Variabilidade química de compostos orgânicos voláteis e semivoláteis de populações nativas de Maytenus ilicifolia

This work is focused on the chemical distribution of volatile and semi-volatile compounds of 18 native populations of Maytenus ilicifolia collected all over Brazil. The extracts of bulk samples (30 plants) of each population were obtained by supercritical CO2 extraction technique, and analyzed by GC/MS. The quantification of compounds (phytol, squalene, vitamin E, limonene, stigmasterol, friedelan-3-ol, friedelin, fridelan-3-one, palmitic acid and geranyl acetate) showed significant variations within the different populations, which could be related tom microclimate characteristics.

Otimização e validação de método para determinação de ácidos orgânicos em vinhos por cromatografia líquida de alta eficiência

The organic acids (tartaric, malic, citric, lactic and succinic) are de main components responsible for the acidity in the wine. This method for simultaneous determination of organic acids and interfering peaks in wines can be achieved in 16 min. The sample preceded by a dilution and filtration step. The chromatographic separation required one reversed phase column, isocratic mobile phase (acetonitrila, formic acid in water) and detection wavelength was set at 212 nm. The validation confirmed good repeatability, recovery and application in red and white wines.

Pilhas de combustíveis microbianas utilizadas na produção de eletricidade a partir de rejeitos orgânicos: uma perspectiva de futuro

In this review is presented an innovative technology for use of animal and vegetable waste with high pollution levels in microbial fuel cell (MFC) as an alternative to waste remediation and simultaneously producing electricity and fertilizer for agriculture. A brief history of MFC, the studies about the electron transfer mechanisms, discussion of the biological nanowires in bacteria and the use of chemical mediators or carriers of electrons are explained. The factors influencing the performance of MFCs, the application in waste and sewage treatment and power generation are also discussed.

Métodos para determinação de atividade antioxidante in vitro em substratos orgânicos

In the literature there are a considerable number of chemical and biochemical tests for evaluation of in vitro antioxidant activities of pure compounds or fractions and organic extracts. These tests are important tools for screening of synthetic and natural bioactive compound as well as they can be employed in food chemistry. This work is a critical review of the main methods employed for in vitro antioxidant determination.

Estanilenos: organometálicos de estanho (II) σ - ligados a grupos orgânicos

This article provides a short review of the chemistry of stannylenes and their derivatives, including the preparation, spectroscopic properties, molecular structure and reactivity of the various species. The organometallic chemistry of Sn(II) is far less explored than that of its much more common Sn(IV) counterpart. Organometallics of main group metals have become increasingly important in recent years, which prompted us to present an overview of the situation regarding the case of Sn(II).

Recentes aplicações sintéticas de compostos orgânicos tricloro(bromo)metila substituídos

This review presents the recent applications of some trihalomethyl carbinols, α,α,α-trihalogenated carbonyl compounds and trichloro(bromo)methyl-containing heterocycles, acting as high versatile synthetic precursors in organic chemistry, based on the last 10 years' literature.

Ácidos orgânicos em aguardentes produzidas em alambique e em coluna

The concentration of 14 organic acids of 50 sugarcane spirits samples was determined by gas chromatography using flame ionization detection. The organic acids analytical quantitative profile in stills and column distilled spirits from wines obtained from the same must were compared. The comparison was also carried in "head", "heart" and "tail fractions of stills distilled spirits. The experimental data were analyzed by Principal Components Analysis (PCA) and pointed out that the distillation process (stills and column) strongly influences the lead spirits' organic acid composition and that producers' operational "cuts off" to produce "tail", "heart" and "head", fractions should be optimized.

Reciclagem do crômio de resíduos químicos provenientes da determinação de carbono oxidável em fertilizantes orgânicos

This work proposes a separation, recovery and reuse procedure of chemical residues with chromium. This residue was generated by the determination of oxidizable carbon in organic fertilizers samples. The Cr(VI) of the residue was reduced with ethanol and precipitated with NaOH. The Cr(OH)3 precipitate was separated and oxidized to dichromate ions with hydrogen peroxide. This solution was used another time in organic carbon determination. The uses of recycled dichromate solution were appropriated in four successive recycling. The accuracy was proven using potassium hydrogen phthalate and ten organic fertilizer samples. The organic carbon results, determined with recycled solutions, were similar the conventional solution.

