Efecto in vivo de diversas antracenonas diméricas sobre peroxisomas de Candida boidinii

Tesis (Maestría en Ciencias con Especialidad en Quimica Analítica Biomédica) UANL

Estudo da distribuição e do potencial de metilação do mercúrio em solos e sedimentos de áreas a serem inundadas para aproveitamento hidrelétrico: Vinicius Marques Gomes. -

Pós-graduação em Química - IQ

Modelagem analítica e experimental da filtração em meios porosos

Deep bed filtration occurs in several industrial and environmental processes like water filtration and soil contamination. In petroleum industry, deep bed filtration occurs near to injection wells during water injection, causing injectivity reduction. It also takes place during well drilling, sand production control, produced water disposal in aquifers, etc. The particle capture in porous media can be caused by different physical mechanisms (size exclusion, electrical forces, bridging, gravity, etc). A statistical model for filtration in porous media is proposed and analytical solutions for suspended and retained particles are derived. The model, which incorporates particle retention probability, is compared with the classical deep bed filtration model allowing a physical interpretation of the filtration coefficients. Comparison of the obtained analytical solutions for the proposed model with the classical model solutions allows concluding that the larger the particle capture probability, the larger the discrepancy between the proposed and the classical models

Filmes de metal-hexacianoferrato: Uma ferramenta em química analítica

Chemically modified electrodes based on hexacyanometalate films are presented as a tool in analytical chemistry. Use of amperometric sensors and/or biosensors based on the metal-hexacyanoferrate films is a tendency. This article reviews some applications of these films for analytical determination of both inorganic (e.g. As3+, S2O3 2-) and organic (e.g. cysteine, hydrazine, ascorbic acid, gluthatione, glucose, etc.) compounds.

Desenvolvimento de metodologia analítica ambientalmente mais amigável para a determinação de ureía em atrizes diversas

Pós-graduação em Química - IQ

Validação de metodologia analítica por CLAE-DAD para determinação de compostos fenólicos e atividade biológica em coprodutos agroindustriais

The southern region of Brazil, especially the states of Parana and Santa Catarina stand out for growing grapes and apples for fresh consumption and in order to add value to these products, process the material for the production of wine, juices and jellies . As a result large quantities of by-products, such as peels, seeds and pulp are produced becoming environmental problems. Studies reuse of these by-products have attracted interest because they have shown a high biological potential, due to the presence of high levels of phenolic compounds, which are associated with a lower incidence of disease caused by oxidative stress, due to its antioxidant, antiinflammatory and antibacterial properties. Currently, few studies are presented on the phenolic composition and biological potential of waste grape variety Bordô (Vitis labrusca) and apple (Malus domestica) Gala variety, cultivated in southern Brazil. Within this context, the objectives of this study were: compare the efficiency of solidliquid and liquid-liquid extraction, perform the optimization and validation of analytical methodology by HPLC-DAD for the separation, identification and quantification of multiclass phenolic compounds, evaluate the activity antioxidant by sequestering methods of free radical 2,2-diphenyl-1 picrilhidrazina (DPPH) and 2,2-azino-bis (3- ethyl-benzthiazoline-6-sulphonic acid) (ABTS) solution, reduction of Fe3+ in Fe2+ method (FRAP), ORAC, RP-HPLC-ABTS online, Rancimat and determination of total phenolics three agro-industrial byproducts, pomace and stems grape Bordô produced in Paraná Southwest region and Gala apple pomace coming from the Santa Catarina West. Optimization and validation of chromatographic method showed satisfactory quality parameters for the compounds of interest and the solidliquid extraction was more efficient in extracting phenolic evaluated. The three byproducts evaluated showed significant levels of phenolic compounds when analyzed by HPLC, especially flavonoids, catechin and epicatechin besides that showed significant antioxidant capacity. The grape stems extract had the highest sequestration capacity of DPPH and ABTS radical and reduced iron, and high content of phenolic compounds. The apple pomace extract showed the best response to the Rancimat method, which indicates a high potential to protect the oil from lipid oxidation, was no significant difference when compared to synthetic antioxidant TBHQ. The results of this study showed that the agro-industrial coproducts analyzed are rich in phenolic compounds of high antioxidant capacity and therefore must be better explored by the food and pharmaceutical industries.

Modelagem analítica e experimental da filtração em meios porosos

Deep bed filtration occurs in several industrial and environmental processes like water filtration and soil contamination. In petroleum industry, deep bed filtration occurs near to injection wells during water injection, causing injectivity reduction. It also takes place during well drilling, sand production control, produced water disposal in aquifers, etc. The particle capture in porous media can be caused by different physical mechanisms (size exclusion, electrical forces, bridging, gravity, etc). A statistical model for filtration in porous media is proposed and analytical solutions for suspended and retained particles are derived. The model, which incorporates particle retention probability, is compared with the classical deep bed filtration model allowing a physical interpretation of the filtration coefficients. Comparison of the obtained analytical solutions for the proposed model with the classical model solutions allows concluding that the larger the particle capture probability, the larger the discrepancy between the proposed and the classical models

