الفهرس 
Chapter IOnly 14 pages are availabe for public view
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Abstract
The interaction of antipyrine (AnP) with the double-stranded deoxyribonucleic acid of salmon sperm (ss dsDNA) in solution and immobilized on a glassy carbon electrode (GCE) was carefully examined using voltammetric methods. The UV-vis absorption spectroscopic method was also used to screen the interaction between AnP and dsDNA in solution. AnP showed a single anodic peak in phosphate buffer solutions (pH 3.5 - 9.5). AnP is oxidized in a diffusion-controlled process from a phosphate buffer solution, pH 7.4. The variation of the current signals of AnP was monitored in the presence of ss dsDNAusing bare GCE in coupling with differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The diffusion coefficient of free AnP was 3.7×10-6 and 2.8×10-7 cm2 s-1 for the AnP-DNA complex. The binding constant was calculated to be 1.5×105 and 1.1×105 M-1 in pH 7.4, using DPV and UV/vis spectroscopy, respectively. AnP binds to DNA primarily by electrostatic interaction with a contribution from intercalation. A detection pattern based on pre-concentration and DPV detection at GCE modified with dsDNA was introduced to determine AnP in saliva samples. The electrochemical oxidation of diflunisal at glassy carbon electrodes (GCE) in Britton-Robinson buffer (BR) solutions over the pH range 2.0-12.0 was studied using cyclic voltammetry (CV) and Differential pulse voltammetry (DPV). A single irreversible oxidation peak was observed. The differential pulsed voltammetric peak current of diflunisal on the glassy carbon electrode was significantly improved due to the adsorption of diflunisal on the glassy carbon surface. The differential pulse discharge (DPASV) method was developed to determine diflunisal under optimal conditions. Adsorption was also controlled within the pH range of 4.0-9.0. A sensitive and selective quantitation of diflunisal was performed by adsorption stripping voltammetry. Analyte accumulation was performed in Britton-Robinson buffer (pH 5.0) at a voltage of -0.3 V (versus Ag-AgCl-KClsat) for 300 s and measurement was performed, after medium exchange, in BR buffer of pH 7.0 using a DPV. This format has been applied satisfactorily to the determination of diflunisal in cow’s milk.