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A chemically modified electrode was prepared by incorporating p-aminophenol into multiwall carbon nanotubes paste matrix. Cyclic voltammetry, square wave voltammetry, double potential step chronoamperometry, and electrochemical impedance spectroscopy were used to investigate the electrochemical behaviour of glutathione at the chemically modified electrode prepared. According to the results, p-aminophenol multiwall carbon nanotubes paste electrode (p-APMWCNTPE) showed high electrocatalytic activity for glutathione oxidation, producing a sharp oxidation peak current at about +0.285 vs Ag/AgCl reference electrode at pH 5.0. Chronoamperometry was also used to determine glutathione's catalytic rate constant and diffusion coefficient at p-APMWCNTPE. The square wave voltammetric peak current of glutathione increased linearly with glutathione concentration in the range of 2.0 × 10(-7) - 1.0 × 10(-4) mol L(-1) with a detection limit of 9.0 × 10(-8) mol L(-1). The method was also successfully employed as a selective, simple, and precise method for the determination of glutathione in haemolysed erythrocyte, tablet, and urine samples.

In the present work, electrochemical synthesis of novel pyrimido[4,5-b]indoles was directly carried out via the electrochemical oxidation of catechols in the presence of 2,4-diamino-6-hydroxypyrimidine in an aqueous media. The results suggested that electrogenerated o-benzoquinone moieties participated in the Michael-type addition reaction with 2,4-diamino-6-hydroxypyrimidine via the ECEC mechanism. These new compounds were synthesized in high yields and purity in an aqueous solution without toxic reagents or catalyst and with high atom economy in ambient conditions.

A polymerized film of 2-hydroxy-1-(1-hydroxynaphthyl-2-azo)-naphthalin-4-sulfonic acid (HHNANSA) was prepared at the surface of a glassy carbon electrode by electropolymerization. The modified electrode was used for the simultaneous determination of dopamine (DA) and uric acid (UA). The electrochemical behaviors of the compounds at the surface of the modified electrode were studied using cyclic voltammetry, chronoamperometry, and square wave voltammetry (SWV). The experimental results indicated that the modified electrode exhibited an efficient electrocatalytic activity towards the oxidation of DA and UA, with a peak separation of about 140 mV at pH 5.0. Using chronoamperometry, the catalytic reaction rate constant was measured and found to equal to 1.23×10 4 mol -1 L s -1 . At pH 5.0, the catalytic peak currents linearly depended on the DA and/or UA concentrations in the range of 1.0-300 µmol L -1 DA (two linear segments with different slopes) and 6.7-20 µmol L -1 UA, using SWV. The detection limits for DA and UA were 0.25 and 1.17 µmol L -1 , respectively. The RSD % for 40.0 and 140.0 µmol L -1 DA were 1.9 and 2.2 %, respectively, whereas for 10.0 and 20.0 µmol L -1 UA, they were 1.8 and 1.2 %, respectively. The modified electrode showed good sensitivity, selectivity, and stability. It was successfully applied for the determination of DA and UA in real samples, such as drugs and urine.

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In order to synthesize some of new 6-amino-5-hydroquinone-1,3-dimethyluracil derivatives, the electrochemical oxidation of hydroquinones (1a-c) was carried out in the presence of 6-amino-1,3-dimethyluracil as a nucleophile in an aqueous phosphate buffer solution. The results show that electrogenerated p-benzoquinone moieties (1a -c ) participate in the reaction with 6-amino-1,3dimethyluracil via the EC mechanism to form the corresponding uracil derivatives (3a-c). The electrosynthesis of these compounds (3a-c) was performed successfully in an aqueous solution at carbon rod electrodes, without using any toxic reagents, catalyst or solvents and the products were finally produced in high yield and purity. The proposed method has a novel viewpoint in the synthesis of potential anticancer/antiviral uracil-base drugs.