Simultaneous determination of B-Group vitamins in enriched cookies

The objective of this research was to determine the levels of enrichment of vitamins B1, B2, B6 and B3 in different types and brands of enriched cookies. The chromatographic separation was performed in a C18 column with gradient elution and UV detection at 254 and 287 nm. The results show that only 5 of the 24 brands evaluated are in accordance with the Brazilian legislation with respect to the vitamin content declared on the labels. However, consumption of approximately 100-150 g of most of the brands supplies the recommended dietary intake for children and adults of the vitamins evaluated.

Síntese e estudo de ortossilicatos de zinco luminescentes com aplicação da técnica sol-gel

Usually, the concepts of the Sol-Gel technique are not applied in experimental chemistry courses. This work presents a feasible experiment for chemistry instruction, which involves the synthesis of luminescent materials - Zn2SiO4, with and without Mn2+ as a dopant - by the Sol-Gel technique. The obtained materials were analyzed by scanning electron microscopy, X-Ray diffraction, IR spectroscopy and luminescence measures by UV-vis spectroscopy. The results allow the students to confirm the luminescent properties of the zinc orthosilicate luminophores as well as the structural features expected from literature data.

Synthesis, characterization, DFT and Td-dfT study of the [Fe(mnt)(L)(t-BuNC) 2] octahedral complex (L = phen, bipy)

FeBr2 has reacted with an equivalent of mnt2- (mnt = cis-1,2-dicyanoethylene-1,2-dithiolate) and the α-diimine L (L = 1,10'-phenantroline, 2,2'-bipyridine) in THF solution, and followed by adding of t-butyl-isocyanide to give [Fe(mnt)(L)(t-BuNC)2] neutral compound. The products were characterized by infrared, UV-visible and Mössbauer spectroscopy, besides thermogravimetric and conductivity data. The geometry in the equilibrium was calculated by the density functional theory and the electronic spectrum by the time-dependent. The experimental and theoretical results in good agreement have defined an octahedral geometry with two isocyanide neighbours. The π→π* intraligand electronic transition was not observed for cis-isomers in the near-IR spectral region.

Desenvolvimento e validação de método espectrofotométrico para determinação de corante à base de luteína adicionado em iogurte desnatado

A simple analytical method for extraction and quantification of lutein colorant added to yogurt was developed and validated. The method allowed complete extraction of carotenoids using tetrahydrofuran in vortex, followed by centrifugation, partition to diethyl ether/petroleum ether, and drying. The carotenoids dissolved in ethanol were quantified by UV-Vis spectrophotometry. This method showed linearity in the range tested (1.41-13.42 µg g-1), limits of detection and quantification of 0.42 and 1.28 µg g-1, respectively, low relative standard deviation (3.4%) and recovery ranging from 95 to 103%. The method proved reliable for quantification of lutein added to yogurt.

ESTUDO DA PREPARAÇÃO DOS EXTRATOS DE PRÓPOLIS E SUAS APLICAÇÕES

Ethanolic extracts from propolis were performed by using lhe water and vaflous coneentrations of etanol as solvent. The extracts were investigated by measurement of absorption spectruin with Uv-spectrophotometer (UV-scanning), reversed phase-high performance thin-layer chromatography, Reversed phase-HPLC. Maximum absorption of ali extracts was 290 nm, resembling flavonoid compounds and 80% ethanolic extract showed highest absorption at 290 nm. The most isosakuranetin, quercefin, and kaempferol were extracted from mixtures of propolis and 60% etanol, whereas 70% etanol extracted te most pinocembrin and sakuranetin, but 80% etanol extracted more kaempferide, acacetin, and isorhamnetin from propolis. The 60 to 80% ethanolic extracts ofpropolis inhibited highly to microbial growth and 70 and 80% ethanolic extracts showed lhe greatest antioxidant activity and 80% ethanolic extract inhibited highly to hyaluronidase activity.

TEOR DE CAFEÍNA EM CAFÉS BRASILEIROS

Different brands and batches of brazilian regular and instant coffee were purchased in supermarkets of Campinas? city and analysed for caffeine content. The method used involved extraction with boiling water, clarification with saturated basic acetate and determination by high performance liquid cromatography. Analysis was carried out using a Model 6000 A solvent delivery system (Waters associates), and a Model 7125 sample injector system (Reodyne, Inc.) with a 5µl sample loop. The system was also equipped with a Waters Model M440 absorbance detector set at 254 nm. A Merck ODS 5µm column (15 cm x 4.6 mm i.d.) was used to separate the caffeine. The mobile phase was methanol:water (25:75, v/v). The caffeine content varied for different brands and types of coffee and according to the beverage preparation technique. Values in the range of 0.43 to 0.85 mg/ml and 0.61 to 0.82 mg/ml were determined in regular and instant coffee, respectively.

