Este trabalho apresenta a construção de um novo sensor eletroquímico para detecção de analitos orgânicos, usando um eletrodo de carbono vítreo (GCE) modificado com um filme de rutênio suportado em quitosana. O filme de rutênio suportado em quitosana foi obtido a partir da síntese do complexo mer-[RuCl3(dppb)(H2O)] como precursor de [1,4-bis(difenilfosfina)butano] (dppb), e quitosana (QT). A estrutura do filme de rutênio suportado em quitosana na superfície do eletrodo de carbono vítreo foi caracterizada por espectroscopia UV-Vis, ressonância paramagnética eletrônica (EPR), microscopia eletrônica de varredura (SEM), microscopia de força atômica (AFM), difração de raios X de pó (XRD) e espectroscopia de absorção atômica (AAS). Um eletrodo de carbono vítreo foi modificado com um filme formado pela evaporação de 5 µL de uma solução composta de 5 mg de composto de rutênio suportado em quitosana (RuQT), solubilizado em 10 mL de ácido acético 0,1 mol L-1. Este eletrodo modificado foi testado como sensor eletroquímico para detecção de citrato de sildenafil (Viagra® 50 mg) e acetaminofen (Tylenol®). A técnica utilizada para essas análises foi voltametria de pulso diferencial (DPV), em 0,1 mol L-1 de H2SO4 (pH 1,0) e 0,1 mol L-1 de CH3COOK (pH 6,5) como eletrólitos suporte. Todas as análises foram realizadas durante um mês utilizando-se o mesmo eletrodo, sendo lavado com bastante água entre as análises de um analito e de outro e mantendo-o em geladeira quando não utilizado. Este eletrodo mostrou-se estável durante o período utilizado mostrando a não degradação do filme e apresentou uma resposta linear no intervalo de concentração avaliado (1,25 × 10-5 a 4,99 × 10-4 mol L-1).

This work presents the construction of a novel electrochemical sensor for detection of organic analytes, using a glassy carbon electrode (GCE) modified with a chitosan-supported ruthenium film. The ruthenium-chitosan film was obtained starting from the mer-[RuCl3(dppb)(H2O)] complex as a [1,4-bis(diphenylphosphine)butane] (dppb) precursor, and chitosan (QT). The structure of the chitosan-supported ruthenium film on the surface of the glassy carbon electrode was characterized by UV-Vis spectroscopy, electron paramagnetic resonance (EPR), scanning electron microscopy (SEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD) and atomic absorption spectroscopy (AAS) techniques. The glassy carbon electrode was modified with a film formed from the evaporation of 5 µL of a solution composed of 5 mg chitosan-supported ruthenium (RuQT) in 10 mL of 0.1 mol L-1 acetic acid. The modified electrode was tested as a sensor for sildenafil citrate (Viagra® 50 mg) and acetaminophen (Tylenol®) detection. The technique utilized for these analyses was differential pulse voltammetry (DPV) in 0.1 mol L-1 H2SO4 (pH 1.0) and 0.1 mol L-1 CH3COOK (pH 6.5) as supporting electrolyte. All analyses were carried out during a month using the same electrode. The electrode was washed only with water in between the analyses, keeping it in the refrigerator when it was not in use. This electrode was stable during the period utilized showing no degradation and presenting a linear response over the evaluated concentration interval (1.25 × 10-5 to 4.99 × 10-4 mol L-1).

The purpose of this study was to analyze written arguments found within laboratory reports by undergraduate students in a practical inorganic chemistry course. The quality of students' argumentation was analyzed based on the argumentation model developed by Kelly and Takao. Students presented scientific arguments grounded in data and building toward theoretical assertions. This indicates that students have some understanding of the rhetorical power of data in their explanations. The findings of this study also support the idea that Kelly and Takao's model is effective in other disciplines and in other rhetorical tasks distinct from those originally analyzed by them in their domain of oceanography.

Nitric Oxide has been shown to be involved in many important biological functions. It serves as a vasodilator and a neurotransmitter in the brain and peripheral nervous system. It is also involved in the bacteria-killing process by macrophages. In this review we will discuss progress in nitric oxide chemistry and we will also attempt to explain its action in the cardiovascular, nervous and immune systems.

In coordination chemistry the study of geometrical isomerization and reactivity of specific isomers is a topic of major importance. The preparation of specific isomers often requires considerable complexity, and it is important to acquire a sense of what is involved in studying isomerism in laboratory. If it is difficult sometimes to prepare pure isomers, it is not easier to understand the mechanisms of isomerization reactions since studies on this subject have shown conflicting results and diferent interpretations on the same system have been reported in the literature. Although cis-trans isomerism in octahedral metal complexes is a common occurrence, there are relatively few studies reporting how these isomerizations occur. This paper gives an overview on cis-trans isomerization processes and identification of these species.