957 resultados para Solid phase microextraction


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

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The effects of chloride and nitrate anions and their respective concentrations, as well as urea presence, on solid phase morphologies were investigated. Zinc hydroxide carbonate was prepared by aging diluted zinc salt solution in presence of urea at 90ºC. Samples were identified by X-ray powder diffractograms showing the characteristic patterns of hydrozincite. The crystallinity was correlated with the concentrations of reagents. Spherulitic-type aggregates and single acicular particles were obtained from diluted chloride and nitrate solutions while porous aggregates of uniform size were formed from solutions with high chloride and urea concentrations.

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

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Argilas constituem uma classe de complexos micro-heterogêneos e podem ser utilizados como substrato para adsorção. O seu comportamento de sorção em fase sólida intensificada pela presença de surfactantes, argilas organofílicas, é um importante fenômeno explorado pela tecnologia ambiental para a remoção de compostos orgânicos policíclicos (hidrocarbonetos aromáticos policíclicos, HPA) da água, introduzidos no ambiente por fontes antropogênicas. Este trabalho tem por objetivo estudar o comportamento fotofísico do antraceno, como modelo de HPA, em sistemas micro-heterogêneos argila-surfactantes-íons metálicos (M(II)= Cd(II), Cu(II), Hg(II), Ni(II) e Pb(II); surfactantes: CTACl; SDS; TR-X100). Os estudos foram conduzidos pelo monitoramento na mudança das propriedades de fluorescência estática e na supressão da emissão do antraceno utilizado como sonda fluorescente. Como supressores foram utilizados os cátions metálicos: Cd(II), Cu(II), Hg(II), Ni(II) e Pb(II). O perfil do espectro de fluorescência e os resultados dos ensaios de supressão da fluorescência da sonda permitiram inferir na localização do sítio de solubilização do antraceno nos sistemas micro-heterogêneos estudados e na conseqüente organização dos mesmos.

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Eight Panthera onca (Po), 13 Felis concolor (Fc), 7 Felis yagouaroundi (Fy), 7 Felis tigrina (Ft) and 5 Felis pardalis (Fp) specimens from São Paulo State zoos were used. All animals were restrained with darts containing 10 mg/kg ketamine and 1 mg/kg xylazine. Venous blood samples were collected as soon as possible (within 15-20 min) and serum was frozen until the time for cortisol quantification. Cortisol was determined using a solid phase radioimmunoassay with an intra-assay coefficient of 8.51%. Data were analyzed statistically by the Kruskal-Wallis test, followed by Dunn's multiple comparisons test, and the one-sample t-test, with the level of significance set at P<0.05. Data are reported as means ± SEM. Cortisol levels differed among the captive felines: Po = 166 ± 33a, Fc = 670 ± 118b, Fy = 480 ± 83b, Ft = 237 ± 42ab, Fp = 97 ± 12a nmol/l (values followed by different superscript letters were significantly different (P<0.001)). Since most of the veterinary procedures on these species involve chemical restraint, these results show the necessity of preventive measures in order to minimize the effect of restraint stress on more susceptible species

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O tapir ou anta, descrito como o maior mamífero terrestre brasileiro, pertence à ordem Perissodactila, subordem Hippomorfa, superfamília Tapiroidea e família Tapiridae. Na floresta úmida está envolvido com a dispersão de sementes em função das características do tubo digestivo. O acompanhamento do ciclo estral permite avaliar e compreender a atividade reprodutiva nas espécies animais. Nos animais silvestres, o estresse da contenção pode interferir na própria ciclicidade gonadal, uma das alternativas é o acompanhamento dos hormônios gonadais nas excretas. Buscamos neste trabalho o acompanhamento periódico da atividade gonadal através da quantificação de progesterona no leite. Utilizamos uma fêmea recém-parida no Zoológico de Araçatuba, da qual colhemos leite, esfregaço vaginal e temperatura retal. A progesterona foi quantificada por radioimunoensaio de fase sólida (Coat-a-Count, DPC®) com curva padrão fornecida pela F.A.O. O ensaio mostrou sensibilidade de 1,25 nmol/l com coeficiente de variação intra-ensaio de 15,36%. Durante a fase de lactação, a fêmea não apresentou níveis detectáveis de progesterona por 158 dias (de novembro a abril). O primeiro pico de produção foi de 2,3 nmol/l e apresentou duração de 5 dias. O segundo pico de 3,54 nmol/l teve uma duração de 23 dias. Setenta e quatro dias após o aparecimento da progesterona no leite a lactação cessou. Podemos concluir que a fêmea de tapir apresentou um período de anestro lactacional de aproximadamente 5 meses e voltou a ciclar no outono (abril) sugerindo pouca influência do fotoperíodo. A quantificação da progesterona no leite mostrou-se útil para o acompanhamento do ciclo estral na espécie, porém a variação da citologia vaginal e temperatura retal não apresentaram correlação com os níveis hormonais.