Confiabilidade da eficiência mastigatória com beads e correlação com a atividade muscular

TEMA: a avaliação da eficiência mastigatória pela análise colorimétrica com beads, pode ser um método promissor, mas não há relatos sobre a sua confiabilidade. OBJETIVO: investigar a confiabiabilidade das beads para teste de eficiência mastigatória e a correlação com a atividade eletromiográfica dos músculos masseter e temporal anterior. MÉTODO: participaram dezenove sujeitos adultos jovens, nove do gênero masculino e dez do feminino com idades entre dezoito e vinte-oito anos, com dentição completa, sem histórico de desordem temporomandibular, trauma, cirurgia na região de cabeça e pescoço, tratamento ortodôntico ou fonoaudiológico. O teste de eficiência mastigatória foi realizado com beads nas condições: mastigação habitual, mastigação unilateral direita e esquerda, com duração de 20 segundos. Simultaneamente, foi realizada a eletromiografia. A atividade em máxima intercuspidação habitual dos dentes também foi registrada. A quantidade de fucsina liberada após a mastigação foi medida usando o espectrofotômetro Beckman DU-7 UV-Visible (Beckman Inc., Palo Alto, CA, USA). RESULTADOS: houve alta confiabilidade do teste de eficiência mastigatória (r = 0,86, p < 0,01) e correlação significante com a atividade eletromiográfica (r = 0,76, p < 0,01). Também houve correlações positivas quando as provas foram analisadas separadamente. CONCLUSÃO: o teste de eficiência mastigatória realizado com beads mostrou-se um método confiável e correlacionado positivamente à atividade eletromiográfica dos músculos temporal anterior e músculos masseter.

Dosimetria esporular: Bacillus subtilis TKJ6312 como biossensor de radiação solar biologicamente ativa

Since 2000, spore dosimetry and spectral photometry have been performed in parallel at the Southern Space Observatory, São Martinho da Serra (Southern Brazil). A comparative study involving data from Punta Arenas - Chile (53.2º S), São Martinho da Serra (29.5º S), Padang - Indonesia (0.9ºS), Brussels - Belgium (50.9º N) and Kiyotake - Japan (31.9º N) from 2000 to 2006 is presented. The Spore Inactivation Doses presented the higher values in summer (973 ± 73 for Punta Arenas and 4,369 ± 202 for São Martinho da Serra, as well 1,402 ± 170 and 3,400 ± 1,674 for Brussels and Kiyotake, respectively). The simplicity, robustness and high resistance of bacterial spores makes the biosensor an potential biological tool for UV-B monitoring.

Modified silicas covalently bounded to 5,10,15,20-tetrakis(2-hydroxy-5-nitrophenyl)porphyrinato iron(III): synthesis, spectroscopic and EPR characterization. Catalytic studies

In this work we have studied cyclooctene epoxidation with PhIO, using a new iron porphyrin, 5,10,15,20-tetrakis(2-hydroxy-5-nitrophenyl)porphyrinato iron(III), supported on silica matrices via eletrostatic interaction and / or covalent bonds as catalyst. These catalysts were obtained and immobilized on the solid supports propyltrimethylammonium silica (SiN+); propyltrimethylammonium and propylimidazole silica [SiN+(IPG)] and chloropropylsilica (CPS) via elestrostatic interactions and covalent binding. Characterization of the supported catalysts by UV-Vis spectroscopy and EPR (Electron paramagnetic resonance) indicated the presence of a mixture of FeII and FeIII species in all of the three obtained catalysts. In the case of (Z)-cyclooctene epoxidation by PhIO the yields observed for cis-epoxycyclooctane were satisfactory for the reactions catalyzed by the three materials (ranging from 68% to 85%). Such results indicate that immobilization of metalloporphyrins onto solid supports via groups localized on the ortho positions of their mesophenyl rings can lead to efficient catalysts for epoxidation reactions. The catalyst 1-CPS is less active than 1-SiN and 1-SiN(IPG), this argues in favour of the immobilization of this metalloporphyrin onto solids via electrostatic interactions, which is easier to achieve and results in more active oxidation catalysts. Interestingly, the activity of the supported catalysts remained the same even after three successive recyclings; therefore, they are stable under the oxidizing conditions.

