937 resultados para HPLC-UV-PAD


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A statistical mixture-design technique was used to study the effects of different solvents and their mixtures on the yield, total polyphenol content, and antioxidant capacity of the crude extracts from the bark of Schinus terebinthifolius Raddi (Anacardiaceae). The experimental results and their response-surface models showed that ternary mixtures with equal portions of all the three solvents (water, ethanol and acetone) were better than the binary mixtures in generating crude extracts with the highest yield (22.04 ± 0.48%), total polyphenol content (29.39 ± 0.39%), and antioxidant capacity (6.38 ± 0.21). An analytical method was developed and validated for the determination of total polyphenols in the extracts. Optimal conditions for the various parameters in this analytical method, namely, the time for the chromophoric reaction to stabilize, wavelength of the absorption maxima to be monitored, the reference standard and the concentration of sodium carbonate were determined to be 5 min, 780 nm, pyrogallol, and 14.06% w v-1, respectively. UV-Vis spectrophotometric monitoring of the reaction under these conditions proved the method to be linear, specific, precise, accurate, reproducible, robust, and easy to perform.

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Polygala cyparissias is a plant widespread in Southern Latin America. Recently, we demonstrated the gastroprotective activity of the extract, as well as for one of the isolated metabolites-1,7-dihydroxy-2,3-methylenedioxyxanthone (MDX). In this study, a HPLC method for the quantification of MDX was validated. The HPLC method was linear (0.5-24 µg mL-1 of MDX) with good accuracy, precision and robustness. The content of MDX in the extracts from whole and different parts of the plant ranged from 0 to 5.4 mg g-1 and the gastroprotective index ranged from 72.1 to 99.1%. Thus, the method might be used for the standardization of the extracts based on the MDX marker.

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A stability-indicating RP-HPLC method is presented for determination of gatifloxacin and flurbiprofen in binary combination. Gatifloxacin, flurbiprofen and their degradation products were detected at 254 nm using a BDS Hypersil C8 (250 X 4.6 mm, 5 µm) column and mixture of 20 mM phosphate buffer (pH 3.0) and methanol 30:70 v/v as mobile phase. Response was linear over the range of 15-105 mg mL-1 for gatifloxacin (r² > 0.998) and of 1.5-10.5 mg mL-1 for flurbiprofen (r² > 0.999). The developed method efficiently separated the analytical peaks from degradation products (peak purity index > 0.9999). The method developed can be applied successfully for determination of gatifloxacin and flurbiprofen in human serum, urine, pharmaceutical formulations, and their stability studies.

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RP-HPLC based analytical method for use in both quality control of green tea in a semisolid formulation and for in vitro drug release assays was developed and validated. The method was precise (CV < 5%), accurate (recovery between 98% and 102%), linear (R² > 0.99), robust, and specific for the determination of epigallocatechin 3-gallate (EGCG), caffeine (CAF), and gallic acid (GA). In a diffusion cell chamber, the release rate of EGCG was 8896.01 µg cm-2. This data showed that EGCG will be able to exert its systemic activity when delivered though the transdermal formulation, due to its good flux rates with the synthetic membrane.

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Octocrylene (2-ethylhexyl 2-cyano-3,3-diphenyl-2-propenoate) is present in several sunscreens and is known to work synergistically with UV filters. We prepared eight octocrylene-related compounds to test their photoprotective activities by measuring diffuse transmittance. The compounds had varied photoprotection profiles, with Sun Protection Factors (SPF) ranging from 1 to 5 and UVA Protection Factors (UVAPF) ranging from 1 to 8. Compounds 4, 5, and 7 showed the best protection against UVB sunrays, while compounds 5, 6, and 7 presented the best results for protection from UVA, so compound 7 had the most balanced protection overall. Results for compounds 4, 8, and 9 are reported for the first time in the literature.

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This article describes the isolation and identification of flavonoids in the hydroethanolic extract of the aerial parts from Tonina fluviatilis and evaluation of their antiradical activity. A method based on HPLC-DAD was developed and validated for detecting and quantifying flavonoids in hydroethanolic extracts. The flavonoids identified and quantified in the extract were 6,7-dimethoxyquercetin-3-O-β-D-glucopyranoside (1), 6-hydroxy-7-methoxyquercetin-3-O-β-D-glucopyranoside (2), and 6-methoxyquercetin-3-O-β-D-glucopyranoside (3). The developed method presented good validation parameters, showing that the results obtained are consistent and can be used in ensuring the quantification of these constituents in the extracts. Compounds 2 and 3 showed strong antiradical activity when compared with the positive controls (quercetin and gallic acid).

