceutical and clinical preparations
  9. Keywords:
  10. Carbon Nanotubes ; Polypyrrole ; Composite ; Modified Electrodes ; Electrochemical Sensor ; Voltammetric Measurement ; OLanzapine (OLZ) ; Acyclovir (ACV)

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