الفهرس 
Summary
Biological importance of neurotransmitterOnly 14 pages are availabe for public view
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Abstract
Catecholamine neurotransmitters belong to a biologically important group of compounds which are mediators in transmitting messages between neurons. Therefore, the development of a simple, sensitive and accurate method for Catecholamine neurotransmitters determination is an important task in current neurochemistery. There is considerable interest in developing electrochemical techniques for measurement of neurotransmitters since the electrochemical methods have more advantages over various analytical methods because the electrodes can be made conveniently to sense the neurotransmitters. Moreover, the voltammetric methods have been used for the determination of different Catecholamines.
The thesis includes three chapters:
1- The first chapter includes definition of neurotransmitters and introduction of their biochemical importance in neurotransmission processes. Also, this chapter contains some fundamental concepts of electroanalytical methods e.g. stripping and cyclic voltammetric methods. Finally, this chapter includes a literature survey on the determination of neurotransmitters (Dopamine and L-dopa) using different voltammetric analytical methods at chemically modified solid electrodes.
2- The second chapter includes the experimental part which involves the preparation of stock solutions, reagents and instruments used in this investigation. Also, it includes the procedures and conditions used for stripping voltammetric measurements of neurotransmitter compoundsand their applications.
3- The third chapter includes the results and discussion for the voltammetric behavior of Dopamine and L-dopa using polysulphacetamide modified glassy carbon electrode.
3.1. Electropolymerisation of sulfacetamide (SFA) at the glassy
carbon electrode (GCE) surface and mechanism
This part of investigation discusses:
• The electrochemical oxidation of sulphacetamide on glassy carbon electrode.
• The Effect of acid concentration, initial potential, concentration and scan rate on current peak of sulfacetamide.
• Mechanism of Formation of polySFA on GCE
3.2. Voltammetric behaviour of dopamine (DA) on SFA modified GCE.
This part of investigation discusses:
• The electrochemical oxidation of DA on the bare and SFA-modified GCE.
• The effect of supporting electrolyte, pH, accumulation potential, accumulation time and scan rate on the current response for DA were investigated.
Under the optimum conditions, the effect of concentration of DA on the anodic current response was performed. In 0.01M Britton-Robinson buffer( pH 5), accumulation time 30 second and scan rate 10 mVs-1. A linear behavior was observed in two ranges: 1×10-8 to 7×10-8 M and 1×10-7 to 6×10-7 M. In the first range, the linear regression equation ip (nA) = 81.429x108 C(M) +10.714. In the second range the following linear regression equation: ip (nA) = 22.486x107C(M) +676.33. The correlation coefficient for the first linear relation is R2=0.995 and for the second relation it is R2= 0.997. The detection limit (LOD) and quantification limit (LOQ) in the lower range are 0.13x10-10 M and 0.43x10-10 M respectively.
• The reproducibility of the results was investigated by carrying out five successive measurements of 1×10-8 M DA after accumulation time 30 second at optimum condition. The relative standard deviation was calculated and was found to be 3.5%.
• The influence of AA, UA and glucose on the current response of DA concentrations were investigated individually and then DA was determined in the presence of these interferences.
• DA has been determined in spiked biological samples.
3.3. Voltammetric Behaviour of L-dopa on SFA modified GCE.
This part of investigation discusses:
• The electrochemical oxidation of L-dopa on the bare and SFA-modified GCE.
• The effect of supporting electrolyte, pH, accumulation potential, accumulation time and scan rate on the current response for L-dopa were investigated.
• Under the optimum conditions, the influence of concentration of L-dopa on the anodic current peak was tested. In 0.01M Britton-Robinson buffer (pH2), accumulation time 30 second and scan rate 10 mVs-1. A linear behavior was observed over the range 1×10-7 to 1.1×10-6 M with a correlation coefficient 0.998. The detection limit of L-dopa was found to be 0.3×10-9 M.
• The reproducibility of the results was investigated by carrying out five successive measurements of 1×10-7 M L-dopa after accumulation time 30 seconds at optimum condition. The relative standard deviation was calculated and was found to be 4.5%.
• The effect of AA, UA and glucose on the current response of L-dopa concentrations were investigated individually and then L-dopa was determined in the presence of these interferences.
• L-dopa has been determined in spiked biological samples.