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In this work, a spectrophotometric methodology was applied in order to determine epinephrine (EP), uric acid (UA), and acetaminophen (AC) in pharmaceutical formulations and spiked human serum, plasma, and urine by using a multivariate approach. Multivariate calibration methods such as partial least squares (PLS) methods and its derivates were used to obtain a model for simultaneous determination of EP, UA and AC with good figures of merit and mixture design was in the range of 1.8 - 35.3, 1.7 - 16.8, and 1.5 - 12.1 µg mL-1. The 2nd derivate PLS showed recoveries of 95.3 - 103.3, 93.3 - 104.0, and 94.0 - 105.5 µg mL-1 for EP, UA, and AC, respectively.

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Este trabalho teve por objetivo avaliar o efeito da irradiação UV-C no controle in vitro de Monilinia fructicola e Rhizopus stolonifer e no controle das doenças causadas por estes fungos em pêssegos inoculados com ferimento. No experimento in vitro, avaliou-se o crescimento micelial dos fungos em meio BDA após a exposição nas doses de UV-C de 0, 0,26, 0,52, 1,04, 3,13, 5,22, 10,44, 15,66, e 31,32 kJ.m-2 num equipamento com quatro lâmpadas com taxa de fluência de 1,74 mW.cm-2. Nos experimentos in vivo, os frutos foram tratados com irradiação UV-C de forma protetora e curativa. No tratamento protetor, os frutos foram expostos a 1,04 kJ.m-2 por 1 min. e foram inoculados imediatamente após e 16, 24 e 40 h após. No tratamento curativo, os frutos foram inoculados, incubados e irradiados com doses de UV-C de 0, 1,04, 5,22, 10,44, 15,66 e 31,32 kJ.m². Avaliou-se a incidência das doenças e a severidade da podridão parda. No experimento in vitro, apenas as doses aplicadas durante 1 e 10 min. de exposição reduziram o crescimento micelial de M. fructicola enquanto que a aplicação da luz UV-C entre 10-15 minutos reduziu o crescimento micelial de R. stolonifer e a dose aplicada durante 30 minutos inibiu completamente o crescimento micelial deste fungo. Não houve efeito protetor da luz UV-C no controle das doenças. Não houve controle curativo da podridão parda. A irradiação UV-C foi eficiente no controle curativo da podridão mole e o tempo de exposição de 10 min. foi o que apresentou melhor resultado.

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Diplomityö tehtiin Kidex Oy:lle, joka on Kiteellä sijaitseva Martela-konsernin tytäryhtiö. Kidex Oy toimii sopimusvalmistajana Martelalle sekä muille valituille levykalusteasiakkaille, ja tuotteet ovat pääasiassa toimisto- ja keittiökalusteita. Kevättalvella 2008 yritykseen siirrettiin Nummelasta pintakäsittelyosasto, jolla on tehty petsaus- ja lakkaustöitä. Näiden lisäksi tehtaalla on pohdittu mahdollisuuksia maalaustöihin, jotta UV-telalinjan kapasiteetti saataisiin paremmin käyttöön Työssä selvitettiin, mitä muutoksia UV-kovettuvilla aineilla maalaaminen vaatii linjaan ja luotiin edellytykset maalaustoiminnan aloittamiselle. Muutokset pyrittiin pitämään niin vähäisinä kuin mahdollista. Lisäksi määritettiin maalattavien tuotteiden laadun kriteerit ja todennusmenetelmät, jotka voidaan viestiä asiakkaille väärinkäsitysten välttämiseksi. Laadun todentamista varten valmistettiin sarja koekappaleita, joista mitattiin asiakkaan kannalta tärkeimmät maalikalvon ominaisuudet. Työssä tarkasteltiin myös pintakäsittelylaitoksia koskevaa VOC-asetusta ja verrattiin liuottimien kulutusta asetuksen määrittämiin rajoihin. Puulevystä valmistettujen kalusteosien pintakäsittely UV-telalinjalla eroaa oleellisesti perinteisistä menetelmistä esimerkiksi tuotantonopeuden osalta, joka johtuu pääasiassa pinnoitekalvon hetkessä tapahtuvasta kovettumisesta UV-valon vaikutuksesta. UV-aineet ovat käytännössä täysin kiinteistä aineista koostuvia, eivätkä näin sisällä vaarallisia haihtuvia liuottimia. UV-kovettuvilla tuotteilla maalaaminen on viime vuosina runsaasti tutkittu alue, joka eroaa tietyiltä osin myös pintakäsittelystä UV-kirkaslakoilla. Pigmentoitujen kalvojen kovettuminen vaatii erilaista UV-säteilyä ja levitysmäärien seuranta on huomattavasti tarkempaa.

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A técnica de CLAE com detecção UV-Vis foi empregada na análise do teor de cocaína em amostras apreendidas de cocaína e crack. Uma fase móvel de acetonitrila/água (95:5v/v) possibilitou um sinal de pico para a cocaína em 3,5 minutos. O sinal espectrofotométrico otimizado foi obtido em um comprimento de onda de 224 nm. A curva analítica de 1,0 a 40,0 ppm para cocaína foi obtida, exibindo um coeficiente de correlação linear de 0,9989, com limites de detecção e quantificação de 0,75 e 3,78 ppm, respectivamente. Esta metodologia foi aplicada na dosagem de amostras confiscadas de cocaína e crack no Laboratório de Polícia Científica de Ribeirão Preto-SP.

