Resumo em Inglês:

The objective of this paper is to investigate the physical and chemical quality of the water of the Descoberto River during the dry and rainy seasons by measuring pH, temperature, electric conductivity, total dissolved solids, turbidity, color, alkalinity and NO3-, SO4(2-), PO4(3-), NH4+, Cl- and HCO3-, and the elements Sr, Mo, Cd, Y, Ti, Ca, V, Mg, Fe, Si, Ni, Zr, Cu, Al, Cr, Mn, Ba, Co, Zn, P, Na and K. The results showed high concentrations in both seasons, with dilution along the course of the river, minimizing for a while problems that compromise the quality of the water of this source. However, a progressive deterioration can occur due to an increase in the discharge of pollutants, resulting from population growth, agricultural activities and other factors.

Resumo em Inglês:

The bioassay-guided fractionation against Biomphalaria glabrata of hydroalcoholic extracts of Calophyllum brasiliense aerial parts led to the isolation of the coumarin, named (-) mammea A/BB. The compound had its structure determined by both spectroscopic techniques (NMR ¹H, NMR 13C, gHSQC, gHMBC and MS) and some literature comparison data. The probit analysis of (-) mammea A/BB showed LD50 = 0.67 ppm and LD90 = 1.47 ppm. In addition, the dichloromethane extract obtained from C. brasiliense leaves with significant molluscicidal activity against Biomphalaria glabrata was analyzed by HPLC-UV.

Resumo em Inglês:

This work proposes a simple, fast and inexpensive method to determine As in natural waters, using X-ray fluorescence. 50 µL of each sample containing 100 mg L-1 of yttrium as internal standard were deposited over a 2.5 µm thickness MylarTM film. The samples were dried at 50 °C for 2 h. X-ray spectra were obtained using an EDXRF apparatus. The accuracy was determined by analyte addition/recovery and by comparison with Hydride Generation Atomic Absorption Spectrometry (HG AAS). A recovery of about 100% was obtained and the results were in good agreement with HG AAS. The method showed a relative standard deviation of 6.8% and a detection limit of 10.5 µg L-1 of As.

Resumo em Inglês:

Tiquira is a traditional homemade alcoholic distillate produced in the Maranhão State (Brazil), gotten from cassava (Manihot esculenta, Crantz.). It can be normally found on street markets. Due to the addition of tangerine leaves, the original tiquira has a bluish color. Samples of this beverage were acquired in the local trade and analyzed from the spectroanalytical point of view. The results indicated that these drinks had been adulterated by the addition of crystal violet, a potencialy hazardous compound. The identification and quantification of crystal violet in 10 spiked samples was accomplished by UV-Vis spectrophotometry through the standard addition method. In order to verify the efficiency of the proposed method, experiments on the quantification and recovery were carried out and the results indicated a content of crystal violet in the 10-6 to 10-7 mol L-1 range.

Resumo em Inglês:

The development of cobalt catalysts to produce hydrogen from ethanol is the goal of this investigation. Co/Al2O3 catalysts were prepared by impregnation and characterized by atomic absorption, nitrogen adsorption, X-ray diffraction, Raman spectroscopy, temperature programmed reduction and carbon analysis. The catalysts contained Co3O4 oxide and Co3+ and Co2+ species interacting with alumina. The cobalt load affects the crystal size and the crystalline structure and higher Co loads influence the reaction mechanism, changing the selectivity of the catalysts, decreasing the amount of CO produced and avoiding the formation of products catalyzed by the support. The ethanol conversion was 50-70% with 10-<1% of CO in the hydrogen.

Resumo em Inglês:

Two new compounds, 5 and 8, and an epimeric mixture 4a/4b were isolated from hardwood of Auxemma glazioviana. Their structures and relative configurations were determined by modern spectroscopic analysis to be rel-10alpha,11alpha-epoxy-11beta-ethoxy-8alpha- hydroxy-2-methoxy -8abeta-methyl-5,6,7,8,8a,9,10,10abeta-octahydro-1,4-anthracenedione (or rel-2R,2aR,5R,5aS ,10bS,10cS-2-ethoxy-5-hydroxy-8-methoxy-5a-methyl- 2a,3,4,5,5a,6,10b,10c-octahydro-2H-anthra[9,1-bc]furan-7,10-dione, 4a), rel-10alpha,11alpha- epoxy-11alpha-ethoxy-8alpha-hydroxy-2-methoxy-8abeta-methyl-5,6,7,8,8a,9,10,10abeta-octahydro- 1,4-anthracenedione (or rel-2S,2aR,5R,5aS ,10bS,10cS-2-ethoxy-5-hydroxy-8-methoxy- 5a-methyl-2a,3,4,5,5a,6,10b10c-octahydro-2H-anthra[9,1-bc]furan-7,10-dione, 4b), rel-10alpha,11alpha-epoxy-8alpha,11-dihydroxy-2-methoxy-8abeta-methyl-5,6,7,8,8a,9,10,10abeta- octahydro-1,4-anthracenedione (or rel-2S,2aR,5R,5aS ,10bS,10cS-2,5-dihydroxy-8- methoxy-5a-methyl-2a,3,4,5,5a,6,10b,10c-octahydro-2H-anthra[9,1-bc]furan-7,10 -dione, 5) and rel-10,11-epoxy-8abeta-methyl-1,4,5alpha,9alpha-tetrahydroxy-5,6,7,8,8a,9,10,10a- octahydro-8-anthracenone (or rel-2aS,5aS,6R,10bR ,10c5-2a,6,7,10-tetrahydroxy-5a-methyl-2a,3,4,5,5a,6,10b,10c-octahydro-2H-anthra [9,1-bc]-furan-5-one, 8). In addition, known compounds were also isolated.

