Gas chromatographic analysis of indole alkaloids from Tabernaemontana hilariana

A fast and efficient procedure was elaborated to identify the alkaloid constituents from Tabernaemontana hilariana (Apocynaceae). The strategy based on fractioning of the crude alkaloid fraction in small silica cartridges followed by thin-layer chromatography (TLC), capillary gas chromatography-flame ionization detection as well as high-resolution gas chromatography-mass spectrometry afforded voacangine, coronaridine, ibogamine, voacangine pseudoindoxyl, voacangine hydroxyindolenine, 3-hydroxycoronaridine and 3-(2-oxopropyl)coronaridine. (C) 1997 Elsevier B.V. B.V.

Screening Brazilian C gasoline quality: Application of the SIMCA chemometric method to gas chromatographic data

A total of 2400 samples of commercial Brazilian C gasoline were collected over a 6-month period from different gas stations in the São Paulo state, Brazil, and analysed with respect to 12 physicochemical parameters according to regulation 309 of the Brazilian Government Petroleum, Natural Gas and Biofuels Agency (ANP). The percentages (v/v) of hydrocarbons (olefins, aromatics and saturated) were also determined. Hierarchical cluster analysis (HCA) was employed to select 150 representative samples that exhibited least similarity on the basis of their physicochemical parameters and hydrocarbon compositions. The chromatographic profiles of the selected samples were measured by gas chromatography with flame ionisation detection and analysed using soft independent modelling of class analogy (SIMCA) method in order to create a classification scheme to identify conform gasolines according to ANP 309 regulation. Following the optimisation of the SIMCA algorithm, it was possible to classify correctly 96% of the commercial gasoline samples present in the training set of 100. In order to check the quality of the model, an external group of 50 gasoline samples (the prediction set) were analysed and the developed SIMCA model classified 94% of these correctly. The developed chemometric method is recommended for screening commercial gasoline quality and detection of potential adulteration. (c) 2007 Elsevier B.V. All rights reserved.

Gas Chromatographic Determination of Cyprodinil, Fludioxonil, Pyrimethanil, and Tebuconazole in Grapes, Must, and Wine

A rapid and simple gas chromatographic method for determinating cyprodinil, fludioxonil, pyrimethanil, and tebuconazole in grapes, must, and wine is described. An on-line microextraction method was used with a one-step extraction-partition procedure. Nitrogen-phosphorus and mass spectrometric detectors were used, because of their low sensitivity and high selectivity. Because of high selectivity of detector, no cleanup was necessary and the extract was concentrated 5 times. Recoveries from fortified grapes, must, and wine ranged from 93 to 110%. Limits of determination were 0.05 mg/kg for cyprodinil and pyrimethanil and 0.10 mg/kg for fludioxonil and tebuconazole.

A simple and rapid extraction for gas chromatographic determination of thiabendazole and imazalil residues in lemons

A rapid and efficient method is described for the determination of thiabendazole and imazalil residues in lemons (peel and pulp). The procedure is based on the extraction with an hexane:ethyl acetate mixture (1:1, v/v) and gas chromatographic analysis using thermionic specific detection (TSD). The possibility of matrix effect was also studied. Mean recoveries from 8 replicates of fortified samples ranged from 79% to 109%, with relative standard deviation values between 2.4% to 12.8%. The detection and quantification limits of the method were 0.2 mg kg-1 and 0.5 mg kg-1, respectively.

Soil greenhouse gas emissions and their relations to soil attributes in a sugarcane area

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

Additional steps in mechanical recyling of PET

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

Characterization of Post-Consumer PET after Removal of the Original Surface: Influence of Raw Material

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

Characterization of the Interactions between Endocrine Disruptors and Aquatic Humic Substances from Tropical Rivers

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

Study of caffeine urine and saliva of horses subjected to urinary acidification

The study of caffeine in racing horses has been of growing concern in veterinary sports medicine since the Association of Racing Commissioners International (ARCI) stated that it has no valid therapeutic use in racehorses. We examined the kinetic alterations in the urinary excretion and salivary secretion of caffeine in seven horses subjected to urinary acidification using ascorbic acid because this procedure can simulate the acidosis that follows anaerobic exercise. They participated in two treatment groups: the control group (SG) received 500 ml of saline and then 2.0 mg kg(-1) caffeine i.v. 30 min later; and the acidified group (AG) was subjected to urinary acidification with ascorbic acid at a dose of 0.5 g kg(-1) i.v. and then 2.0. mg kg(-1) caffeine i.v. 30 min later. Samples were collected 30 min before caffeine administration, immediately before caffeine administration (time zero) and at 0.25, 0.5, 1, 2, 4, 6, 8, 12, 24, 48 and 72 h afterwards. The samples were assayed by gas chromatography. The mean urinary pH for SG was 8.2, but for AG it was as low as 5.9 at 4 h, extending acidosis for up to 8 h. The kinetic curves for the two groups were similar for urinary excretion and salivary secretion. Differences occurred only in peak excretion and peak secretion in SG obtained at 1 h and 30 min, respectively, and in AG at 2 h and 1 h, respectively. This could be explained, in part, to the diuresis in AG compared with SG, resulting in less concentrated urine in the former group. The large difference between the pK(a) of caffeine and the pH of the medium may be responsible for the similar pharmacokinetics observed for the two groups. Copyright (C) 2004 John Wiley Sons, Ltd.

