972 resultados para colorimetric


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

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

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Os autores estudaram o comportamento cromatográfico de preparações farmacêuticas comerciais contendo o íon Fe (II). Utilizando celulose microcristalina/Propanol: ácido clorídrico 4 N: ácido acético concentrado: ácido nítrico concentrado: clorofórmio (40: 5: 5: 10: 10), como sistema cromatográfico e alizarina como reagente de detecção, Fe (II), Mn (II), Mg (II), Cu (II), Zn (II) e Ca (II) foram separados e identificados pela Cromatografia Planar. O Fe (II) foi determinado pela reação com a ortofenantrolina, resultando em solução adequada para quantificação colorimétrica.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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

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

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Avaliaram-se a concentração de lactato e a glicemia em sete cadelas em trabalho de parto submetidas à cesariana e em seus respectivos neonatos. O lactato materno foi mensurado utilizando-se medidor portátil e pelo método enzimático colorimétrico. Nos neonatos avaliou-se também o peso ao nascimento. Os valores de lactato materno e neonatal foram estatisticamente diferentes, sendo mais elevado nos neonatos. Ao nascimento, as cadelas e os neonatos encontravam-se normoglicêmicos, e não se observou correlação entre a glicemia de ambos. Os valores de lactato obtidos pelo o analisador portátil (3,5±0,6mmol/L) foram mais altos do que os obtidos pelo método enzimático colorimétrico (1,6±0,6mmol/L). Observou-se correlação significativa entre o peso do neonato e a concentração de lactato, isto é, os filhotes de menor peso apresentaram maior concentração de lactato.

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Droplets formed at the tip of a tube under the same conditions possess extreme uniformity of form, volume and weight. These properties of liquid drop formation have been known for a long time and consequently many applications for the drop have been found in instrumentation and chemical analysis methods. In the present paper, we report on the analytical use of a dynamic LED-based flow-through optical absorption detector with optical path length controlled by continuous dropping of a solution. This arrangement consists of a flow cell built within a high-intensity red LED (lambda (max)=630 nm). The feasibility of the detector is demonstrated by colorimetric determination of methylene blue, and ammonium by Berthelot's reaction, in a flow-injection system. For ammonium, the reaction forms a blue dye (indophenol) with a maximum absorption at 630-650 nm. The detection limit, considered as 3 times the signal of the blank, is better than 125 mu g l(-1). The small flow cell represents a good combination of optical path length, low volume and fast washout. This detector can be used advantageously in automated methods and can represent a solution to problems of optical detection involving gas bubbles and precipitation of particles in turbidimetric applications.

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A new palladium(II) complex with methionine sulfoxide was synthesized and characterized by a set of chemical and spectroscopic techniques. Elemental and mass spectrometry analyses of the solid complex fit to the composition [Pd(C5H10NO3S)(2)]center dot H2O. C-13 NMR, [H-1-N-15] NMR and infrared spectra indicate coordination of the amino acid to Pd(II) through the carboxylate and amino groups in a square planar geometry. The complex is soluble in water.Biological activity was evaluated by cytotoxic analysis using HeLa cells. Determination of cell death was assessed using a tetrazolium salt colorimetric assay, which reflects the cells viability. After incubation for 48 h, 20% of cell death was achieved at a concentration of 200 mu mol L-1 of the complex. (c) 2006 Elsevier B.V. All rights reserved.

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An amperometric biosensor for salicylate detection was developed by immobilizing salicylate hydroxylase via glutaraldehyde onto a polypyrrole film doped with hexacyanoferrate, supported on a glassy carbon electrode surface. The sensor monitors the catechol produced in the enzymatic reaction on the film surface, at an applied potential of 150 mV vs. SCE. A [NADH]/[salicylate] ratio between 2 and 4 gave the best response. The biosensor presented the best performance in a solution with pH=7.4. The response time was about 40 s. A linear range of response was observed for salicylate concentrations between 1.0x10(-5) and 1.0x10(-4) mol l(-1) and the equation adjusted for this curve was I=(-0.04+/-0.01)+(11.4+/-0.2)[salicylate] with a correlation coefficient of 0.999 for n=6. The biosensor retains its activity for at least 10 days despite daily use. The results obtained using the biosensor for salicylate determination, in three different samples of antithermic drugs, presented a good correlation with the standard colorimetric method.

