An environmentally friendly reflectometric method for ranitidine determination in pharmaceuticals and human urine

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

An Environmentally Friendly Reflectometric Method for Bumetanide Determination in Pharmaceuticals

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Spectroscopy properties and energy level location of Gd(2)O(2)S:Pr(3+),Ce(3+)

In this work we propose the study of the spectroscopy properties and the energy level location of Ce(3+) and Pr(3+) in Gd(2)O(2)S, along with the effects of Ce(4+) (Ce(2)O(2)S(2)) incorporation in Gd(2)O(2)S and Gd(2)O(2)S: Pr(3+) in order to understand the formation and position of the associated defects energy levels in relation to the band structure of Gd(2)O(2)S and Pr(3+) energy levels. Ce-, Pr(3+)-doped and Pr(3+), Ce-doped Gd(2)O(2)S were prepared by the sulfidization of a basic gadolinium carbonate with S(8) using H(2)/N(2) (3.0/97.0%) and air during the firing of the precursor. Samples were analyzed by X-ray diffraction in order to guarantee the formation of the Gd(2)O(2)S single phase. Diffuse reflectance spectroscopy and luminescent measurements (emission/excitation) were used to locate Ce(3+), Pr(3+) and defects energy levels in relation to the band structure of Gd(2)O(2)S. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Desenvolvimento de um método reflectométrico ambientalmente mais amigável para a determinação de metoclopramida em formulações farmacêuticas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

TiO2 films organofunctionalized with 2-aminothiazole ligand and adsorbed Pd(II) ions applied in the photocatalytic degradation of phenol in an aqueous medium

This paper describes the preparation of thin titanium films via sol-gel route and their subsequent chemical modification by anchoring with 2-aminothiazole ligand and Pd(II) ion sorption, aiming to maximize the photocatalytic activity. The material was characterized by diffuse reflectance infrared Fourier transform spectroscopy, ultraviolet and visible spectrometry, X-ray diffractometry, and scanning electronic microscopy. The amount of palladium adsorbed on the film's surface, determined by graphite furnace atomic absorption spectrometry, showed a value of 2.69 x 10(16) atoms CM-2. The photocatalytic tests indicated that the functionalization with 2-aminothiazole and the adsorption of palladium (II) were determinants in the semiconductor's enhanced photocatalytic activity. (c) 2007 Elsevier B.V. All rights reserved.

Densification and electrical conductivity of fast fired manganese-doped ceria ceramics

Reactive pure and manganese-doped (5% and 10 at.%) ceria nanosized powders were prepared by the polymeric precursor technique. Physical properties of powder materials were studied by X-ray diffraction, nitrogen adsorption, and diffuse reflectance infrared Fourier transform spectroscopy. Characterization of powder compacts after fast firing at 1200 degrees C for 5 min was carried out by scanning electron microscopy and impedance spectroscopy measurements. The bulk apparent density of sintered pellets was determined for pellets of different compositions sintered at 1200 degrees C. A gradual decrease of the particle size occurs with increasing doping content. Relatively high values of apparent density were obtained after fast firing doped specimens at 1200 degrees C. DRIFT spectra evidence that a fraction of Mn ions was segregated onto particles surface. The electrical resistivity of sintered pellets reveals different mechanisms of conduction depending on the Mn content. (C) 2005 Elsevier B.V All rights reserved.

Preparation and characterization of PAni-PMMA dispersions

Blends of polyaniline (PAni) and poly(methyl methacrylate) (PMMA) have been produced using core-shell particle synthesis, which is advantageous because it allows changing surface-related properties of PMMA with relatively small amounts of PAW and without the use of organic solvents. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements indicated that the deposition of pollyaniline seems to alter the regular shape of the primary acrylic latex particles. The coverage of PMMA particles by PAW was confirmed by FTIR measurements, where distinct data were obtained from the transmission and diffuse reflectance modes, since the latter is surface sensitive. The zeta potential, which is also a surface-related property, increased with the contents of PAW, as the shells probably became protonated with PAW in the emeraldine salt form. Coverage with PAW did not affect the thermal bulk properties of the PMMA shells.

Physical properties of silicate glasses doped with SnO2

The presence of tin in the network of silicate glasses produces changes in several of their physico-chemical properties. Glasses with the composition (mol%) 22Na(2)O (.) 8CaO (.) 70SiO(2) containing up to 5 wt% of SnO2 were analyzed under several experimental techniques. Dilatometric measurements showed an increase of the glass transition temperature with increasing tin content, while the average thermal expansion coefficient is reduced. Vickers microhardness, density, and refractive index also increase with the tin content. Diffuse reflectance spectra in the infrared (DRIFT) showed that the presence of tin, even at low concentrations, is responsible for some structural changes since there is an increase of the bridging oxygen concentration. The doped glasses present a brown color and optical absorption spectra measurements are interpreted as being due to precipitation of tin in the form of colloidal particles during cooling of the melted glass. In the Na+ <-> K+ ion exchange process the presence of tin in the glass network hinders the diffusion of these ions. The diffusion coefficients of those ions were calculated by the Boltzmann-Matano technique, after concentration profiles obtained by EDS measurements. All results obtained present evidences that Sn4+ cation acts as a glass network former. (c) 2005 Elsevier B.V. All rights reserved.