Polímeros biomiméticos em química analítica. Parte 1: preparo e aplicações de MIP (Molecularly Imprinted Polymers) em técnicas de extração e separação

MIPs are synthetic polymers that are used as biomimetic materials simulating the mechanism verified in natural entities such as antibodies and enzymes. Although MIPs have been successfully used as an outstanding tool for enhancing the selectivity or different analytical approaches, such as separation science and electrochemical and optical sensors, several parameters must be optimized during their synthesis. Therefore, the state-of-the-art of MIP production as well as the different polymerization methods are discussed. The potential selectivity of MIPs in the extraction and separation techniques focusing mainly on environmental, clinical and pharmaceutical samples as applications for analytical purposes is presented.

Polímeros biomiméticos em química analítica. Parte 2: aplicações de MIP (Molecularly Imprinted Polymers) no desenvolvimento de sensores químicos

The aim of this paper is the description of the strategies and advances in the use of MIP in the development of chemical sensors. MIP has been considered an emerging technology, which allows the synthesis of materials that can mimic some highly specific natural receptors such as antibodies and enzymes. In recent years a great number of publications have demonstrated a growth in their use as sensing phases in the construction of sensors . Thus, the MIP technology became very attractive as a promising analytical tool for the development of sensors.

A importância da Química Analítica Qualitativa nos cursos de Química das instituições de ensino superior brasileiras

The results of a survey of institutions offering undergraduate studies, with the objective of evaluating the importance of Qualitative Analytical Chemistry for Chemistry courses in Brazil, are presented and discussed. Judging by the data, the content of the course of Qualitative Analytical Chemistry is considered by the Brazilian institutions offering undergraduate studies to be a body of knowledge essential for the formation of the chemist. This aspect is deemed valid for both baccalaureate and teaching license studies.

Metodologia analítica para determinação de folatos e ácido fólico em alimentos

The aim of this work was to develop and to validate a methodology using HPLC for the simultaneous determination of folates and folic acid in foods. The limits of detection and the recovery rates for the vitamins in the certified reference materials were respectively 5 pg/mL and 94-108% for 5-MTHF, 7 pg/mL and 97-102% for THF, 30 pg/mL and 97.9-104% for 5-FTHF, 30 pg/mL and 95-107 for 10-FFA, 5 ng/mL and 97-102% for FA and 5 ng/mL and 98-103% for 10-MFA. Repeatability showed a coefficient of variation below 3.9% for all the vitamins. The proposed methodology was shown to be efficient when applied to different certified reference materials, namely pig's liver (BCR487), powdered milk (BCR421) and a vegetable mixture (BCR485).

Química Analítica de Processos

Process Analytical Chemistry (PAC) is an important and growing area in analytical chemistry, that has received little attention in academic centers devoted to the gathering of knowledge and to optimization of chemical processes. PAC is an area devoted to optimization and knowledge acquisition of chemical processes, to reducing costs and wastes and to making an important contribution to sustainable development. The main aim of this review is to present to the Brazilian community the development and state of the art of PAC, discussing concepts, analytical techniques currently employed in the industry and some applications.

Experimento didático sobre cromatografia gasosa: uma abordagem analítica e ambiental

This paper describes an experiment to teach the principles of gas chromatography exploring the boiling points and polarities to explain the elution order of a series of alcohols, benzene and n-propanone, as well as to teach the response factor concept and the internal standard addition method. Retention times and response factors are used for qualitative identification and quantitative analysis of a hypothetical contamination source in a simulated water sample. The internal standard n-propanol is further used for quantification of benzene and n-butanol in the water sample. This experiment has been taught in the instrumental analysis course offered to chemistry and oceanography students.

Aproximação numérica – analítica para a modelagem da conversão termoquímica de combustíveis sólidos

Um algoritmo numérico foi criado para apresentar a solução da conversão termoquímica de um combustível sólido. O mesmo foi criado de forma a ser flexível e dependente do mecanismo de reação a ser representado. Para tanto, um sistema das equações características desse tipo de problema foi resolvido através de um método iterativo unido a matemática simbólica. Em função de não linearidades nas equações e por se tratar de pequenas partículas, será aplicado o método de Newton para reduzir o sistema de equações diferenciais parciais (EDP’s) para um sistema de equações diferenciais ordinárias (EDO’s). Tal processo redução é baseado na união desse método iterativo à diferenciação numérica, pois consegue incorporar nas EDO’s resultantes funções analíticas. O modelo reduzido será solucionado numericamente usando-se a técnica do gradiente bi-conjugado (BCG). Tal modelo promete ter taxa de convergência alta, se utilizando de um número baixo de iterações, além de apresentar alta velocidade na apresentação das soluções do novo sistema linear gerado. Além disso, o algoritmo se mostra independente do tamanho da malha constituidora. Para a validação, a massa normalizada será calculada e comparada com valores experimentais de termogravimetria encontrados na literatura, , e um teste com um mecanismo simplificado de reação será realizado.