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Starches from six different species (cassava, arrowroot, sweet potato, yam, canna and ginger) were isolated and some structural and physicochemical characteristics analysed and correlated. Phosphorous and amylose contents were determined using a colorimetric method and measuring iodine affinity, respectively. Molecular weight distributions of starches were analysed by Sepharose CL 2B. Granular shape and size distribution were performed using an image analyser system attached to a light microscope. Swelling power was determined at 60, 70, 80 and 90 degrees C. Pasting and thermal properties were measured using a rapid viscoanalyser, and a differential scanning calorimeter, respectively. Phosphorous content varied from 0.007 to 0.031% for cassava and canna starches, respectively. Yam, canna and ginger starches displayed higher amylose contents (32.6, 31.7 and 26.5%, respectively) than cassava, arrowroot and sweet potato starches (19.8, 20.8 and 22.6%, respectively). These last three starches displayed amylose molecules of higher molecular weight than those shown for yam, canna and ginger starches. Canna starch showed higher proportions of longer branch chains of amylopectin than others starches. The size and shape of granules were quite variable among all starches and the average size of granules varied from 13.9 to 42.3 mu m for sweet potato and canna, respectively. Swelling power, pasting, and thermal properties were affected by structural characteristics of the starches.

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The authors have studied the chromatographic behavior of parenteral preparations for pediatric use containing inorganic cations. After separation and identification by thin-layer chromatography, Mn2+, Zn2+, and Cu2+ were analyzed by a method based on reaction with an appropriate reagent and extraction with an organic solvent which yielded elution and preconcentration, resulting in an appropriate solution for colorimetric quantitation. Cr3+ cation was determined by atomic absorption spectrophotometry after appropriate chromatographic separation, using microcrystalline cellulose (adsorbent) and an acetone:water:hydrochloric acid mixture (80:5:8) as the mobile phase.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Lactate is a compound produced by the anaerobic metabolism of glucose, and hyperlactataemia occurs when the rate of production of lactate exceeds the rate of elimination. This occurs in situations of hypoxia and tissue hypoperfusion. Lactate has been considered a useful prognostic indicator in critically ill patients. Pyometra is a disease of adult female dogs characterized by inflammation of the uterus with an accumulation of exudate, which occurs during the luteal phase. It is one of the most common diseases that occur in the genital tract of female dogs. A total of 31 dogs were diagnosed with pyometra. The diagnosis was confirmed at ultrasonography. of the 31 dogs, 25 females had open cervix pyometra and six had closed cervix pyometra. Plasma lactate concentrations were determined by an enzymatic colorimetric method. The average concentration (+/- SD) of plasma lactate in all 31 bitches with pyometra was 3.55 +/- 0.46 mm. Healthy dogs had plasma lactate concentrations between 0.3 and 2.5 mm (mean +/- SD). Concentrations ranged from 0.8 to 2.9 mm when plasma lactate was measured with a portable device and 0.42.6 mm with the blood gas analyser. Even though plasma lactate values vary between several studies and equipment used to measure concentrations, our results for dogs with pyometra are higher indicating hyperlactataemia (Thorneloe et al. , Can Vet J 48, 283288). Plasma lactate in dogs with closed cervix pyometra was mean +/- SD and in dogs with open cervix pyometra, it was mean +/- SD. The plasma lactate concentration in dogs with pyometra was higher than in healthy bitches, and there was no influence of patency of the cervix on the concentration of plasma lactate concentrations. Plasma lactate concentrations were similar for animals with open and closed pyometra (3.54 +/- 0.52 to 3.64 +/- 1.03 mm).