Glassy carbon electrode modified with COOH- and NO2-functionalized polyspyrophosphazenes were used to study the redox process of a electroactive probe (ferrocene) in non-aqueous electrolyte. The electrochemical behavior of polyphosphazenes substituted with COOH and NO2 groups has been studied using cyclic voltammetry. Their blocking properties depend on the substituent group and on the substitution/nitration degree. The oxoreduction of the couple Fc/Fc+ occurs with rapid redox kinetic at the modified glassy carbon electrode with high nitration degree NO2−functionalized polyspyrophosphazene. The polymers were immobilized on the glassy carbon surface at different concentrations to study surface charge density effect. In this report were studied the reproducibility, repeatability and stability of the modified electrodes.

Cyclic voltammetry was used to study the electrochemical behavior of new 1,5-benzodiazepine derivatives on a glassy carbon electrode. Well-defined oxidation peaks were observed in DMSO. The Electrochemical response of the glassy carbon electrode was evaluated as function of the scan rate, showing that the electron transfer process for compound (5) and (6) resulted to be controlled by diffusion.

1-Metil-4-nitro-2-bromometilimidazol (4-NimMeBr) foi eletroquimicamente reduzido em eletrodos de mercúrio, carbono vítreo e carbono vítreo modificado com nanotubos de carbono de parede múltipla (MWCNT). 4-NimMeBr adsorveu no eletrodo de carbono vítreo modificado com nanotubos de carbono, tornando possível a implementação de um método de quantificação por voltametria de redissolução adsortivo (ASV). 4-NimMeBr foi usado como protótipo de composto eletroativo para estudar o efeito do tamanho dos nanotubos e de sua funcionalização por oxidação, na resposta eletroquímica do eletrodo modificado. Nanotubos oxidados formaram melhores dispersões em água, produzindo uma superfície de eletrodo com alta densidade de MWCNT, como mostram os dados obtidos por microscopia de varredura eletroquímica (SECM). Sob as condições otimizadas, a corrente de pico foi proporcional à concentração de 4-NimMeBr no intervalo de 10-6 mol L-1 a 10-4 mol L-1 com limite de detecção e quantificação de 4,41×10-6 mol L-1 e 6,21×10-6 mol L-1, respectivamente. Além disso, a sensibilidade do eletrodo não modificado com nanotubos foi 0,01 µA per mmol L-1, consideravelmente menor que os valores de 5,34 e 6,97 µA per mmol L-1 obtidos usando nanotubos oxidados de carbono de parede múltipla (pequenos e longos), respectivamente.

1-Methyl-4-nitro-2-brominemethylimidazole (4-NimMeBr), was electrochemically reduced on mercury, glassy carbon and multiwalled carbon nanotubes (MWCNT) modified electrodes. 4-NimMeBr was adsorbed on the MWCNT modified electrode thus permitting the implementation of an adsorptive stripping voltammetric (ASV) method. We have used 4-NimMeBr as a prototype electroactive nitro compound to study the effect of both the size of the nanotubes and its functionalization by oxidation. The oxidized MWCNT forms better dispersions than the non-oxidized, producing electrode surface with higher density of MWCNT as was determined by electrochemical mapping using scanning electrochemical microscopy (SECM). Under the optimized conditions, the peak current was proportional to the concentration of 4-NimMeBr in the range of 10-6 mol L-1 to 10-4 mol L-1 with detection and quantification limits of 4.41×10-6 mol L-1 and 6.21×10-6 mol L-1, respectively. The sensibility of bare electrode was 0.01 µA per mmol L-1, which was lower than the value of 5.34 and 6.97 µA per mmol L-1 obtained using short and large oxidized MWCNT, respectively.