The contributions of SBQ for the graduate programs in chemistry

Brazilian Chemical Society (SBQ) enjoys 30 years dedicating to the development, consolidation and divulgation of research in the Chemistry area. There are graduate programs in chemistry spread through all Brazilian regions and different actions related to them have been supported by SBQ since its foundation. The chemistry divisions, the Annual Meeting, the journals Quimica Nova, JBCS and QNEsc as well as the Graduate Forum offer an opportunity to discuss and to divulge Chemistry in the present context but also its evolution considering the men and the environmental needs leading to the development of new methodologies for different parts of the society. This manuscript describes the importance and the contribution of SBQ to the development of graduate curses of Chemistry in Brazil.3061435143

Six weeks of conditioning exercise increases total, but not free testosterone in lifelong sedentary aging men

Introduction: Advancing age is associated with a gradual decline in circulating androgens, and the putative role of exercise training on systemic androgens remains to be adequately defined. Methods: The present investigation examined the impact of 6 weeks of supervised exercise training on resting levels of systemic hormones in a cohort of lifelong sedentary men [SED (n = 28), 62.5 ± 5.3 years], compared with a positive control group of age-matched lifelong exercisers [LE (n = 20), 60.4 ± 4.7 years, >30 years training history]. Blood hormones were sampled pre- and post-intervention from an antecubital forearm vein and analysed using electrochemiluminescent immunoassay. Cardiorespiratory fitness () was determined via indirect calorimetry during an incremental cycle test to volitional exhaustion. Results: Analysis of variance (ANOVA) revealed a lack of significant change in any parameter amongst LE, whilst SED experienced a significant exercise-induced improvement in cardiorespiratory fitness and total testosterone (all p  0.05) amongst SED. Conclusions: Although resting levels of systemic total testosterone increased in response to 6 weeks of exercise training, increases in SHBG negated any potential relationship between calculated-free or bioavailable testosterone. These findings indicate that increases in bioavailable testosterone fraction are not required for cardiorespiratory fitness improvements in aging men

Determination of selenium in some food matrices by electrothermal atomic absorption spectrometry after preconcentration with diethyldithiophosphate

Selenium preconcentration for its electrothermal atomic absorption spectrometric determination in biological tissues, such as food samples, is described. The method is applicable to matrices containing 0.05-1 mg kg(-1) Se, like fish, meat, and flour. After a closed nitric acid digestion procedure, an aliquot of the sample is diluted with 0.2% v/v HNO3, diethyldithiophosphate solution is added and the complex formed is loaded on a minicolumn containing 30 mg of SiO2-C-18, using a peristaltic pump. The complex, eluted with ethanol, is collected into a cuvette for the determination of selenium. A calibration curve is made from selenium(IV) solutions, prepared in 0.2% v/v HNO3. In order to minimize diethyldithiophosphate interference, a chemical modifier is used, chosen after comparison among Rh, Pd, Ir and Ni, and Rh proved to be the best. The furnace program can include a pyrolysis step at 1000degreesC or, alternatively, omit it, skipping from a drying step to the atomization. A typical analytical curve goes up to 4 ng mL(-1) Se. An enrichment factor of 65 is possible, taking 6 min for each preconcentration step. Good results were obtained for several certified reference materials. The entire procedure, including the digestion, can proceed rapidly, because there is no need for a pre-reduction step, coprecipitation or a lengthy solvent extraction.18778378

A quartz tube atomizer with tungsten coil: a new system for vapor atomization in atomic absorption spectrometry

A quartz tube atomizer with a tungsten coil (QTAW) is described for the determination of arsenic in a flow injection hydride generation system. The flow injection system includes a Nafion(R) membrane that continuously dries the gaseous species, allowing removal of 4.2 mg min(-1) of water, corresponding to an efficiency of 92.7%. The application of this system to the determination of arsenic, using the optimized conditions, shows considerable stability with time, without loss of sensitivity, and it was possible to obtain a calibration curve with a wide range (up to 500 mg l(-1)), with R-2 = 0.9998, a limit of detection of 1.5 mg l(-1) and an analytical frequency of 60 determinations per hour. The determination of arsenic in samples of mineral and sea-waters, sediment and biological materials, shows good accuracy and precision between the results obtained and the certified values for the recovery of arsenic, with RSD values less than 6%.17111516152

Evaluation of direct analysis for trace elements in tea and herbal beverages by ICP-MS