Validação de método para determinação de ácidos orgânicos voláteis em efluentes de reatores anaeróbios empregando cromatografia líquida

This work deals with the method validation for the determination of acetic, propionic and butyric acids (VFAs) in wastewaters from anaerobic reactors by HPLC-DAD. Separation was performed using a C18 column and the mobile phase composition were water pH 3.0 and methanol 90:10 (v/v). The detection and quantification was carried out at 220 nm. The method shows good linearity (r²>0.996), with adequate accuracy (89-102%) and relative standard deviations lower than 18%. The matrix effect was considered low (-4.1, -3.9 and 1.4%). The developed method is fast, simple and cheap; and it was applied in wastewater samples from anaerobic reactor.

Utilização de eletrodos sólidos de amálgama para a determinação analítica de compostos orgânicos e inorgânicos

This review reports the use of solid amalgam electrodes in the electroanalytical determination of organic and inorganic compounds. The different types of amalgam electrodes are presented, and attention is paid to solid amalgam electrode, and here is presented details about the pre-treatment for activation and renovation and also possible modifications in its surface. The wide potential range, higher signal-to-noise ratio, mechanical stability enabling their application in flowing systems, and principally their resistance toward passivation, indicate that the solid amalgam electrodes are environmentally friendly alternatives to mercury electrodes, without loss in the sensitivity and reproducibility in voltammetric responses.

Aplicações de cromatografia líquida de alta eficiência para o estudo de poluentes orgânicos emergentes

Emerging organic pollutants (EOP) include many environmental contaminants based on commercial products such as pharmaceuticals, personal care products, detergents, gasoline, polymers, etc. EOP may be candidates for future regulation as they offer potential risk to environmental and human health due to their continual entrance into the environment and to the fact that even the most modern wastewater treatment plants are not able to totally transform / remove these compounds. High performance liquid chromatography is recommended to separate emerging organic pollutants with characteristics of high polarity and low volatility, especially pharmaceuticals, from environmental matrices.

Caracterização cromatográfica de compostos orgânicos presentes nos resíduos sólidos provenientes de indústria de reciclagem de papel e sua aplicação na produção de briquetes de carvão vegetal

Recycling of paper in industrial scale has become an established practice worldwide. In this work, organic compositions of three different kinds of sludge generated in recycle paper industry were studied, and the incorporation of one of those sludge in briket was also investigated. The characterization of organic compounds in sludge samples and briket was performed using Gas Chromatography coupled with Mass Spectrometry after a Soxhlet extraction. Different chemical classes were identified in each type of sludge, but just the sludge composed by cellulose residue did not presented polyaromatic hydrocarbons. Four formulations of sludge incorporated with charcoal for briket production were evaluated.

Triagem de suportes orgânicos e protocolos de ativação na imobilização e estabilização de lipase de Thermomyces lanuginosus

Lipase from Thermomyces lanuginosus was covalently immobilized on activated poly-hydroxybutyrate, sugarcane bagasse and the chemically modified hybrid hydrogel chitosan-alginate prepared by different strategies. Among the tested supports, chitosan-alginate chemically modified with 2,4,6-trinitrobenzenesulfonic acid rendered derivatives with the highest hydrolytic activity and thermal-stability, 45-fold more stable than soluble lipase and was then selected for further studies. The pH of maximum activity was similar for both immobilized and free lipase (pH 8.0) while optimum temperature was 5 - 10 ºC higher for the immobilized lipase. Higher yields in the butyl butyrate synthesis were found for the derivatives prepared by activation with glycidol and epichlorohydrin.

Ácidos orgânicos de baixa massa molar em solos e materiais orgânicos

Determination of organic acids in soils and organic materials is important due to the important role they play in improving the soil's physical, chemical and microbiological conditions. This study identified and quantified low molecular weight organic acids (LMWOA) in soils (dystroferric Red Latosol, dystrophic Red-Yellow Latosol and Quartzarenic Neosol) and organic materials (cow, pig, chicken, quail and horse manures, sawdust, coconut fiber, pine bark, coffee husks, biochar, organic substrate, sewage sludges 1 and 2, garbage compost, pig slurry compost). The following acids were identified: acetic, citric, D-malic, formic, fumaric, maleic, malonic, oxalic, quinic, shikimic, succinic and tartaric.

Processo de estabilização de resíduos orgânicos: vermicompostagem versus compostagem

Two processes are used to stabilize organic wastes: composting and vermicomposting.There are no studies in the literature showing which process is most effective over the short term. In this study, 3 organic wastes were composted and vermicomposted for 90 days, and the parameters pH, effective cation exchange capacity, total organic carbon, total Kjeldahl nitrogen, Ptotal, E4/E6 ratio, hydrophobicity and aromaticity indexes were determined. In all experiments, vermicomposted materials showed higher stability, proving a superior tool for stabilization of these organic wastes.