Ruminal methane emission by dairy cattle in Southeast Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sazonalidade dos ductos secretores e óleo essencial de Foeniculum vulgare var. vulgare Mill. (Apiaceae)

Este trabalho teve como objetivo analisar os ductos secretores e o óleo essencial das folhas de Foeniculum vulgare em diferentes épocas do ano. Para esta finalidade, foram realizados estudos de caracterização anatômica, bem como anatomia comparada dos ductos secretores e testes histoquímicos das folhas. O óleo essencial foi obtido de folhas e frutos, por hidrodestilação em aparelho de Clevenger e analisados quantitativamente e qualitativamente por cromatografia em fase gasosa acoplada ao espectrômetro de massa, realizando-se análises seguidas de três réplicas para folhas coletadas durante o inverno e primavera, e frutos no verão. Os resultados encontrados para os ductos secretores de óleo corresponderam à redução do teor de óleo essencial nas folhas coletadas no final da primavera. O componente majoritário do óleo essencial de folhas e frutos foi o trans-anetol, durante todas as estações do ano. Portanto, evidenciou-se que os ductos secretores e teor de óleo essencial estão relacionados, bem como os constituintes químicos também estão sujeitos a sazonalidade, conforme o estágio fenológico da planta.

Produção de fitomassa, teor e produtividade do óleo essencial de Baccharis dracunculifolia DC. em função da adubação orgânica

Objetivou-se avaliar a produção de fitomassa, teor e produtividade do óleo essencial de Baccharis dracuculifolia DC., em função de doses de adubo orgânico, e foram utilizadas mudas produzidas por semente, e mantidas sob sombrite pelo período de 84 dias até serem transplantadas para o campo, no espaçamento de 1,0 x 1,0 m, com irrigação por gotejamento. O delineamento estatístico utilizado foi em blocos ao acaso, com quatro repetições, e as doses de composto orgânico foram: 0, 10, 20, 30, 40 e 50 t ha-1. Foi realizada uma colheita, aos 150 dias após o transplante das mudas. O óleo essencial foi extraído por hidrodestilação e analisado em cromatógrafo a gás acoplado a espectrômetro de massas (Shimadzu, QP-5000). Todos os resultados foram submetidos à análise de variância pelo teste F seguido da análise de regressão e o teste Tukey para os dados: massa seca útil da parte aérea, teor e produtividade do óleo essencial. Para as variáveis massa seca total e massa seca útil da parte aérea, as dosagens estudadas influenciaram as plantas, que apresentaram os melhores resultados na dose 50 t ha-1. Para teor de óleo não houve influência significativa para as dosagens estudadas, porém a dose 30 t ha-1 apresentou o melhor resultado. Entretanto para a produtividade do óleo essencial, as dosagens estudadas influenciaram as plantas, que na dosagem 30 t ha-1 obtiveram os melhores resultados.

Volatile compounds from organic and conventional passion fruit (Passiflora edulis F. Flavicarpa) pulp

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

Identification and migration of degradation compounds from irradiation of multilayer polyamide 6 films for meat foodstuffs and cheese

The aim of this work was to identify the degradation compounds produced during irradiation of multilayer polyamide 6 (PA-6) films and to study their migration into water and 95% ethanol food simulant. After irradiation of multilayer PA-6 films at 3, 7 and 12 kGy, degradation compounds were extracted using solid-phase microextraction, for which the time and temperature of extraction and stirring were optimized, and identified by gas chromatography-mass spectrometry. Caprolactam, 2-cyclopentylcyclopentanone and aldehydes, among other compounds, were identified in the headspace of the films. Polydimethylsiloxane was considered the best fiber for extraction. The optimum conditions of time, temperature and stirring to extract the compounds were 20 min, 80 degrees C and 225 rpm. For validation purposes, the compounds were quantified in water and 95% ethanol and the results showed high sensitivity, good precision and accuracy. Migration of compounds from irradiated and non-irradiated multilayer PA-6 films into water and 95% ethanol food simulants was carried out at 40 degrees C for 10 days. The method was efficient for the quantification of decaldehyde, 2-cyclopentylcyclopentanone and caprolactam that migrated from multilayer PA-6 films into food simulants.