The vast majority of chemical reactions occurs only in the ground state, however photochemical reactions like chemiluminescence take place in ground and excited states. In almost all chemiluminescence processes oxygen-oxygen bond breakage is involved. But, there is no general reason to explain why these processes occur via an oxygen-oxygen cleavage. These types of phenomena are usually highly exothermic. Computational chemistry has risen as a powerful tool to characterize and analyze chemical phenomena. Quantum mechanics are utilized to explain chemical observations. Applying these equations, one can compute the chemical properties of any system in any state. In the present study, three chemiluminescence reactions derived from luminol are modeled; nitrogen based, oxygen based and dianion nitrogen based models. The key factor of oxygen-oxygen bond rupture is discussed and rationalized. The electronic potential energy surfaces of the three compounds are computed at complete active space self-consistent field theory. Peroxide compounds compared to the dinitrogenated  compounds show a lower activation energy and they are more exothermic. This study allows us to rationalize why luminol needs to be presented in a basic medium and oxidized in order to produce chemiluminescence.

No description available.

Ultrasonic descalers are used in dentistry to remove calculus and other contaminants from teeth. One mechanism which may assist in the cleaning is cavitation generated in cooling water around the descaler. The spatial distribution of cavitation around three designs of descaler tips and under three load conditions has been observed using sonochemiluminescence from a luminol solution and compared with the vibratory motion of the tips in a water bath, characterised by scanning laser vibrometry. The type of cavitation was confirmed by acoustic emission analysed by a ‘Cavimeter’ supplied by NPL. Surface profilometry and SEM of eroded hydroxyapatite pellets was performed to quantitatively study the erosion caused by a descaler tip in both contact and non-contact modes. Densitometry was used to study the erosion of black ink from a glass microscope slide, and determined that under the majority of conditions, no erosion was demonstrated via cavitation, by descalers operating in non-contact mode, although significant erosion was demonstrated with the tip in contact with the slide.

Made available in DSpace on 2016-08-10T10:38:45Z (GMT). No. of bitstreams: 1 LUCIANA MAIA ESCHER DOS SANTOS.pdf: 3201320 bytes, checksum: f5c8c078f60bbba17912e8c39742ed0a (MD5) Previous issue date: 2013-06-24 / Molecular Biology shown to be an effective tool in forensic laboratories for the ability to identify an individual from minute amounts of biological samples such as blood, bones, semen, hair, teeth, nails, spittle, urine and other biological fluids recovered from the crime scene. One of the main biological evidence found at a crime scene are traces of bloodstains. This study aimed to analyze the molecular profiles of biological samples exposed to the chemiluminescent reagent luminol based on different storage times (48 hours and 30 days). With the measurement of all samples can be inferred that in the first 48 hours of storage, there was obtained DNA and varying concentrations after application of the chemiluminescent reagent. The samples were amplified by PCR using a multiplex system AmpFlSTR ® Select NGM and capillary electrophoresis. Molecular profiles were obtained complete and incomplete denoting specificity as the quality and quantity of the sample analyzed. The selection of molecular markers mini-STRs greatly contributed to the success of these profiles, allowing the study and analysis of degraded material. Our data suggest that the degradation of the DNA molecule exposed to the chemiluminescent reagent was higher in the samples compared to those containing diluted whole blood impregnation. Therefore, analyzing the bloodstains samples exposed to luminol in shorter storage provide molecular profiles compatible to clash samples. / A Biologia Molecular mostrou-se uma ferramenta efetiva nos laboratórios forenses pela capacidade de identificar um indivíduo a partir de quantidades ínfimas de amostras biológicas como sangue, ossos, sêmen, cabelo, dentes, unhas, saliva, urina, entre outros fluidos biológicos recuperados no local do crime. Uma das principais evidências biológicas encontradas em local de crime são vestígios de substâncias hematóides. Esta pesquisa visou a análise de perfis moleculares de amostras biológicas expostas ao reagente quimioluminescente a base de luminol em diferentes tempos de armazenamento (48 horas e 30 dias). Com a quantificação de todas as amostras pode-se inferir que nas primeiras 48 horas de armazenamento, obtiveram-se concentrações variáveis de DNA e após a aplicação do reagente quimioluminescente. As amostras foram amplificadas