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This MSc work was done in the project of BIOMECON financed by Tekes. The prime target of the research was, to develop methods for separation and determination of carbohydrates (sugars), sugar acids and alcohols, and some other organic acids in hydrolyzed pulp samples by capillary electrophoresis (CE) using UV detection. Aspen, spruce, and birch pulps are commonly used for production of papers in Finland. Feedstock components in pulp predominantly consist of carbohydrates, organic acids, lignin, extractives, and proteins. Here in this study, pulps have been hydrolyzed in analytical chemistry laboratories of UPM Company and Lappeenranta University in order to convert them into sugars, acids, alcohols, and organic acids. Foremost objective of this study was to quantify and identify the main and by-products in the pulp samples. For the method development and optimization, increased precision in capillary electrophoresis was accomplished by calculating calibration data of 16 analytes such as D-(-)-fructose, D(+)-xylose, D(+)-mannose, D(+)-cellobiose, D-(+)-glucose, D-(+)-raffinose, D(-)-mannitol, sorbitol, rhamnose, sucrose, xylitol, galactose, maltose, arabinose, ribose, and, α-lactose monohydratesugars and 16 organic acids such as D-glucuronic, oxalic, acetic, propionic, formic, glycolic, malonic, maleic, citric, L-glutamic, tartaric, succinic, adipic, ascorbic, galacturonic, and glyoxylic acid. In carbohydrate and polyalcohol analyses, the experiments with CE coupled to direct UV detection and positive separation polarity was performed in 36 mM disodium hydrogen phosphate electrolyte solution. For acid analyses, CE coupled indirect UV detection, using negative polarity, and electrolyte solution made of 2,3 pyridinedicarboxylic acid, Ca2+ salt, Mg2+ salts, and myristyltrimethylammonium hydroxide in water was used. Under optimized conditions, limits of detection, relative standard deviations and correlation coefficients of each compound were measured. The optimized conditions were used for the identification and quantification of carbohydrates and acids produced by hydrolyses of pulp. The concentrations of the analytes varied between 1 mg – 0.138 g in liter hydrolysate.

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As doenças de pós-colheita são, em geral, de difícil controle e são responsáveis por perdas significativas de manga (Mangifera indica L.) e melão (Cucumis melo L.) no Brasil. Os principais patógenos pós-colheita do melão são Alternaria alternata, Fusarium pallidoroseum e Myrothecium roridum, enquanto que na manga são Colletotrichum gloeosporioides e Lasiodiplodia theobromae. O objetivo deste trabalho foi avaliar a sensibilidade dos propágulos destes patógenos aos tratamentos de hidrotermia e de radiação UV-C. Suspensões de conídios e discos de micélio de cada patógeno foram submetidos aos tratamentos de hidrotermia a 50, 55 e 58 ºC por 15 e 30 s e de radiação UV-C nas doses de 0,330 kJ m-2, 0,660 kJ m-2 e 1,320 kJ m-2. Após os tratamentos e incubação por 72 e 48 h, foram avaliados o número de unidades formadoras de colônias (UFCs) e o crescimento micelial dos patógenos, respectivamente. Os tratamentos apresentaram eficiência distinta entre os propágulos e os patógenos. O controle de UFCs e do crescimento micelial de C. gloeosporioides e L. theobromae foi superior a 88 % com água aquecida a 55 ºC ou 58 ºC, independente do tempo de tratamento. Para os mesmos patógenos, a maior dose de radiação, 1,320 kJ m-2, controlou acima de 96 % das UFCs. Entretanto, o controle do crescimento micelial destes patógenos com radiação UV-C foi inferior quando comparado ao uso de água aquecida a 55 ºC ou 58 ºC. O controle de UFCs de A. alternata, M. roridum e F. pallidoroseum foi superior com os tratamentos de água aquecida a 55 ºC por 30 s, 58 ºC por 15 s e 30 s e com as doses de radiação de 0,660 kJ m-2 e 1,320 kJ m-2. O controle do crescimento micelial de A. alternata e de M. roridum foi inferior com as doses de radiação e com a temperatura de 50 ºC quando comparados aos demais tratamentos. Na redução do crescimento micelial de F. pallidoroseum, os tratamentos a 58 ºC ou as doses de 0,660 kJ m-2 e 1,320 kJ m-2 foram mais eficiêntes, com controle superior a 88 %. Água aquecida a 58 ºC por 15 s controlou UFCs e o crescimento micelial dos patógenos testados.

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Soitinnus: orkesteri.