Alumina/zirconia composite coated by biomimetic method

In this study, a bioactive zirconia-toughened alumina (ZTA) composite was developed for orthopedic applications. This composite was obtained by slip casting of suspension powder mixtures.Biomimetic processes were used to grow a bone-like apatite layer on composite substrates using sodium silicate solution as a nucleating agent and simulated body fluids. The composites, with or without coating, were characterized by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and scanning electron microscopy (SEM) with energy dispersion spectroscopy (EDS), and their apparent density was determined by the Archimedes method. The composites obtained by this process possessed the expected stiffness and dimensions and their density values were similar to those of the composite's theoretical density (98.8%TD). The morphology of the hydroxyapatite formed on the composite surface was homogeneous and composed of small globules, characterizing a carbonated hydroxyapatite. The results of the tests indicated that the method employed to produce the composite and its coating was efficient under the conditions of this study. (c) 2006 Elsevier B.V. All rights reserved.

Influence of different solvents on the structural, optical and morphological properties of CdS nanoparticles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Synthesis, characterization, crystal structure, and biological studies of vanadium complexes with glycolic acid

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influence of pH on the incorporation and growth of Pb2CrO5 crystallites in silica matrix

Pb2CrO5 nanoparticles were embedded in an amorphous SiO2 matrix by the sol-gel process. The pH and heat treatment effects were evaluated in terms of structural, microstructural and optical properties from Pb2CrO5/SiO2 compounds. X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS), and diffuse reflectance techniques were employed. Kubelka-Munk theory was used to calculate diffuse reflectance spectra that were compared to the experimental results. Finally, colorimetric coordinates of the Pb2CrO5/SiO2 compounds were shown and discussed. In general, an acid pH initially dissolves Pb2CrO5 nanoparticles and following heat treatment at 600 A degrees C crystallized into PbCrO4 composition with grain size around 6 nm in SiO2 matrix. No Pb2CrO5 solubilization was observed for basic pH. These nanoparticles were incorporated in silica matrix showing a variety of color ranging from yellow to orange.

Dental implants: Surface modification of cp-Ti using plasma spraying and the deposition of hydroxyapatite

The commercial pure titanium (cp-Ti) is currently being used with great success in dental implants. In this work we investigate how the cp-Ti implants can be improved by modifying the metal surface morphology, on which a synthetic material with properties similar to that of the inorganic part of the bone, is deposited to facilitate the bone/implant bonding. This synthetic material is the hydroxyapatite, HA, a calcium-phosphate ceramic. The surface modification consists in the application of a titanium oxide (TiO2) layer, using the thermal aspersion - plasma spray technique, with posterior deposition of HA, using the biomimetic method. The X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX) and Diffuse Reflectance Infrared Fourier Transform (DRIFT) techniques have been used for characterizing phases, microstructures and morphologies of the coatings. The TiO2 deposit shows a mixture of anatase, rutilo and TiO2-x phases, and a porous and laminar morphology, which facilitate the HA deposition. After the thermal treatment, the previously amorphous structured HA coating, shows a porous homogeneous morphology with particle size of about 2-2.5 μm, with crystallinity and composition similar to that of the biological HA.

A simplified reflectometric method for the rapid determination of dipyrone in pharmaceutical formulations

This paper describes a simple, portable and environmentally friendly method for the rapid determination of dipyrone in pharmaceuticals by using diffuse reflectance spectroscopy. The proposed method is based on the reflectance measurements of the orange compound produced from the spot test reaction between dipyrone and p-dimethylaminocinnamaldehyde (p-DAC), in acid medium, using a filter paper as solid support. Experimental design methodologies were used to optimize the measurement conditions. All reflectance measurements were carried out at 510 nm and the linear range was from 1.42 × 10-4-2.85 × 10-3 mol L-1, with a correlation coefficient of 0.999. The limit of detection (LOD) and the limit of quantification (LOQ) were 1.20 × 10-5 mol L-1 and 4.00 × 10-5 mol L-1, respectively. The intraday precision and interday precision were studied for 10 replicate analyses of 7.90 × 10-4 mol L-1 dipyrone solution. The coefficients of variation were 1.1 and 0.9%, respectively. The proposed method was applied successfully to the determination of dipyrone in commercial brands of pharmaceuticals. No interferences were observed from the common excipients in formulations. The results obtained by the proposed method were favorably compared with those given by the Brazilian Pharmacopoeia procedure at 95% confidence level. ©2007 Sociedade Brasileira de Química.

A simple and environmentally friendly reflectometric method for the rapid quantitative analysis of captopril in pharmaceutical formulations

This paper describes a simple, environmentally friendly and rapid quantitative spot test procedure for the determination of captopril (CPT) in bulk drug and in pharmaceutical formulations by using diffuse reflectance spectroscopy. The proposed method is based on the reflectance measurements of the orange compound (λ max 490 nm) produced by the spot test reaction between CPT and p-chloranil (CL). Under optimal conditions, calibration curves were obtained for CPT by plotting the optical density of the reflectance signal (A R) vs. the log of the mol L -1 concentration, from 6.91×10 -3 to 1.17×10 -1, with a good coefficient of determination (R 2 = 0.9992). The common excipients used as additives in pharmaceuticals do not interfere in the proposed method. The method was applied to determine CPT in commercial pharmaceutical formulations. The results obtained by the proposed method are compared favorably with those obtained by an official procedure at 95% confidence level. The method validation results showed that the sensitivity and selectivity of the methods were adequated for drug monitoring in industrial quality control laboratories. © 2011 Moment Publication.