por PCR utilizando um sistema multiplex AmpFlSTR® NGM SElect e eletroforese capilar. Foram obtidos perfis moleculares completos e incompletos denotando inespecificidade conforme a qualidade e quantidade da amostra analisada. A seleção dos 17 marcadores moleculares mini-STRs em muito contribuiu para o sucesso desses perfis, permitindo estudo e análise de material degradado. Os dados indicam que a degradação da molécula de DNA exposta ao reagente quimioluminescente foi maior nas amostras diluídas em relação àquelas contendo impregnação com sangue total. A análise estatística das amostras com e sem exposição ao reagente quimioluminescente comparado ao grupo controle e em diferentes concentrações, mostrou não haver diferença estatísticamente significativa entre os valores quantificados obtidos. Ainda assim, analisar as amostras hematóides expostas ao luminol em menor tempo de armazenamento proporcionarão perfis moleculares compatíveis ao confronto de amostras.

Os organismos vivos estão expostos à ação oxidativa de espécies reativas de oxigênio (ERO), causando uma série de doenças degenerativas como câncer, aterosclerose, diabetes, artrite e doenças do coração. Estudos têm demonstrado que o consumo de substâncias antioxidantes na dieta diária podem prevenir estes processos oxidativos que provocam o envelhecimento precoce do organismo. Nas últimas décadas tem se destacado o interesse em encontrar antioxidantes naturais para o emprego em produtos alimentícios ou farmacêuticos, com a finalidade de substituir antioxidantes sintéticos, os quais apresentam restrições devido ao seu potencial tóxico. Nesse trabalho, são comparados os resultados de medidas da capacidade antirradicalar de vários derivados fenólicos incluindo produtos naturais obtidos com os ensaios utilizando o radical estável DPPH• e o cátion radical ABTS•+, que apresentam vantagens em relação à simplicidade do método analítico e facilidade na coleta de dados, além da reprodutibilidade dos resultados. Além disso, desenvolveu-se um ensaio com DPPH• para avaliar a capacidade antirradicalar de compostos fenólicos em meio ácido, hidroalcoólico e tamponado, para possibilitar a obtenção de valores da capacidade antirradicalar de flavonoides e compostos análogos em meio aquoso em diferentes estados de ionização. Também, foi utilizado o ensaio quimiluminescente com luminol/hemina/H2O2, desenvolvido pelo nosso grupo de pesquisa, para a determinação da capacidade antirradicalar de extratos, fases e frações de Baccharis regnelli e proposto o novo parâmetro \"Porcentagem de Trolox\" para expressar adequadamente esta capacidade em misturas complexas. A sensibilidade do ensaio luminol comprovou ser maior que a de outros métodos e adequado para medir a capacidade antirradicalar de misturas complexas de produtos naturais, auxiliando no isolamento de novas substâncias com atividade antirradicalar. / Living organisms are exposed to the oxidative action of reactive oxygen species (ROS), causing a series of degenerative diseases such as cancer, atherosclerosis, diabetes, arthritis and heart disease. Studies have shown that consumption of antioxidant substances in the daily diet can prevent these oxidative processes that cause premature aging of the organism. Much attention has been paid in the last decades on the discovery of new natural antioxidants for its use in food or pharmaceutical industry, with the aim of replace synthetic antioxidants, which have restrictions due to their toxic potential. In this study, we compared the results from antiradical capacity determinations of several phenolic derivatives including natural products obtained by two different assays. One of them utilizes the stable radical DPPH• and the other the radical cation ABTS•+ as reagents and both have the advantage of a simple analytical method and ease in data collection as well as high data reproducibility. Furthermore, we have developed a method with DPPH• for the evaluation of the antirradicalar capacity of phenolic compounds in acid and buffered hydroalcoholic media, in order to facilitate the determination of the antiradical capacity of flavonoids and similar compounds in aqueous ambient and to allow differentiation between the capacity of different ionization states of these derivatives. Finally the chemiluminescent luminol/hemin/H2O2 assay, developed by our research group, has been utilized for the determination of the antiradical capacity of extracts, phases and fractions of Baccharis regnelli and the new parameter \"Trolox Percentage\" is being proposed to adequately express the antiradical capacity of complex mixtures. The sensibility of the luminol assay has been found to be higher than that of other methods and is shown to be suitable for the determination of antiradical activity parameters of complex natural product mixtures, contributing to the isolation of new substances with antiradical activity.