Resumo em Inglês:

Maltodextrin was produced from cassava and corn starch by enzymatic hydrolysis with alpha-amylase. The cassava starch hydrolysis rate was higher than that of corn starches in maltodextrin production with shorter dextrose equivalent (DE). DE values do not show directly the nature of the obtained oligosaccharides. Maltodextrin produced from cassava and corn starch was analysed by high performance liquid chromatography (HPLC), and the analysis showed that maltodextrin production differs according to the source of the starch. This is important in defining the application of the maltodextrin, according to its desired function.

Resumo em Inglês:

The present communication reports the isolation and identification of four triterpenoid saponins from the chloroform extract of the leaves of Tocoyena brasiliensis: 3-O-beta-D-quinovopyranosyl quinovic acid, 3-O-beta-D-quinovopyranosyl cincholic acid, 3-O-beta-D-glucopyranosyl quinovic acid and the 28-O-beta-D-glucopyranosyl ester derivative of quinovic acid as binary mixtures, respectively. From the ethanol extract a flavonoid identified as ramnazin-3-O-rutinoside was obtained. The structures of these compounds were assigned by data analysis of 1D and 2D NMR spectrometry and comparison with data recorded in the literature for these compounds.

Resumo em Inglês:

This article presents an evaluation of the pollution of river water by herbicides used in the culture of irrigated rice in Rio Grande do Sul State, Brazil. Firstly, a theoretical evaluation was made using the approaches suggested by EPA-USA, the "Groundwater Ubiquity Score" index and the Goss method to estimate the pollution possibilities. Afterwards, a monitoring program was established for the rivers of the area from 2001 to 2003 to investigate the presence of herbicide residues. The results indicate that the herbicides clomazone and propanil are the ones with larger presence and frequency in the analyzed samples. The theoretical forecast was confirmed by the results of the monitoring program.

Resumo em Inglês:

Phytochemical investigation of the hexane, ethyl acetate and methanolic extracts of roots and leaf stalks of Euterpe precatoria Mart. ("açaí"), afforded stigmast-4-en-6beta-ol-3-one (3); p-hydroxy benzoic acid (4); 3beta-O-D-glucopyranosyl-sitosterol (5); beta-sitosterol palmitate (6); mixtures of beta-sitosterol and stigmasterol (1 and 2), alpha-, beta-amirin and lupeol (7, 8 and 9), friedelin-3-one and 28-hydroxy-friedelin-3-one (10 and 11) and alpha-, beta-D-glucose (12, 13). Except for 1, 2 and 4, the other isolated constituents are described in the genus for the first time. Compounds 3 and 5 gave good results in the brine shrimp bioassay, which detects compounds with potential uses as antitumor agents, pesticides, etc..

Resumo em Inglês:

Microbial lipases have a great potential for commercial applications due to their stability, selectivity and broad substrate specificity because many non-natural acids, alcohols or amines can be used as the substrate. Three microbial lipases isolated from Brazilian soil samples (Aspergillus niger; Geotrichum candidum; Penicillium solitum) were compared in terms of their stability and as biocatalysts in the enantioselective esterification using racemic substrates in organic medium. The lipase from Aspergillus niger showed the highest activity (18.2 U/mL) and was highly thermostable, retaining 90% and 60% activity at 50 ºC and 60 ºC after 1 hour, respectively. In organic medium, this lipase provided the best results in terms of enantiomeric excess of the (S)-active acid (ee = 6.1%) and conversion value (c = 20%) in the esterification of (R,S)-ibuprofen with 1-propanol in isooctane. The esterification reaction of the racemic mixture of (R,S)-2-octanol with decanoic acid proceeded with high enantioselectivity when lipase from Aspergillus niger (E = 13.2) and commercial lipase from Candida antarctica (E = 20) were employed.

