Uso de hardware de código fonte aberto "Arduino" para acionamento de dispositivo solenoide em sistemas de análises em fluxo

This paper describes the use of the open source hardware platform, denominated "Arduino", for controlling solenoid valves for solutions handling in flow analysis systems. System assessment was carried out by spectrophotometric determination of iron (II) in natural water. The sampling rate was estimated as 45 determinations per hour and the coefficient of variation was lower than 3%. Per determination, 208 µg of 1-10-phenanthroline and ascorbic acid were consumed, generating 1.3 mL of waste. "Arduino" proved a reliable microcontroller with low cost and simple interfacing, allowing USB communication for solenoid device switching in flow systems.

Síntese do material mesoporoso MCM-41 usando esponja de água-doce como fonte de sílica

Fresh water sponge was used as a silica source for the synthesis of MCM-41 via the hydrothermal process. The silica was extracted from the sponge by washing with nitric acid and piranha solution. Synthesis of MCM-41 was performed at 100 °C for 5 days and the procedure was optimized, with modifications made to the leaching temperature of the silica and the synthesis of mesoporous material, which was characterized by XRD, FT-IR, SEM and adsorption of N2. The optimal result was achieved at a temperature of 135 °C for 3 days, showing ordered mesoporous material with a surface area of 1080 m² g-1.

Carboidratos como fonte de compostos para a indústria de química fina

Coal, oil, natural gas, and shale gas are biomass that is formed millions of years ago. These are non-renewable and depleting, even considering the recent discovery of new sources of oil in the presalt and new technologies for the exploitation of shale deposits. Currently, these raw materials are used as a source of energy production and are also important for the production of fine chemicals. Since these materials are finite and their (oil) price is increasing, it is clear that there will be a progressive increase in the chemical industry to use renewable raw materials as a source of energy, an inevitable necessity for humanity. The major challenge for the society in the twenty first century is to unite governments, universities, research centers, and corporations to jointly act in all areas of science with one goal of finding a solution to global problems, such as conversion of biomass into compounds for the fine chemical industry.Non-renewable raw materials are used in the preparation of fuels, chemical intermediates, and derivatives for the fine chemical industry. However, their stock in nature has a finite duration, and their price is high and will likely increase with their depletion. In this scenario, the alternative is to use renewable biomass as a replacement for petrochemicals in the production of fine chemicals. As the production of biomass-based carbohydrates is the most abundant in nature, it is judicious to develop technologies for the generation of chain products (fuels, chemical intermediates, and derivatives for the fine chemicals industry) using this raw material. This paper presents some aspects and opportunities in the area of carbohydrate chemistry toward the generation of compounds for the fine chemical industry.

Cromatografia gasosa-espectrometria de massas e derivatização assistida por micro-ondas na identificação de isômeros de glicose: uma prática para o ensino avançado em análise e caracterização de compostos orgânicos

This work reports a practical case based on the use of microwave-assisted derivatization and GC-MS for the analysis of glucose. Using two different methods for derivatization, one reference compound and the calculated dipole moment, all the isomers of glucose were identified. Identification was corroborated for the assignment of structures using the mass spectra. With this work, students are expected to associate different types of information to solve the complex problem of the analysis of glucose.

Cinética e caracterização de ramnolipídeos produzidos por Pseudomonas aeruginosa MSIC02 utilizando glicerol como fonte de carbono

Glycerol, a co-product of biodiesel production, was used as a carbon source for the kinetics studies and production of biosurfactants by P. aeruginosa MSIC02. The highest fermentative parameters (Y PX = 3.04 g g-1; Y PS = 0.189 g g-1, P B = 31.94 mg L-1 h-1 and P X = 10.5 mg L-1 h-1) were obtained at concentrations of 0.4% (w/v) NaNO3 and 2% (w/v) glycerol. The rhamnolipid exhibited 80% of emulsification on kerosene, surface tension of 32.5 mN m-1, CMC = 28.2 mg L-1, C20 (concentration of surfactant in the bulk phase that produces a reduction of 20 dyn/cm in the surface tension of the solvent) = 0.99 mg L-1, Γm (surface concentration excess) = 2.4 x 10-26 mol Å-2 and S (surface area) = 70.4 Ų molecule-1 with solutions containing 10% NaCl. A mathematical model based on logistic equation was considered to representing the process. Model parameters were estimated by non-linear regression method. This approach was able to give a good description of the process.

