Voltammetric oxidation of dipyridamole in aqueous acid solutions

Abstract

A oxidação eletroquímica do dipiridamol (DIP) foi estudada em soluções aquosas acidificadas, empregando-se as técnicas de voltametria cíclica e eletrólise a potencial controlado com eletrodos de platina. Os experimentos de eletrólise foram monitorados por voltametria cíclica com ultramicroeletrodo de platina, espectroscopia de absorção óptica e fluorescência, e a integração da corrente durante a eletrólise resultou em uma carga correspondente a 2 elétrons por molécula de DIP. Os voltamogramas cíclicos registrados para o DIP a baixas velocidades de varredura se caracterizam por um único pico de oxidação em processo controlado por difusão, com o aparecimento do pico de redução correspondente a velocidades de varredura maiores que 1 V s-1. A estequiometria da reação de oxidação obtida a partir de curvas de polarização de estado estacionário resultou em ordens de reação unitária em relação ao DIP e íons H +. The electrochemical oxidation of dipyridamole (DIP) has been studied in acidified aqueous solutions at platinum electrodes employing cyclic voltammetry and controlled-potential electrolysis. The progress of the anodic oxidation as a function of time was monitored by cyclic voltammetry with platinum ultramicroelectrodes, absorption and fluorescence optical spectroscopies, the resulting integrated charge being indicative of a two electron process. The cyclic voltammograms registered for low scan speeds are characterized by a single irreversible diffusion controlled anodic wave, the related cathodic wave being also observable for scan speeds higher than 1 V s-1. Oxidation reaction stoichiommetric parameters were obtained through Tafel slopes resulting in unitary reaction orders for DIP and H + .

Maghemite-Nanoparticles Enhanced Effects in Electrochemical Determination of Dipyridamole Utilizing Simultaneous Statistical Based Experimental Design Optimization

“…About 48 coulomb of electricity was consumed for the electrochemical oxidation of 0.25 mmole of DIP. This is in agreement with the offered reaction stoichiometry based on the analysis of the slopes of Tafel plots for DIP oxidation in acidic media on the Pt electrode that shows a two electron transfer reaction 52 and is different with the oxidation process proposed in organic solvents like ethanol or acetonitrile where a two-step one electron process was found. 53 The cationic radical which is formed in the first step in these media, can be easily detected by ESR while it is not stabilized in aqueous acidic solutions.…”

“…This mechanism is consonant with the reported DIP oxidation reaction in acidic media on platinum electrode. 52 Also the positive shift of the anodic peak justified the existence of kinetic limitations in the reaction. 52 The number of electrons being transferred in the oxidation process at the MMCPE was obtained using coulometric studies for direct determination of the number of electrons.…”

Determination of dipyridamole in pharmaceutical preparations using square wave voltammetry

“…In this way, the electrochemical oxidation of DIP has been extensively studied in our laboratory in order to bring better understanding about its electrochemical reactions [4][5][6][7].…”

Quenching of Singlet Molecular Oxygen, O2(1Δg), by Dipyridamole and Derivatives

“… *Obtained from the oxidation potential vs Ag/Ag + 0.01 m Ag + in ACN in Refs. (17) and (18) by adding 0.27 V vs SCE. DIP = dipyridamole; ACN = acetonitrile. …”