Copper nitroprusside was formed on aminopropylsilica silica gel (3-AS) surface (SiCuNP) previously prepared following two steps. These materials were thoroughly characterized by Infrared (FTIR) and cyclic voltammetry. The above techniques confirmed the successful formation of the copper nitroprusside on the silica surface. The cyclic voltammogram of CuNPSD were found to exhibit two redox couples with (Eθ,)1 = 0.34 V; (Eθ,)2 = 0.76 V vs. Ag/AgCl, KCl(sat) (KCl = 1.0 mol L-1; v = 20 mV s-1) attributed to the redox processes Cu(I)/Cu(II) and Fe(II)(CN)5NO/Fe(III)(CN)5NO respectively. The second redox process ((Eθ,)2 presented by the graphite paste electrode with SiCuNP shows electrocatalytic activity for the oxidation of N-acetylcysteine. The linear range for the determination of N-acetylcysteine was found between 9.9 × 10-5 and 8.9 × 10-4 mol L-1 showing a detection limit of 4.18 × 10-5 mol L-1 and an amperometric sensitivity of 3.02 × 10-2 A / mol-1 L. © 2011 by ESG.

The present work reports the development of a novel electrochemical sensor for the selective detection of fructose. The sensor was developed through electropolymerization of a molecularly imprinted polymer film on a reduced graphene oxide modified electrode. The modified electrode was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, atomic force microscopy and RAMAN spectroscopy. Through the application of the modified electrode, the recognition of fructose molecules occurred in a concentration range of 1.0 × 10−14 to 1.0 × 10−11 mol L−1, under a Langmuir adsorption isothermal model. The sensitivity and limits of detection and quantification obtained for the sensor were 9.9 × 107 A L mol−1, 3.2 × 10−15 mol L−1 and 1.1 × 10−14 mol L−1, respectively. The analytical method used for the detection of fructose presented good reproducibility, stability and accuracy, and was successfully applied for the quantification of this sugar in orange, apple and grape juices.

A novel nanostructured composite, azide copper octa (3-aminopropyl)octasilsesquioxane (ASCA) was incorporated into a graphite paste electrode and the electrochemical studies were conducted with cyclic voltammetry. The cyclic voltammogram of the modified graphite paste electrode with ASCA (GPE-ASCA), showed one redox couple with formal potential (Eθ) = 0.30 V and an irreversible process at 1.1 V (vs Ag/AgCl; NaCl 1.0 mol L-1; v = 20 mV s-1). The redox couple with (Eθ) = 0.30V presents an electrocatalytic response for determination of ascorbic acid. The modified electrode gives a linear range from 1.0×10-4 -1.0×10-3 mol L-1 (r = 0.998) for the determination of ascorbic acid with detection limit of 6.9×10-5 mol L-1 and standard deviation of 2.3% for n = 3. The amperometric sensitivity was 122.1 mA/mol L-1 for ascorbic acid. The application this electrode was tested and ascorbic acid in three commercial pharmaceutical product (Cebion, Cewin and Redoxon) have been determined. © 2011 by ESG.

This paper describes a voltammetric study of cadmium nitroprusside synthesized from different compositions of water/formamide in your reaction of Cd2+ with [FeIII(CN)5NO]2- (CdNP). After infrared and transmission electron microscopy characterization, the CdNP was incorporated into a carbon paste electrode and a systematic voltammetric study was performed for four systems (CdNP-1, CdNP-2, CdNP-3 and CdNP-4). The spectroscopic studies reveals that all preparations was conducted with success. The cyclic voltammogram of all CdNP particles obtained from a carbon paste electrode modified (10% m/m) exhibited a redox couple with formal potential (Eθ') = 0.63 ± 0.02 V (10 % (m/m); v=20 mV s-1; KNO3 1.0 M) attributed to the redox process [FeII(CN)5NO]/[FeIII(CN)5NO] in the presence of Cd2+.