Os organismos vivos estão expostos à ação oxidativa de espécies reativas de oxigênio (ERO), causando uma série de doenças degenerativas como câncer, aterosclerose, diabetes, artrite e doenças do coração. Estudos têm demonstrado que o consumo de substâncias antioxidantes na dieta diária podem prevenir estes processos oxidativos que provocam o envelhecimento precoce do organismo. Nas últimas décadas tem se destacado o interesse em encontrar antioxidantes naturais para o emprego em produtos alimentícios ou farmacêuticos, com a finalidade de substituir antioxidantes sintéticos, os quais apresentam restrições devido ao seu potencial tóxico. Nesse trabalho, são comparados os resultados de medidas da capacidade antirradicalar de vários derivados fenólicos incluindo produtos naturais obtidos com os ensaios utilizando o radical estável DPPH• e o cátion radical ABTS•+, que apresentam vantagens em relação à simplicidade do método analítico e facilidade na coleta de dados, além da reprodutibilidade dos resultados. Além disso, desenvolveu-se um ensaio com DPPH• para avaliar a capacidade antirradicalar de compostos fenólicos em meio ácido, hidroalcoólico e tamponado, para possibilitar a obtenção de valores da capacidade antirradicalar de flavonoides e compostos análogos em meio aquoso em diferentes estados de ionização. Também, foi utilizado o ensaio quimiluminescente com luminol/hemina/H2O2, desenvolvido pelo nosso grupo de pesquisa, para a determinação da capacidade antirradicalar de extratos, fases e frações de Baccharis regnelli e proposto o novo parâmetro \"Porcentagem de Trolox\" para expressar adequadamente esta capacidade em misturas complexas. A sensibilidade do ensaio luminol comprovou ser maior que a de outros métodos e adequado para medir a capacidade antirradicalar de misturas complexas de produtos naturais, auxiliando no isolamento de novas substâncias com atividade antirradicalar. / Living organisms are exposed to the oxidative action of reactive oxygen species (ROS), causing a series of degenerative diseases such as cancer, atherosclerosis, diabetes, arthritis and heart disease. Studies have shown that consumption of antioxidant substances in the daily diet can prevent these oxidative processes that cause premature aging of the organism. Much attention has been paid in the last decades on the discovery of new natural antioxidants for its use in food or pharmaceutical industry, with the aim of replace synthetic antioxidants, which have restrictions due to their toxic potential. In this study, we compared the results from antiradical capacity determinations of several phenolic derivatives including natural products obtained by two different assays. One of them utilizes the stable radical DPPH• and the other the radical cation ABTS•+ as reagents and both have the advantage of a simple analytical method and ease in data collection as well as high data reproducibility. Furthermore, we have developed a method with DPPH• for the evaluation of the antirradicalar capacity of phenolic compounds in acid and buffered hydroalcoholic media, in order to facilitate the determination of the antiradical capacity of flavonoids and similar compounds in aqueous ambient and to allow differentiation between the capacity of different ionization states of these derivatives. Finally the chemiluminescent luminol/hemin/H2O2 assay, developed by our research group, has been utilized for the determination of the antiradical capacity of extracts, phases and fractions of Baccharis regnelli and the new parameter \"Trolox Percentage\" is being proposed to adequately express the antiradical capacity of complex mixtures. The sensibility of the luminol assay has been found to be higher than that of other methods and is shown to be suitable for the determination of antiradical activity parameters of complex natural product mixtures, contributing to the isolation of new substances with antiradical activity.

