Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16387号 / 工博第3468号 / 新制||工||1524(附属図書館) / 29018 / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 田中 宏明, 教授 清水 芳久, 教授 伊藤 禎彦 / 学位規則第4条第1項該当

Guang Fu Chen. / "May 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 194-221). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

The rejections of selected N-nitrosamines by commonly used high-pressure nanofiltration (NF) and reverse osmosis (RO) membranes were quantitatively evaluated using a bench-scale cross-flow filtration apparatus. The selected nitrosamines included N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), N-nitrosopyrrolidine (NPYR), N-nitrosodiethylamine (NDEA), N-nitrosodi-n-propylamine (NDPA), N-nitrosodi-n-butylamine (NDBA) and N-nitrosodiphenylamine (NDPHA). Nitrosamine rejections were evaluated under steady state at elevated feed concentrations, since NDMA rejections were found to be consistent with feed concentrations over three orders of magnitude. The steady-state nitrosamine rejections by NF membranes varied significantly, from 9 to 75%, depending on nitrosamine compounds and tested membranes. For hydrophilic compounds, rejections increased with increasing molecular weight. The nitrosamine rejections by brackish RO membranes reached as high as 97% for higher molecular weight nitrosamines. However, for low molecular weight nitrosamines such as NDMA, rejections as low as 54% were observed. This low level of rejections was attributed to diffusive solute transport being more effective than convective transport. Physicochemical properties such as molecular weight and aqueous diffusivity showed reasonable correlations with nitrosamine permeability constants.

Significant variability in cured leaf tobacco-specific nitrosamine (TSNA) content is commonly observed when sampling within dark air-curing barns. This variability may be due to inconsistency in the curing environment within different areas of the barn. A study was initiated in 2012 through support from a CORESTA Study Grant to evaluate if leaf TSNA content is related to microenvironmental conditions in the barn. Seed screened for low conversion of nicotine to nornicotine (sc) and high converter (HC) selections of TR Madole dark tobacco were cured in barns near Princeton and Lexington, Kentucky in 2012 and 2013. Temperature and relative humidity were measured with data loggers placed at 27 locations within each barn for the duration of curing. TSNA content was determined from 20-leaf samples collected from each selection at each of the 27 locations within each barn. There were no significant effects of individual data logger placement in either variety selection on hours above 24°C temperature, hours above 80% relative humidity, or TSNA; therefore, we investigated these data within 3-dimensional aspects of tier, room, and bent within each barn. There were various effects of tier, room, and bent on temperature, relative humidity, and TSNA; but limited significant relationships between temperature, relative humidity, and TSNA.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2005. / Härtill 4 uppsatser.

Orientador: Susanne Rath / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-18T12:46:57Z (GMT). No. of bitstreams: 1 Canaes_LarissadeSouza_D.pdf: 2777887 bytes, checksum: 4eff3d6893f034649d50087cfb9d903b (MD5) Previous issue date: 2011 / Resumo: As N-nitrosaminas (NA) são compostos N-nitrosos, que mostraram ser carcinogênicas para uma grande variedade de animais experimentais. Além disso, elas apresentam atividade teratogênica e mutagênica. As NA foram encontradas, durante as últimas três décadas, em uma variedade de produtos de consumo, incluindo cosméticos e produtos de higiene e suas matérias-primas. As NA mais comumente encontradas em cosméticos são a N-nitrosodietanolamina (NDELA), N-nitrosomorfolina (NMOR) e N-nitrosodimetilamina (NDMA), em concentrações que variam desde mg kg até mg kg. Os objetivos deste trabalho foram a avaliação do comportamento eletroquímico de NA sobre eletrodo de diamante dopado com boro e construção de uma célula amperométrica para ser associada ao cromatógrafo líquido de alta eficiência (HPLC), assim como o desenvolvimento e validação de métodos para a determinação de NA em xampu, usando a cromatografia líquida, associada ao detector eletroquímico desenvolvido, arranjo por fotodiodos e espectrometria de massas. O comportamento eletroquímico das NA foi estudado usando voltametria cíclica e voltametria de onda quadrada; foram avaliados composição, concentração e pH do eletrólito suporte. A separação da NA foi realizada em uma coluna C18 XBridge¿ e uma fase móvel composta de água/acetonitrila e eluição por gradiente. No preparo de amostras foram avaliadas a extração líquido-líquido, extração em fase sólida (C18 e sílica) e a dispersão da matriz em fase sólida. A performance dos diferentes sistemas de detecção associadas ao HPLC foram comparados na determinação de NA em xampu. Finalmente, o método de cromatografia líquida-espectrometria de massas foi validado para a determinação de NMOR e NDMA em xampu, mediante avaliação dos seguintes parâmetros: faixa linear, linearidade, precisão intra-dia e inter-dia, seletividade, limite de detecção, limite de quantificação e exatidão. O método foi aplicado na determinação de NA em amostras de xampu / Abstract: N-nitrosamines (NA) are N-nitroso compounds, showed to be carcinogenic in a wide variety of experimental animals. In addition, they also present mutagenic and teratogenic activities. N-nitrosamines have been found during the last three decades in a variety of consumer products, including cosmetic and personal care products, and their raw materials. The most common NA detected in cosmetics were N-nitrosodiethanolamine (NDELA), N-nitrosomorpholine (NMOR) and Nnitrosodimethylamine (NDMA), in concentrations varying from mg kg to mg kg. The aims of this work were the evaluation of the electrochemical behavior of NA on a boron doped diamond electrode and construction of an amperometric cell to be coupled to high performance liquid chromatography (HPLC), as well as the development and validation of methods for determination of NA in shampoo, using liquid chromatography coupled to the developed electrochemical cell, photodiode array and mass spectrometry detectors. The electrochemical behavior of NA was studied using cyclic voltammetry and square wave voltammetry; composition, concentration and pH of the electrolyte were evaluated. The separation of NA was achieved using a C18 XBridge¿ column and mobile phase of water and acetonitri le under gradient elution. For sample preparation liquid-liquid extraction, solid phase extraction (C18 and silica) and matrix solid phase dispersion were evaluated. The performance of the different detectors coupled to liquid chromatography to the NA determination in shampoo was compared. Finally, a liquid-chromatography-mass spectrometry method was validated to the determination of NMOR and NDMA in shampoo, thorough the following parameters: linear range, linearity, intra-day and inter-day precision, selectivity, limit of detection, limit of quantification and accuracy. The method was applied to the determination of NA in shampoo samples / Doutorado / Quimica Analitica / Doutor em Ciências