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Cinco éguas mestiças (idade e peso corporal médios de seis anos e 480 kg PV) foram distribuídas em delineamento experimental em quadrado latino para se e avaliar a utilização de dietas contendo grãos de triticale (secos ou ensilados) em substituição ao milho na alimentação de eqüinos, por meio do ensaio de avaliação do trânsito gastrintestinal e da digestibilidade. Os tratamentos consistiram de três níveis de grãos de triticale em substituição aos grãos de milho (0, 50 e 100%) e duas formas de conservação dos grãos de triticale (secos ou ensilados). As dietas foram isoprotéicas (12,5% PB), com ingestão diária de MS pelos animais de 2,0% PV (relação volumoso : concentrado de 50:50). Os coeficientes de digestibilidade aparente (CDa) da MS, MO, PB e FDN foram determinados indiretamente. Os parâmetros de trânsito gastrintestinal avaliados foram: k1 (taxa de passagem pelo intestino grosso), k2 (taxa de passagem pelo estômago), TT (tempo de trânsito), TMR (tempo médio de retenção) e TMRT (tempo médio de retenção total). Não houve diferença para os CDa da MS, MO, PB e FDN entre as dietas experimentais, observando-se valores médios de 64,31; 65,14; 74,13 e 57,25%, respectivamente. Considerando-se a cinética das fases sólida e líquida, notou-se efeito somente para k2 na fase sólida da digesta, cujo valor nas rações contendo 100% de triticale (seco ou ensilado) foi de 19,63%/h e na dieta controle (0% de triticale), de 23,72%/h. Observou-se efeito linear crescente para o TT na fase sólida da digesta, com a elevação dos níveis de substituição dos grãos de milho pelos grãos de triticale ensilados. Concluiu-se que os concentrados para eqüinos podem ser formulados com grãos de triticale secos ou ensilados em substituição total ao milho. A inclusão de grãos de triticale na alimentação desta espécie animal promoveu trânsito lento da fase sólida da digesta.

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A new mast cell degranulating peptide, eumenine mastoparan-AF (EMP-AF), was isolated from the venom of the solitary wasp Anterhynchium flavomarginatum micado, the most common eumenine wasp found in Japan. The structure was analyzed by FAB-MS/MS together with Edman degradation, which was corroborated by solid-phase synthesis. The sequence of EMP-AF, Ile-Asn-Leu-Leu-Lys-Ile-Ala-Lys-Gly-Ile-lle-Lys-Ser-Leu-NH(2), was similar to that of mastoparan, a mast cell degranulating peptide from a hornet venom; tetradecapeptide with C-terminus amidated and rich in hydrophobic and basic amino acids. In fact, EMP-AF exhibited similar activity to mastoparan in stimulating degranulation from rat peritoneal mast cells and RBL-2H3 cells. It also showed significant hemolytic activity in human erythrocytes. Therefore, this is the first example that a mast cell degranulating peptide is found in the solitary wasp venom. Besides the degranulation and hemolytic activity, EMP-AF also affects on neuromuscular transmission in the lobster walking leg preparation. Three analogs EMP-AF-1 similar to 3 were snythesized and biologically tested together with EMP-AF, resulting in the importance of the C-terminal amide structure for biological activities. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