ABSTRACT A GLOW IN THE DARK: SYNTHESIS AND ELECTROPOLYMERIZATION OF CHEMILUMINESCENT THIOPHENE DERIVATIVES Asil, Demet M.Sc., Department of Chemistry Supervisor : Prof. Dr. Ahmet M. &Ouml / nal Co-Supervisor: Assist. Prof. Dr. Atilla Cihaner September 2008, 63 Pages Two novel chemiluminescent monomers, 2,3-dihydrothieno(3,4-d)pyridazine-1,4-dione (T-Lum) and 5,7-di-thiophen-2-yl-2,3-dihydro-thieno[3,4-d]pyridazine-1,4-dione (TTT-Lum), were synthesized. The reaction between T-Lum and TTT-Lum in alkaline solution with H2O2 gave chemiluminescence which can be catalyzed using Fe(III) ion. Owing to its sensitivitiy towards Fe(III) ion / T-Lum and TTT-Lum can be promising materials to detect bloodstains in the application of forensic science instead of luminol which gave response to a large family of metallic cations beside Fe(III). Also, TTT-Lum, which is based on a terthienyl system, was electropolymerized and its corresponding polymer (PTTT-Lum) was obtained via repetitive cycling or constant potential electrolysis in both 0.1 M LiClO4 dissolved in acetonitrile containing 5% of BF3-Et2O by volume and neat BF3- Et2O solution. In addition, PTTT-Lum, soluble in alkaline water, was synthesized successfully without breaking the pyridazinedione unit (chemiluminescent unit), as proved by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Electrochemical Luminescence (ECL) measurements. Thus, PTTT-Lum, bearing chemiluminescent unit, can be a good candidate to be used as a sensor in near future. Furthermore, the PTTT-Lum film has a very stable and well-defined reversible redox couple as well as electrochromic behavior during p-doping process. The polymer film has also a band gap of 1.74 eV with an absorption band in its neutral state at 536 nm. Finally, PTTT-Lum film was found to be electrochemiluminescence active, maintaining its activitiy over 1000 cycles.

Dissertação (mestrado)—Universidade de Brasília, Instituto de Química, Programa de Pós-Graduação em Química, 2013. / Submitted by Alaíde Gonçalves dos Santos (alaide@unb.br) on 2014-04-16T14:17:54Z No. of bitstreams: 1 2013_ThiagoRosaSampaio.pdf: 3870939 bytes, checksum: ba87f9498e0c64094f58b9c8e74aad48 (MD5) / Approved for entry into archive by Guimaraes Jacqueline(jacqueline.guimaraes@bce.unb.br) on 2014-07-16T16:03:54Z (GMT) No. of bitstreams: 1 2013_ThiagoRosaSampaio.pdf: 3870939 bytes, checksum: ba87f9498e0c64094f58b9c8e74aad48 (MD5) / Made available in DSpace on 2014-07-16T16:03:54Z (GMT). No. of bitstreams: 1 2013_ThiagoRosaSampaio.pdf: 3870939 bytes, checksum: ba87f9498e0c64094f58b9c8e74aad48 (MD5) / Este trabalho descreve o desenvolvimento e avaliação de microssistemas de análise por injeção em fluxo à base de Uretana-Acrilato com célula de detecção por quimiluminescência integrada. A fotolitografia profunda no ultravioleta foi empregada para gravar os canais (largura de 500 μm e profundidade de 440 μm, aproximadamente) em fotoresiste de Uretana-Acrilato (UA), sendo a célula de detecção, em formato de serpentina ou caracol, desenvolvida com diâmetro de 1,0 cm, tamanho adequado ao tamanho dos detectores utilizados. Para a realização de medidas de quimiluminescência, foram utilizados dois fotodiodos (Centronic OSD50-E) e alternativamente foi utilizada uma mini fotomultiplicadora (Hamamatsu -H7468-03). O dispositivo microfluídico proposto suportou vazões de até 3,0 mL/min sem vazamentos e foi avaliado na determinação de peróxido de hidrogênio em soluções padrões, na determinação de hipoclorito em amostras comerciais de água sanitária e na determinação de nitrito em patês comerciais. Os sinais analíticos obtidos para a determinação de peróxido de hidrogênio