Study of mural paintings by Fulvio Pennacchi in São Paulo City by mineralogical techniques

The present research deals with two mural paintings made in 1947 with the fresco technique by Fulvio Pennacchi in the Catholic Chapel of the Hospital das Clínicas (São Paulo City, Brazil), namely the Virgin Annunciation and the Supper at Emmaus. This study regards the materials and painting techniques used by the artist, based on historical research,on in situ observations and laboratory analytical techniques (stereomicroscopy,scanning electron microscopy with an energy dispersive spectrometer, X-ray diffractometry, electron microprobe, images obtained with UV-light), aiming to improve the methods of characterization of objects of our cultural heritage, and to enhance its preservation accordingly. The results lead to the identification of the plaster components and of distinct layers in the frescoes, besides further information on grain size, impurities and textures, composition of pigments, and features of deterioration, such as efflorescences. The degree of degradation of the murals painting was assessed by this way. Our data suggest that a single layer of plaster was used by Pennacchi, as a common mortar with fine- and medium-grained aggregates. Differences in texture were obtained by adding gypsum to the plaster.

Electrochemical behavior of parent and photodegradation products of some selected pesticides

Electrochemical behavior of pesticides is extensively studied, but little attention has been given to the study of their degradation products (by-products) by electrochemical methods. However, the degradation products of pesticides can be even more toxic then the parent products and such studies should be encouraged. Therefore, the objective of this work was to evaluate the electroactivity of by-products of imazaquin, methylparathion, bentazon and atrazine, generated by UV irradiation and measured using cyclic and differential pulse voltammetry and UV-visible absorption spectrophotometry. Results have shown that several by-products exhibit electroactivity, allowing, in some cases, the simultaneous determination of both parent and degradation products.

Photo-fenton degradation of poly(Ethyleneglycol)

Polyethyleneglycol (PEG) was photooxidized in a photo-Fenton system and results compared with the dark reaction. The products were analysed using GPC and HPLC. In the absence of light, PEG samples needed 490 min to reduce their w by 50%, whereas under UV irradiation, only 10 min were necessary. The exponential decay of w with a concomitant increase in polydispersity and number of average chain scission, characterized a random chain scission mechanism. The degradation products of PEG in both systems showed the presence of lower molecular weight products, including smaller ethyleneglycols and formic acid. The mechanism involves consecutive processes, were the larger ethyleneglycols give rise, successively, to smaller ones. This suggests that the mechanism involves successive scissions of the polymer chain. Irradiated samples decomposed faster than those kept in the dark This study proves that the foto-Fenton method associated with UV-light is a good reactant for PEG photodegradation.

Adsorção do corante azul de metileno em partículas de argilominerais: análise dos tamanhos das partículas

Interactions of cationic dye methylene blue (MB) with clay particles in aqueous suspension have been extensively studied. As already known, the number of natural negative charges on the clay modifies significantly the particle sizes dispersed in water and therefore the nature of the interaction with the dye. This work evaluated with UV-Vis spectroscopy method how the clay particle sizes weighted on the adsorption and rearrangement of the dye molecules in aqueous system. The results obtained from light-scattering measurements confirmed that larger particles are found in suspensions containing the high-charged clays as the visible absorption band related to the MB aggregates (570 nm) on these suspensions prevailed.

Avaliação de solventes de extração por ultrassom usando-se cromatografia líquida de alta eficiência para a determinação de hidrocarbonetos policíclicos aromáticos em solos contaminados

A method using ultrasonication extraction for the determination of 17 polycyclic aromatic hydrocarbons (PAHs), selected by the USEPA and NIOSH as "consent decree" priority pollutants, in soil by High Performance Liquid Chromatography (HPLC) was studied. Separation and detection were completed in 20 min with a C18 columm, acetonitrile-water gradient elution and ultraviolet absorption and fluorescence detections. The detection limits, for a 10 µL of solution injection, were less than 9,917 ng/g in UV detection and less than 1,866 ng/g in fluorescence detection. Several organic solvents were tested for extraction of the 17 PAHs from soils. Acetone was the best solvent among the three solvents tested, and the order of the extraction efficiencies was: acetone>methanol>acetonitrile. Ultrasonication using acetone as solvent extraction was used to evaluate the biodegradation of those compounds in contaminated soil during a vermicomposting process.

Multivariate analysis of the effects of soil parameters and environmental factors on the flavonoid content of leaves of Passiflora incarnata L., Passifloraceae

The aim of the present study was to evaluate the effect of soil characteristics (pH, macro- and micro-nutrients), environmental factors (temperature, humidity, period of the year and time of day of collection) and meteorological conditions (rain, sun, cloud and cloud/rain) on the flavonoid content of leaves of Passiflora incarnata L., Passifloraceae. The total flavonoid contents of leaf samples harvested from plants cultivated or collected under different conditions were quantified by high-performance liquid chromatography with ultraviolet detection (HPLC-UV/PAD). Chemometric treatment of the data by principal component (PCA) and hierarchic cluster analyses (HCA) showed that the samples did not present a specific classification in relation to the environmental and soil variables studied, and that the environmental variables were not significant in describing the data set. However, the levels of the elements Fe, B and Cu present in the soil showed an inverse correlation with the total flavonoid contents of the leaves of P. incarnata.