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To validate the use of the Cornell Net Carbohydrate and Protein System (CNCPS) under Brazilian conditions, the chemical composition, the potential and the effective degradabilities of the carbohydrate and protein subfractions, and the solid phase passage rate were determined for corn silage in diets with forage:concentrate ratios of 80:20 (DI) and 60:40 (D2) using Nellore cattle. The chromium mordant technique was used to determine the particulate passage rate of solids. For diet 2, there was a reduction in the potentially degradable dry matter (DM), and however not significant, a reduction in the degradation rates of neutral detergent Fiber (NDF, 49%) and neutral detergent insoluble nitrogen (NDIN, 32%), and an increase in the degradation rare of starch (ST, 25%). The use of lag time increased the effective DM degradation (EDDM) of corn silage in both diets (23% and 53% for D1 and D2, respectively). The concentrate ratios did not influence the particulate passage rate of the diets. The higher values related ro the availability of the protein subfractions may indicate a underestimation by CNCPS, Rnd(or) could be attributed to the Zebu animals used in this study.

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A method was developed for the differential-pulse cathodic stripping voltammetric determination of ceftazidime with a hanging mercury drop electrode using its reduction peak at -0.43 V in Britton-Robinson buffer pH 4.0. The optimum accumulation potential and time were -0.15 V and up to 60 s, respectively. Linear calibration graphs were obtained from 1 x 10(-8) M and 1.5 x 10(-7) M. The limit of determination was calculated to be 5 x 10(-9) M. The coefficient of variation was 4% (n = 7) at 1 x 10(-7) M ceftazidime. The effect of various components of urine on the voltammetric response was studied, and creatinine, uric acid, urea, and glucose were shown to interfere in the method. Ceftazidime bound to human albumin gives a unique stripping peak at -0.48 V. Recoveries of 87% +/- 2% of the ceftazidime (n = 5) were obtained from urine spiked with 1.27 mu g ml(-1) using C-18 solid phase extraction cartridges. (C) 1997 Academic Press.

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A solid-phase extraction and chromatography-flame ionization detection (GC-FID) method has been developed for the routine analysis of psoralen, bergapten, isopimpinellin and pimpinellin in creams and pomades employed in Brazil for the treatment of vitiligo. The calibration curve for psoralen was linear in the range 10-100 mu g ml(-1), for bergapten 5-90 mu g ml(-1), for pimpinellin 10-90 mu g ml(-1) and for isopimpinellin 5-100 mu g ml(-1). The best recoveries of the furanocoumarins in the creams analysed were 94-97%, whereas in the pomades, recoveries were 94-96%. The R.S.D. of the quantitative analysis of the furanocoumarins in the products analyses were within 5%. (C) 2000 Elsevier B.V. B.V. All rights reserved.

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The solvation properties of model resin and peptide-resins measured in ca. 30 solvent systems correlated better with the sum of solvent electron acceptor (AN) and electron donor (DN) numbers, in 1:1 proportion, than with other solvent polarity parameters. The high sensitivity of the (AN+DN) term to detect differentiated solvation behaviors of peptide-resins, taken as model of heterogeneous and complex solutes, seems to be in agreement with the previously proposed two-parameter model, where the sum of the Lewis acidity and Lewis basicity characters of solvent are proposed for scaling solvent effect. Besides these physicochemical aspects regarding solute-solvent interactions, important implications of this study for the solid phase peptide synthesis were also observed. Each class of peptide-resin displayed a specific salvation profile that was dependent on the amount and the nature of the resin-bound peptide sequence. Plots of resin swelling versus solvent (AN+DN) values allowed the visualization of a maximum salvation region characteristic for each class of resin. This strategy facilitates the selection of solvent systems for optimal solvation conditions of peptide chains in every step of the entire synthesis cycle. Moreover, only the AN and DN concepts allow the understanding of rules for solvation/shrinking of peptide-resins when in homogeneous or in heterogeneous mixed solvents.

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This work has been developed using a sylvestral fruit tree, native to the Brazilian forest, the Eugenia uniflora L., one of the Mirtaceae family. The main goal of the analytical study was focused on extraction methods themselves. The method development pointed to the Clevenger extraction as the best yield in relation to SFE and Soxhlet. The SFE method presented a good yield but showed a big amount of components in the final extract, demonstrating low selectivity. The essential oil extracted was analyzed by GC/FID showing a large range of polarity and boiling point compounds, where linalool, a widely used compound, was identified. Furthermore, an analytical solid phase extraction method was used to clean it up and obtain separated classes of compounds that were fractionated and studied by GC/FlD and GUMS. (c) 2006 Elsevier B.V. All rights reserved.