In general, inductively coupled plasma mass spectrometry (ICP-MS) food analysis requires numerous sample treatment steps that imply an increase of analysis time and the use of chemicals. In this study, the main objective was to evaluate the applicability of the direct analysis by ICP-MS to determine twelve elements (Al, As, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se and Zn) in tea and herbal beverages. Direct analysis method was compared with two other sample treatments: minimum treatment (acid dilution) and using a destructive method (microwave assisted digestion). Besides the lowest time of analysis, direct analysis provides a reliable response and agrees with the “green chemistry” principles. High sensitivity was also observed by low values of limits of detection and quantification, in general, below 2.5 µg L-1. The method accuracy was evaluated by spiked experiments and values ranged between 82 and 120%. Low values of coefficient of variation were also observed, 2 to 17%, for all analytes. The method exhibited applicability for commercial tea samples as well as for drinks made by herb infusion26612111217CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informaçãosem informação2012/19142-

A Phase II, Randomized, Double-Blind, Placebo Controlled, Dose-Response Trial of the Melatonin Effect on the Pain Threshold of Healthy Subjects

Background: Previous studies have suggested that melatonin may produce antinociception through peripheral and central mechanisms. Based on the preliminary encouraging results of studies of the effects of melatonin on pain modulation, the important question has been raised of whether there is a dose relationship in humans of melatonin on pain modulation. Objective: The objective was to evaluate the analgesic dose response of the effects of melatonin on pressure and heat pain threshold and tolerance and the sedative effects. Methods: Sixty-one healthy subjects aged 19 to 47 y were randomized into one of four groups: placebo, 0.05 mg/kg sublingual melatonin, 0.15 mg/kg sublingual melatonin or 0.25 mg/kg sublingual melatonin. We determine the pressure pain threshold (PPT) and the pressure pain tolerance (PPTo). Quantitative sensory testing (QST) was used to measure the heat pain threshold (HPT) and the heat pain tolerance (HPTo). Sedation was assessed with a visual analogue scale and bispectral analysis. Results: Serum plasma melatonin levels were directly proportional to the melatonin doses given to each subject. We observed a significant effect associated with dose group. Post hoc analysis indicated significant differences between the placebo vs. the intermediate (0.15 mg/kg) and the highest (0.25 mg/kg) melatonin doses for all pain threshold and sedation level tests. A linear regression model indicated a significant association between the serum melatonin concentrations and changes in pain threshold and pain tolerance (R2 = 0.492 for HPT, R2 = 0.538 for PPT, R2 = 0.558 for HPTo and R2 = 0.584 for PPTo). Conclusions: The present data indicate that sublingual melatonin exerts well-defined dose-dependent antinociceptive activity. There is a correlation between the plasma melatonin drug concentration and acute changes in the pain threshold. These results provide additional support for the investigation of melatonin as an analgesic agent. Brazilian Clinical Trials Registry (ReBec): (U1111-1123-5109). IRB: Research Ethics Committee at the Hospital de Clínicas de Porto Alegre

Acid decomposition of yerba mate (ilex paraguariensis) using a reflux system for the evaluation of Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Pb and Zn contents by atomic spectrometric techniques

In the first part of this paper, two acid decomposition procedures for the determination of Al, Ca, Fe, Mg, Mn and Zn contents in yerba mate samples by inductively coupled plasma optical emission spectrometry (ICP OES) were compared. Using a reflux system, the samples were treated with a mixture of HNO3 and H2O2 for 3 hours at 220 °C in the digester block. The results from five commercial yerba mate samples were compared with the results obtained from microwave digestion. Good agreement between the procedures at a 95% confidence level was obtained with relative standard deviation (RSD) values lower than 10.0%. The accuracy was evaluated using addition and recovery experiments (80.5 to 112.8%). In the second part, Ca, Cd, Cr, Cu, Fe, K, Mg, Na, Pb and Zn concentrations were evaluated in the yerba mate infusion. The results showed that elements such as Na, K, Mg and Zn are easily transferred to the hot water used for the infusion. For Pb and Cd, the concentrations found in the analyzed samples were lower than the values established by Brazilian legislation274685693CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DO RIO GRANDE DO SUL - FAPERGSSem informação552197/2011-4Sem informaçã

Classification of processed and natural coconut water using HCA, PCA and metallic ion levels obtained by Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES).

Inductively Coupled Plasma Optical Emission Spectrometry was used to determine Ca, Mg, Mn, Fe, Zn and Cu in samples of processed and natural coconut water. The sample preparation consisted in a filtration step followed by a dilution. The analysis was made employing optimized instrumental parameters and the results were evaluated using methods of Pattern Recognition. The data showed common concentration values for the analytes present in processed and natural samples. Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) indicated that the samples of different kinds were statistically different when the concentrations of all the analytes were considered simultaneously.29465465