A qualidade do ar de interiores e a química

In Brazil, very little experimental work on measurements of indoor air pollutant levels has been done. Nowadays, increasing attention is being given to indoor air quality and the health problems associated with buildings and the indoor work environment. The scope of this paper is to review the major pollutants found in indoor environments and their sources. Subsequently, exposure to indoor air pollutants and health effects are considered. The review concludes by briefly addressing assessment of indoor air quality in Brazil and research needs.

Inserção do conceito de economia atômica no programa de uma disciplina de química orgânica experimental

In this paper, the atom economy concepts are applied in a series of experiments during an experimental organic chemistry class, to implement "green chemistry" in an undergraduate course.

Constituintes químicos de Alchornea glandulosa (Euphorbiaceae)

Chemical investigation of the leaves of Alchornea glandulosa (Euphorbiaceae) afforded a mixture of b-sitosterol and stigmasterol, the terpenoid loliolide, the guanidine alkaloid N-1,N-2,N-3-triisopentenylguanidine and the phenolic compound corilagin. The structures of these compounds were elucidated by spectroscopic analysis. The antimicrobial and antiproliferative properties of the crude methanolic extract of the leaves and of fractions from its fractionation, were investigated against a series of bacteria and fungi, as well as against four human cancer cell lines.

Validação de metodologia analítica para doseamento de soluções de lapachol por CLAE

Lapachol is a naphthoquinone found in several species of the Bignoniaceae family possessing mainly anticancer activity. The present work consists of the development and validation of analytical methodology for lapachol and its preparations. The results here obtained show that lapachol has a low quantification limit, that the analytical methodology is accurate, reproducible, robust and linear over the concentration range 0.5-100 µg/mL of lapachol.

Ultra-trace monitoring of copper in environmental and biological samples by inductively coupled plasma atomic emission spectrometry after separation and preconcentration by using octadecyl silica membrane disks modified by a new schiff's base

Ultra-trace amounts of Cu(II) were separated and preconcentrated by solid phase extraction on octadecyl-bonded silica membrane disks modified with a new Schiff,s base (Bis- (2-Hydroxyacetophenone) -2,2-dimethyl-1,3-propanediimine) (SBTD) followed by elution and inductively coupled plasma atomic emission spectrometric detection. The method was applied as a separation and detection method for copper(II) in environmental and biological samples. Extraction efficiency and the influence of sample matrix, flow rate, pH, and type and minimum amount of stripping acid were investigated. The concentration factor and detection limit of the proposed method are 500 and 12.5 pg mL-1, respectively.

A novel method for fast enrichment and monitoring of hexavalent and trivalent chromium at the ppt level with modified silica MCM-41 and its determination by inductively coupled plasma optical emission spectrometry

Chromium(III) at the ng L-1 level was extracted using partially silylated MCM-41 modified by a tetraazamacrocyclic compound (TAMC) and determined by inductively coupled plasma optical emision spectrometry (ICP OES). The extraction time and efficiency, pH and flow rate, type and minimum amount of stripping acid, and break- through volume were investigated. The method's enrichment factor and detection limit are 300 and 45.5 pg mL-1, respectively. The maximum capacity of the 10 mg of modified silylated MCM-41 was found to be 400.5±4.7 µg for Cr(III). The method was applied to the determination of Cr(III) and Cr(VI) in the wastewater of the chromium electroplating industry and in environmental and biological samples (black tea, hot and black pepper).

Análises quali- e quantitativa de cafés comerciais via ressonância magnética nuclear

Coffee is one of the beverages most widely consumed in the world and the "cafezinho" is normally prepared from a blend of roasted powder of two species, Coffea arabica and Coffea canephora. Each one exhibits differences in their taste and in the chemical composition, especially in the caffeine percentage. There are several procedures proposed in the literature for caffeine determination in different samples like soft drinks, coffee, medicines, etc but most of them need a sample workup which involves at least one step of purification. This work describes the quantitative analysis of caffeine using ¹H NMR and the identification of the major components in commercial coffee samples using 1D and 2D NMR techniques without any sample pre-treatment.

Reversed phase HPLC determination of tamoxifen in dog plasma and its pharmaco-kinetics after a single oral dose administration

The analytical method developed to evaluate tamoxifen in dog plasma samples was precise, accurate, robust and linear in the range of 5-200 ng/mL. The limits of detection and quantification were 0.981 ng/mL and 2.97 ng/mL, respectively. Besides, the intra-day precision and accuracy variations were 8.78 and 10.16%, respectively. Tamoxifen concentrations were analyzed by combined reversed phase liquid chromatography and UV detection (lambda=280 nm). The study was conducted using an open randomized 2-period crossover balanced design with a 1-week washout period between the doses. This simple, rapid and selective method is suitable for pharmacokinetic, bioavailability and bioequivalence studies.