Resumo em Inglês:

This paper describes the separation of CO2 from a gas mixture containing 25% CO2, 4% O2 and 71% N2 using the pressure swing adsorption (PSA) technique. The adsorbent selected was the zeolite 13X due to its great adsorption capacity for CO2 and selectivity towards the other components of the gas mixture. The experimental technique was designed to identify the most important variables for the process and to optimize it. It is shown that the PSA technique can be used to separate CO2 from O2 and N2 to obtain an effluent containing 2% CO2 with 99% separation efficiency.

Resumo em Inglês:

Effluents generated by the textile industry are of environmental concern because of the presence of dyes with complex molecular structure, which confer them recalcitrant characteristics. Indigo is one of the most widely used dyes within the textile sector and studies have suggested that edible fungi may be capable of its biodegradation. A textile effluent was mixed with sugarcane bagasse and inoculated with Pleurotus sajor-caju, the decolorization being evaluated after 14 days, when the process was observed. Enzymatic activities of laccase, peroxidase and manganese peroxidase were determined, the production of these ligninolytic enzymes being evident and a synergism among them being likely in the decolorizing process.

Resumo em Inglês:

The Brazilian market has been showing a growing concern with nutritional values of oil components of foods. Chemical interesterification is a promising alternative to the current processes of modifying the consistency of oils. Chemical interesterification of deodorized palm oil was studied on a laboratory scale. The best results were obtained with 0.4% MeONa and heating for 20 min at 100 °C. These conditions are based on the largest variation in triacylglycerols as compared to a control. The trisaturated values varied from 6.2 to 9.9%, showing that the consistency of the oil improved for it to be used in margarines, without the formation of trans isomers.

Resumo em Inglês:

Coffee is a product consumed all around the world, Brazil being the biggest exporter. However, little is known about the difference in composition of the different brands in terms of bioactive substances. In the present study, ten of the most consumed brands of coffee in Rio de Janeiro were analyzed. Caffeine contents, trigonelline and total chlorogenic acid varied from 0.8 g/100g to 1.4 g/100g; 0.2 g/100g to 0.5 g/100g and from 3.5 g kg-1 to 15.9 g kg-1, respectively. The large heterogeneity observed in the amounts of the bioactive compounds can be attributed to different formulations of the various brands, as well as to different roasting conditions.

Resumo em Inglês:

Natural aroma compounds are of major interest to the food and fragrance industry. Vanillin (3-methoxy-4-hydroxybenzaldehyde) was isolated from the vanilla beans in 1816 and its world consumption has reached today about 12000 tons per year. But only approximately 50 tons per year are extracted from vanilla pods (Vanilla planifolia). The remainder is provided by synthetic vanillin. This review is about alternative processes to produce natural vanillin de novo or by biotransformation using biotechnological methods involving enzymes, microorganisms and plant cells.

Resumo em Inglês:

The sampling of volatile organic compounds using solid phase microextraction is reviewed and its principles are described. The development and application of solid phase microextraction in the sampling of VOCs are presented and discussed.

Resumo em Inglês:

The TBA test is essential to quality control of fat-containing food, being the test most applied to evaluate lipid peroxidation in fishery, meat and poultry products. It estimates malonaldehyde, a secondary oxidation product, by reacting with 2-thiobarbituric acid, forming a coloured complex, measured spectrophotometrically atlambda = 532 nm. Results are expressed as mg malonaldehyde per kg sample or frequently as "TBA value". There are four ways of quantifying it: by lipid extraction, direct heating, distillation or heat-acid extraction. This review intends to point out traditional, modified and alternative TBA test methods, besides enumerating advantages and drawbacks of each one.

Resumo em Inglês:

This work discusses the electrocatalytic processes taking place in the polymer electrolyte fuel cell electrodes, specifically the hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (ORR), because these are clear examples of electrochemical reactions favored by the use of electrocatalysts. Since the gaseous reactants are very little soluble in the electrolyte, the use of special electrodes, named gas diffusion electrodes, is required to promote easy and continuous access of reactant gases to the electrocatalytic sites. Besides this, other important aspects such as the use of spectroscopic techniques and of theoretical models to improve the knowledge of the electrocatalytic systems are shortly discussed.

Resumo em Inglês:

Combinatorial chemistry refers to techniques to rapidly fabricate tens, hundreds or even thousands of different micro samples. The analysis of the large number of samples generated by combinatorial methods requires highly efficient analytical methods. In this case, the challenges are due not only to the large number of samples to be analyzed, but also to the small amount of sample available for analysis. This paper describes the fundamentals of combinatorial chemical methods applied to discover of materials and the development in x-ray diffraction to analyze micro samples.