utilizando detecção com fotodiodos demonstraram uma relação linear (R2=0,99987) para faixa de concentração entre 50 e 200 μmol/L e apresentou frequência analítica 110 injeções/h, enquanto que a determinação utilizando a fotomultiplicadora apresentou uma resposta linear (R2= 0,99999) na faixa de concentrações de 5 a 25 μmol/L e frequência analítica de 150 injeções/h. Para determinação de hipoclorito em amostras comerciais de água sanitária a curva analítica construída a partir dos dados obtidos com o microssistema com detecção por fotodiodos apresentou uma boa resposta linear (R2= 0,99848) na faixa de concentrações de 2 a 20 mg/L e frequência analítica de 80 injeções/h. Para a determinação de nitrito em patês comerciais foi utilizado um microssistema com detecção por fotomultiplicadora, em que os dados obtidos apresentaram uma resposta linear (R2= 0,99965) na faixa de concentração de 10 a 80 μg/L e frequência analítica de 60 injeções/h. Os resultados obtidos nas determinações de hipoclorito e nitrito foram comparados com os respectivos métodos de referência e não apresentaram diferenças significativas ao nível de 95% de confiança. Estes resultados demonstraram a viabilidade de se desenvolver microssistemas de análise por injeção em fluxo com célula de detecção por quimiluminescência integrada. _______________________________________________________________________________________ ABSTRACT / This work describes the development and evaluation of micro flow injection analysis systems based on Urethane – Acrylate photoresist with integrated chemiluminescence detection cell. The deep ultraviolet photolithography was employed to engrave the channels (width of 500 μm and depth of 440 μm, approximately) on plates of Urethane acrylate photoresist - ( UA ), and the detection cell (with serpentine or snail shapes) was developed with 1.0 cm diameter, an appropriate size for adaptation of the used detectors. To perform chemiluminescence measurements, two photodiodes (Centronic OSD50 -E) or, alternatively, a mini photomultiplier (Hamamatsu-H7468-03) were employed. The proposed microfluidic devices can operate with flow rates up to 3.0 ml/min, without leaks, and was evaluated in determining hydrogen peroxide in standard solutions, hypochlorite ions in commercial bleach samples and for the determination of nitrite in commercial pates. The signals obtained for the analytical determination of hydrogen peroxide using photodiodes as transducers demonstrated a linear relationship (R2= 0.99987) in the concentration range between 50 and 200 μmol/L and the analytical throughput of 110 injections/h. The results for the same determination using the photomultiplier showed a linear response (R2=0.99999 ) in the concentration range from 5 to 25 μmol/L and the injection rate of about 150/h. For determination of hypochlorite in commercial bleach samples to the analytical curves obtained with the detection by photodiodes showed a good linear response (R2=0.99848) in the concentration range of 2 - 20 mg/L with analytical frequency of 80 injections/h. The results were compared with the reference method and showed relative deviations of less than 5%. For the determination of nitrite in pates, using a photomultiplier to detect quenching of chemiluminescence, where the data obtained showed a linear response (R2 =0.99965) in the concentration range of 10-80 μg/L and analytical frequency of 60 injections/h. The results were compared with the reference method and no signicant difference was observed in 95% confidence level. These results demonstrated the feasibility of developing microsystems in UA with integrated chemiluminescence detection cells.