Modificação química e física do amido de quirera de arroz para aproveitamento na indústria de alimentos

The study evaluated the efficiency of chemical (phosphorylation) and physical (extrusion) modifications of the starch of broken rice. Results demonstrated a reduction in the moisture content of extruded and phosphorylated broken rice and an increase in the ash content of phosphorylated broken rice. Both phosphorylation and extrusion increased cold water binding capacity, swelling power, and solubility. Extruded and phosphorylated pastes were stable under refrigeration, but only extruded paste was stable when submitted to freezing. Phosphorylated paste had the lowest viscosity and the highest stability during heating, while the extruded one gelatinized without heating, but had higher losses during heating.

Ambiental volatile organic compounds in the megacity of São Paulo

In order to characterize the composition of the main urban air organic compounds in the megacity of Sao Paulo, analysis of samples collected during the winter of 2003 downtown was carried out. The samplings were performed on the roof of a building in the commercial center of São Paulo. Hydrocarbons and carbonyls compounds were collected on August 4, 5 and 6. Comparing to previous data, the concentration of hydrocarbons presented no decrease in the concentration, except for the aldehydes, which decreased when compared to previous data. Among the HCs species analyzed, the highest concentrations observed were those of toluene (7.5 ± 3.4 ppbv), n-decane (3.2 ± 2.0 ppbv), benzene (2.7 ± 1.4 ppbv) and 1,3,5-trimethylbenzene (2.2 ± 1.5 ppbv).

Polissacarídeos da biodiversidade brasileira: uma oportunidade de transformar conhecimento em valor econômico

A brief comment about general characteristics of polysaccharide was presented. Brazilian trade of polysaccharides was obtained from the "Ministério de Desenvolvimento, Indústria e Comércio Exterior" - Brazil. A list of these products was prepared and their price and amount analyzed in the period of 1998-2007. Some chemical properties and application of polysaccharides from our biodiversity was described. In this review they were classified by origin, in vegetal (exudate, seed, fruit, seaweed), animal and bacteria source. There is a trade deficit that can be reverted if part of the accumulated scientific knowledge was used to promote the national economic development in the field.

Desenvolvimento de sistemas líquido-cristalinos empregando silicone fluido de co-polímero glicol e poliéter funcional siloxano

For the construction of the phase diagrams, the method of the aqueous titration was used. There were prepared 5 ternary diagrams, varying the surfactant and the oil phase. The liquid-crystalline phases were identified by polarized light microscopy. The formulations prepared with silicon glycol copolymer, polyether functional siloxane (PFS) and water (S1) and with diisopropyl adipate, PFS and water (S4) presented liquid-crystalline phases with lamellar arrangement. Moreover, after 15 days in hot oven (37 ºC), the formulations presented hexagonal arrangement, evidencing the influence of the temperature in the organization of the system.

Temperature measurements by oh lif and chemiluminescence kinetic modeling for ethanol flames

OH LIF-thermometry was applied to premixed ethanol flames at atmospheric pressure in a burner for three flame conditions. Flame temperatures were simulated from energy equation with PREMIX code of CHEMKIN software package for comparison. A kinetic modeling based on a model validated through chemiluminescence measurements and on a set of reactions for nitrogen chemistry was evaluated. Marinov's mechanism was also tested. Sensitivity analysis was performed for fuel-rich flame condition with Φ = 1.34. Simulated temperatures from both reaction mechanisms evaluated were higher than experimental values. However, the proposed kinetic modeling resulted in temperature profiles qualitatively very close to the experimental.

Poluição e a densidade de vegetação: BTEX em algumas áreas públicas de Curitiba - PR, Brasil

The occurrence of benzene, toluene, ethylbenzene, and xylenes (BTEX) in some public areas of Curitiba-PR, Brazil, was evaluated. Their concentrations were then related to the vegetation's density in each area. Average benzene concentrations varied from 3.9 to 6.1 μg m-3, with higher values occurring in poorly dense vegetation areas. For toluene, average concentrations ranged from 6.5 to 7.2 μg m-3. The effect of such pollutants was evaluated by means of a bio indicator, Tillandsia stricta. Variation in total chlorophyll content and in stomatic density were detected in some samples and may be related to the BTEX concentrations found in the studied areas.