Zingiber officinale (GENGIBRE) COMO FONTE ENZIMÁTICA NA REDUÇÃO DE COMPOSTOS CARBONÍLICOS

Various vegetables as biological catalysts were evaluated in enantioselective reduction of carbonyl compounds. The stereoselectivity of the process was in agreement with Prelog's rule for twelve of the vegetables, whereas okra and green peppers formed anti-Prelog products. Zingiber officinale exhibited the best results with 30% conversion and 89% ee. The parameters of the reaction such as time, solvent and other substrates investigated, as well as the specie, showed good chemo- and enantioselectivity.

EXTRAÇÃO ASSISTIDA POR ULTRASSOM PARA DETERMINAÇÃO COLORIMÉTRICA DE FERRO EM SOLO: UMA COMPARAÇÃO COM ESPECTROMETRIA DE MASSA COM PLASMA INDUTIVAMENTE ACOPLADO

A simple procedure for ultrasound-assisted extraction and colorimetric determination of iron in soil samples was developed. The iron concentration in the analyzed samples was determined by the colorimetric method and the results compared with inductively coupled plasma mass spectrometry (ICP-MS). Fifteen soil samples were analyzed and the iron concentration results compared with those obtained by ICP-MS using microwave-assisted sample digestion. The proposed procedure showed good efficiency for iron extraction and the results obtained by colorimetric determination exhibited good agreement with ICP-MS. Moreover, ultrasound-assisted extraction and colorimetric determination is a simple, fast and low-cost procedure for application in routine analysis.

DETERMINAÇÃO ESPECTROFOTOMÉTRICA DE METILDOPA EM ENSAIO DE DISSOLUÇÃO DE COMPRIMIDOS UTILIZANDO EXTRATO DE RABANETE COMO FONTE DE PEROXIDASE

An enzymatic spectrophotometric method for the determination of methyldopa in a dissolution test of tablets was developed using peroxidase from radish (Raphanus sativus). The enzyme was extracted from radish roots using a phosphate buffer of pH 6.5 and partially purified through centrifugation. The supernatant was used as a source of peroxidase. The methyldopachrome resulting from the oxidation of methyldopa catalyzed by peroxidase was monitored at 480 nm. The enzymatic activity was stable for a period of at least 25 days when the extract was stored at 4 or -20 ºC. The method was validated according to RDC 899 and ICH guidelines. The calibration graph was linear in the range 200-800 µg mL-1, with a correlation coefficient of 0.9992. The limits of detection and quantification in the dissolution medium were 36 and 120 µg mL-1, respectively. Recovery was greater than 98.9%. This method can be applied for the determination of methyldopa in dissolution tests of tablets without interference from the excipients.

SÍNTESE DE DERIVADOS DE FENANTRIDINONAS POR ARILAÇÃO DIRETA. CARACTERIZAÇÃO DOS ESPECTROS DE ABSORÇÃO E EMISSÃO DE EXEMPLOS REPRESENTATIVOS

The phenanthridinone heterocyclic system has attracted considerable attention in recent years due to the diverse array of physical, chemical and pharmacological properties demonstrated by natural and synthetic derivatives. As a consequence there has been considerable development of synthetic methodology for the synthesis of this and related heterocyclic ring systems. The synthetic literature is discussed and is compared with a direct arylation methodology for the intramolecular cyclization of tertiary (2-iodo)benzoylamides to generate the biaryl bond of these compounds. The efficient methodology allowed the synthesis of a number of previously unknown phenanthridinone products. The photoluminescent properties of representative examples were characterized and it is proposed that the previously unknown compound 1s reveals dual fluorescence in a manner similar to the known compound 1r.