Forensic investigation television shows such as police procedurals, rooted in both fact and fiction, have become an ever-popular staple of modern television in the last 20 years. The popularity of these shows has been blamed for generating higher expectations for forensic evidence by juries across America and may also have had the effect of inspiring criminals attempt to cover up their crimes by destroying potential evidence, particularly bloodstains. Luminol is a popular blood detection technique because it can be sprayed throughout an area in a dark room and will chemiluminesce when it interacts with hemoglobin. This chemiluminescence is a signal to investigators that latent blood may be located in that spot. Luminol’s specificity and sensitivity have long been studied. Luminol is a stable molecule that becomes oxidized when it comes in contact with an oxidant such as hydrogen peroxide and a catalyst. In this excited state, the molecule is unstable and forms 3-aminophthalate. This molecule produces light, and the luminescence slowly dies out as the molecule returns to its ground state. Chemicals that disrupt the luminol reaction can be considered interferents. These include cleaning agents, biological agents, foods, and drinks, among others. Compounds such as sodium hypochlorite, sodium percarbonate, and hydrogen peroxide are commonly used as primary cleaning products or as components in popular brands of household cleaners. Such multisurface cleaners, extra strength detergents or other chemicals are readily accessible to someone attempting to clean up a crime scene. Sodium hypochlorite, also known as bleach, has previously been found to cross react with luminol, generating a chemiluminescent reaction whether heme is present or not. Sodium percarbonate is also known as active oxygen and is used in detergents to improve their stain removing capabilities. It can affect the luminol and Bluestar® Forensic tests by causing a negative result, even in the presence of blood. Hydrogen peroxide is a common disinfectant and a necessary component of most presumptive blood tests, however, bulk quantities of it in the luminol reaction stop the reaction from proceeding. Antioxidants, found in many foods and drinks, can inhibit luminescence by preventing heme from being degraded, an important step in order for the luminol reaction to proceed. The purpose of this investigation is to evaluate the effectiveness of common cleaning agents for removing detectable traces of blood based on published studies. Additionally, an attempt was made to determine if cleaning agents completely remove blood or if they disrupt the luminol reaction when a negative luminol result is obtained. To supplement the literature, a limited experiment was carried out and preliminary data was obtained. This investigation finds that some cleaners interfere with the luminol reaction by altering one or more components in a way that prevents the reaction from fully proceeding, even when blood is still present.

Body fluid identification is important in the field of forensic science as it can provide valuable information to an investigation. An accurate method for detecting blood at a crime scene or on evidence is beneficial to an analyst or investigator. A piece of evidence may be any house-hold object or material; therefore, a test must be able to accurately detect blood on a variety of substrates. The most common preliminary testing method for blood is based on the peroxidase-like activity of hemoglobin. Tests such as phenolphthalein (Kastle-Meyer), Ortho-Tolidine (O-Tol), and Luminol utilize this method. The sensitivity of presumptive blood tests was evaluated using a series of diluted bloodstains on six fabrics: fleece, felt, linen, denim, flannel, and terrycloth. In addition to a direct testing method, two indirect methods were tested utilizing a piece of dry filter paper or a moistened cotton swab. The last portion of this study compared commercial field kits to the laboratory-prepared reagents. This study yielded overall sensitivities for Kastle-Meyer, O-Tol, and Luminol of 1:1000, 1:5000, and 1:10000, respectively. The direct testing resulted in a slightly lower sensitivity with fleece versus the other fabrics. Fleece also resulted in slower and weaker reactions compared to thinner fabrics such as denim, linen, and terrycloth. This suggests that highly absorbent fabrics, such as fleece, can have a negative effect on the sensitivity of catalytic color tests such as Kastle-Meyer and O-Tol. The indirect testing methods utilizing a moistened swab or a dry filter paper were less sensitive compared to direct testing methods. The field kits tested in this study mimic the methods of a moistened swab technique, and the results demonstrated that the field kits were about the same sensitivity or less sensitive compared to the indirect testing methods.