506 resultados para CROMATOGRAFIA

em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"


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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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Since the introduction of GC there has been an ongoing interest in reducing time of analysis resulting in new terms and definitions such as ultra fast gas chromatography (UF-GC). One of the most used definitions describes UF-GC as a technique that combines the employment of short narrow bore column with very fast temperature programming rates producing chromatographic peaks in the range of 50 ms and allowing separations times in 1-2 min or less. This paper summarizes the analytical approaches, the main parameters involved and the instrumentation towards UF-GC.

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The interference practised by the products in degradation of paracetemol when there is the application of spectrophotometry UV is the main obstruction to the execution of studies of thermic stability. The application of chromatography in slender layer to the isolation of paracetamol, besides being the excessively hard to apply was satisfactory to the desired proposal. The type and extension of degradation suffered by paracetamol in solution suggest the convenient inclusion, in the formulations, of one system antioxidant. This practice makes possible the blockage of the oxidation of p-aminophenol, produced by the hydrolytic degradation of paracetamol; this fact propitiated the diminution of the number of products of degradation in the medicine, making the use more secure. On the other hand, considering especially the methodological necessities of the present work, the presence of one antioxidant system facilitated the separation of paracetamol through the Thin Layer Chromatography and consequently optimized its quantification by Spectrophotometry UV during the study of thermic stability. The formulation proposed revealed excellent stability.

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This work reports the separation of phenolic compounds present in the metabolic extract of the lichen Neuropogon aurantiaco-ater (Usniaceae). The crude extract was fractionated by droplet counter-current chromatography using a solvent mixture of high polarity (chloroform:methanol:water at 43:37:20, in ascending mode). The separation resulted in the isolation of usnic and protocetratic acid, which were identified by TLC, HPLC, and NMR tests.

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A rapid, sensitive and reliable thin-layer chromatography/spectrophotometry screening procedure was developed for quantitative determination of diuretics associated in pharmaceutical dosage forms. The chromatographic method employed microcrystalline cellulose and butanol : acetic acid : water (4:1:1) or amilic alcohol : ammonium hydroxide 25% (9:1) as mobile phases and detection by U.V. light. The drugs were extracted using a simple procedure and were quantified by U.V. spectrophotometry. Results varied from 97.5 to 102.5% and are similar to those obtained by conventional methods. This method of quantification of diuretics is promising for quality control of drugs.

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