The chloropropyl silica gel was modified with octa(3-aminopropyl) octasilsesquioxane and characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), spectroscopies, and surface and area porosity. The specific sorption capacity of metallic ions (Cu2+ and Ni2+) increases in the following solvent order: water < ethanol 42% < ethanol < ketone. The high values of the constant (K) in the order of 103 L mol-1 suggested the high adsorbent capacity of the modified silica (SGAPC) for Cu2+ and Ni2+. SGAPC was applied to a separation column and shows recoveries of around 100% of copper in samples of sugar cane spirit, vodka, ginger brandy, and ethanol fuel. © 2013 Devaney Ribeiro Do Carmo et al.

Octa-(3-chloropropyl) octasilsesquioxane (SS) was functionalized with a PAMAM dendrimer (SP) and characterized by some spectroscopic techniques such as Fourier Transform Infrared, Nuclear Magnetic Resonance, X-ray diffraction, X-ray Dispersive Energy Spectroscopy, Scanning Electron Microscopy and cyclic voltammetry. As a fast application, after there the Ag+ was adsorbed by SP and in a second step, the resulting material was reacted with potassium hexacyanoferrate (III) (AgHSP). The cyclic voltammogram of the AgHSP showed two redox pairs with formal potentials (Eθ’) of Eθ’ (I) = 0.26 V and Eθ’ (II) = 0.71 V (v = 20 mV s−1, KNO3 1.00 mol L−1, pH 7.00) assigned to processes Ag0 / AgI and FeII (CN)6 / FeIII (CN)6, respectively. The analytical application of this new material (AgHSP) was tested in the rapid detection of acid ascorbic by strong electrocatalysis using graphite paste electrode (GPE). The limit of detection (LOD) obtained for this system was 7.034 × 10−5 mol L−1 with an excellent amperometric sensitivity of 0.0835 A / mol L−1.

Titanium (IV) silsesquioxane was occluded in the cavities of a mesoporous silica MCM-41. The material was chemically modified with nickel hexacyanoferrate (III) (named MTTiPNiH) and subsequently characterized by spectroscopic techniques: Fourier Transform Infrared, X-ray Dispersive Energy Spectroscopy, Scanning Electron Microscopy and cyclic voltammetry. The voltammetric studies of MTTiPNiH was obtained using a graphite paste electrode which was possible to observe one well-defined redox pair with formal potential E°′ = +0.53 V attributed to FeII(CN)6 / FeIII(CN)6 in the presence of Ni2+ ions. As an application, the graphite paste electrode modified with MTTiPNiH was tested for sulphite and dipyrone detection.

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.

A zinc-modified octa(aminopropyl)silsesquioxane and the cyan compound Na2[Fe(CN)5NO] were prepared to create a hybrid electroactive material (ACZnN) characterized employing the spectroscopic techniques Raman spectroscopy, Diffuse Reflectance (DR), X-Ray diffraction (XRD), Scanning Electronic Microscopy (SEM), thermogravimetric analysis (TGA) and voltammetric measurements. The cyclic voltammetry technique indicated the solid ACZnN on the electrode surface as presenting two redox processes, with EIθ' = 0.21 V and EIIθ' = 0.51 V (vs Ag/AgCl(sat)) attributed to the redox pair Fe2+(CN)5NO/ Fe3+(CN)5NO in the absence and presence of Zn2+, respectively, as well as adequate stability, reliability and efficiency for practical applications. The ACZnN-modified graphite paste electrode exhibited a sensitive and catalytic oxidation response towards N-acetylcysteine and was successfully employed 1in the catalytic electro-oxidation of N-acetylcysteine employing differential pulse voltammetry techniques. The lowest limit of detection and best amperometric sensitivity obtained by differential pulse voltammetry were 0.657 µmol L−1 and 500 mA/mol L−1, respectively, from 1.0 × 10–6 to 1.0 × 10–5 M. Further analyses applying this method also demonstrated the compound’s efficiency in detecting N-acetylcysteine in synthetic urine samples.

Octa(3-aminopropyl)octasilsesquioxane and DAB-AM-16 dendrimer, due to their specific chemical and physical properties, give wide application in various fields of science. Because they have a large number of NH2 reactive groups at their ends, they are capable of interacting with different substances, generating in this way different compounds with enormous analytical potential that can be used in the electrocatalytic determinations and oxidations of some substances of environmental and biological interest. In this work, after a rigorous voltammetric study, the electroanalytical potentiality of the chemically Ni2+ metal ions chealed silica gel surface modified with octa(3-aminopropyl)octasilsesquioxane and DAB-AM-16 dendrimer was tested for dipyrone detection. The cyclic voltammogram of the graphite paste electrode, with both materials (20% w/w) showed two redox process. The following formal potential (Eθ′) values for both materials were identical: (Eθ′)I = 0,26 V; (Eθ′)II = 0,51 V vs Ag/AgCl (KCl = 1.0 mol L−1; v = 20 mV s−1). For dipyrone detection assay, the limite of detection were of 9.17 × 10−5 mol L−1 with an amperometric sensitivity of 15.78 mA / mol L−1 with a relative standard deviation of ±3% (n = 3) and of 4.79 × 10−4 mol L−1 with an amperometric sensitivity of 11.10 mA / mol L−1 with a relative standard deviation of ±2% (n = 3) respectively for silica gel surface modified with octa(3-aminopropyl)octasilsesquioxane and DAB-AM-16 dendrimer.

A composite prepared from titanium (IV) silsesquioxane and phosphoric acid (TTiP) was prepared and occluded into the H-FAU zeolite (ZTTiP). The material was chemically modified with nickel and subsequently by potassium hexacyanoferrate (III) (ZTTiPNiH). It was preliminarily characterized by infrared spectroscopy (IR), energy dispersive X-ray spectroscopy (EDS) and cyclic voltammetry (CV). The voltammetric behavior of ZTTipNiH was obtained employing a modified graphite paste electrode (GPE) showing one well-defined redox couple with a formal potential of E(Formula presented.) 0.51V (vs Ag/AgCl(sat)), KCl (3M) (20% w/w; v = 20 mV s− 1; KCl; 1.00 mol L− 1) corresponding to the NiIIFeII(CN)6/NiIIFeIII(CN)6 redox process. After rigorous voltammetric studies, the GPE modified with ZTTiPNiH was applied for facile and rapid detection of sulfite. From the analytical curve, a linear response was obtained in a concentration range of 0.05 to 0.80 mmol L− 1 and a detection limit (3σ) of 0.05 mmol L− 1 with a relative standard deviation of 4.21% (n = 3) and an amperometric sensitivity of 14.42 mA L mol− 1 for sulfite.