Resumo em Inglês:

Approximately every minute, somewhere in the world four people die from tuberculosis (TB), an infection of Mycobacterium tuberculosis with about 3 million deaths per year. In spite of these problems, unfortunaly, it is about 40 years that a novel drug was last introduced on the market. Due to the rapid spread of multi-drug resistant TB strains, resistant against all major anti-tuberculosis drugs, and the recent resurgence of the incidence of tuberculosis in association with the human immunodeficiency virus (HIV) infection and AIDS, we need urgently the development of new drugs to fight tuberculosis. This is covered in the present article.

Resumo em Inglês:

The demand for analytical methods suitable for accurate and reproducible determination of drug enantiomers has increased significantly in the last years. High-performance liquid chromatography (HPLC) using chiral stationary phases and capillary electrophoresis (CE) are the most important techniques used for this purpose. In this paper, the fundamental aspects of chiral separations using both techniques are presented. Some important aspects for the development of enantioselective methods, particularly for the analysis of drugs and metabolites in biological samples, are also discussed.

Resumo em Inglês:

The olefin metathesis reaction allows the exchange of complex alkyl units between two olefins, with the formation of a new olefinic link and a sub-product olefin usually ethylene. This reaction has found extensive application in the last ten years with the development of the Grubbs and Schrock catalysts, in total synthesis of complex organic molecules, as opposed to the very important use in the petrochemical industry with relatively simple molecules. This review intends to trace a historical and mechanistic pathway from industry to academy, before illustrating the more recent advances.

Resumo em Inglês:

The indan ring system is present in several compounds with important pharmacological properties. In this account recent examples of selected methods (Friedel-Crafts acylation, cycloaddition reactions, ring contraction, cyclization and resolution) for the synthesis of indans are discussed.

Resumo em Inglês:

The results suggest that the two variables studied are significant and that they may be independently optimized. The material of the sample holder interferes with the incineration process only due to the amount of heat transfered. The sample holder volume aids diffusion of the atmosphere to the honey sample, minimizing the foaming effect. According to the results, for the thermogravimetric analysis of ash content in honey, sample holders of platinum or alumina of 150 µL are indicated.

Resumo em Inglês:

KBrO3 is registered by the FAO/OMS as a genotoxic and carcinogenic compound. In spite of this, KBrO3 is still employed by Brazilian bakeries. Nowadays ion exchange chromatography (IEC) is the most rapid and trustful method for BrO3- analysis. When at high concentrations, chloride ions can interfere in the BrO3- analysis, if the detection is performed by electrical conductivity. On the other hand, spectrophotometric detection, presented here is based on the absorption of BrO3- in the ultraviolet region (210 - 230 nm) where the absortion of chloride ions is very low, thus making possible the qualitative and quantitative analysis of BrO3- in flour improver samples.

Resumo em Inglês:

Plant extracts are usually complex mixtures which contain several molecules of different sizes with varied functional groups. Such extracts are a challenge to the chemist of natural products. Ion exchange chromatography in non-aqueous medium, used for separation of basic or acidic fractions from plant extracts, is an important unit operation in preparative scale separations. Anionic macroporous resin in non-aqueous medium was used with success in this study for separation of the acid fraction of Copaifera multijuga (Copaiba oil), rich in labdanic diterpenes and for the methanolic extract of Croton cajucara (acetyl aleuritoric acid).

Resumo em Inglês:

The present paper describes the synthesis of crystalline zirconium hydrogen phosphate by direct precipitation and its intercalation with pyridine and n-butylamine. The simple experiment was tested in the undergraduate inorganic chemistry laboratory course for chemistry students at IQ-UNICAMP using inexpensive reagents. The materials were characterized by powder X-ray diffraction and infrared analyses in order to obtain detailed information of the solid structure changes as a result of the intercalation process. Pyridine and n-butylamine are focused in this work as clear and elucidative examples leading to acid-base interactive processes that result in the well-formed infinite sequence of inorganic lamellar structures.

Resumo em Inglês:

The total synthesis of sulfadiazine and silver sulfadiazine from readily available starting materials was adapted to semi-micro laboratory scale and is proposed as an experiment in drug synthesis for undergraduate courses.

Resumo em Inglês:

The aim of this work is to establish a program for the treatment of chemical residues and waste waters at the Centro de Energia Nuclear na Agricultura (CENA/USP), for environmental preservation and training of staff. Five tons of stored residues and the ones currently generated in the laboratories have to be treated. Rational use of water is also part of the program. The traditional purification by distillation has been replaced by purification with ion exchange resins. Lower energy consumption and better water quality were achieved.

Resumo em Inglês:

Essential aspects for characterization of a flow-based analytical procedure or system are discussed in order to permit the composition of a checklist that will lead to a protocol for reporting results and systems in flow analysis. Aspects more related to chromatographic procedures are not considered. The intent is to present normalized proposals in the field of flow analysis for practitioners and developers.