Orientador: Felix Guillermo Reyes Reyes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-05T16:12:22Z (GMT). No. of bitstreams: 1 Dutra_CamilaBraga_M.pdf: 978776 bytes, checksum: 0edde3491d6aa306de0b78cbd74ea7fa (MD5) Previous issue date: 2006 / Resumo: Nitrito e nitrato são os principais ingredientes usados no processo de cura conferindo aroma e cor avermelhada caracteristicos dos produtos curados como, por exemplo, a salsicha e atuando como antioxidantes e antimicrobianos, impedindo o crescimento de Clostridium botulinum. O efeito tóxico mais relevante da presença de nitrato e nitrito é a formação de nitrosaminas as quais são compostos N-nitroso que podem ser formados da reação de agentes nitrosantes com aminas secundárias ou terciaérias. a maior exposição a estes compostos acontece através dos alimentos, onde o modo de preparo e processamento tem grande influência na quantidade de nitrosaminas presente no alimento, sendo que a formação de nitrosaminas durante o processamento pode ser reduzida por incorporação de inibidores, tais como, ácido ascórbico ou xtocoferol. A nitrosaminas voláteis são as que mais ocorrem em alimentos, e são potentes carcinógenos em animais de laboratório induzindo tumores em vários orgãos. O propósito do presente estudo foi otimizar e validar o método de amostragem "headspace" por microestração em fase sólida (SPME, do inglês Solid Phase Microextraction) usando cromatografia gasosa acoplada a um dectector de quimioluminescência ) TEA, do inglês Thermal Energy Analyser) para a determinação de nitrosaminas voláteis em salsichas "hot-dog". As amostras foram adquiridas bo comércio da cidade de Campinas, São Paulo. Nas amostras analisadas não foram encontradas nitrosaminas voláteis em níveis detectáveis. Diferentes modos de preparo, como cozimento em água e fritura, não contribuíram para a formação de nitosaminas. Os resultados indicam a ausência de nitrosaminas nas amostras analisadas devido, possivelmente, aos baixos teores de nitrito disponível para a reação com as aminas prsentes na carne e/ou pela ação efetiva do ascorbato de sódio atuando como inibidor da formação de nitrosaminas / Abstract: During the curing process, nitrite and nitrate are the principal ingridients udes for curing. They confer and colored color characteristic of the cured meat as sausage, and act as antioxidants and antimicrobial, comtrolling the growth of Clostridium botulinum. The most important toxic effect of the presence of nitrate and nitrite is the formation of nitrosamines. These are N-nitroso compounds that can be formed by the reaction of the nitrosating agents with secundary or tertiary amines. The major exposure to these compounds happens through foodstuffs, where the procedures of preparation and processing have great influence in the present amount of nitrosamines in the food. The formation of nitrosamines during the processing can be reduced by incorporation of inhibitors, such as, ascorbic acid or x-tocoferol. The volatile nitrosamines are the ones that occur in foods more frequentely, and are strong carcinogens in laboratory animals inducing tumors in a variety of organs. The purpose of the present study was to optimize and to validate a simple method using headspace sampling by solid-phase microextraction gas chromatography with thermal energy analyzer detector (HS-SOME-GC-TEA) for the determination of volatile nitrosamines in hot-dog sausages. The samples were purchased from local markets (Campinas, São Paulo). In the analyzed samples volatile nitrosamines have not been found in detectable levels. Different cooking procedures, as boiled in water and frying, did not contributr to the formation of nitrosamines. The results indicate the absence of nitrosamines in the samples nalyzed possibly because of low content of available nitrite for the reaction with the amines found in the meat and because of the action of dodium ascorbate acting as inhibitor for the formation of nitrosamines / Mestrado / Mestre em Ciência de Alimentos

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21308号 / 工博第4506号 / 新制||工||1701(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 田中 宏明, 教授 清水 芳久, 教授 伊藤 禎彦 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The induced circular dichroism (ICD) of several chiral nitrosamines and various chiral reagents has been investigated. The interaction is attributed to a 1:1 hydrogen bonded complex between the NO group of the nitrosamine and the hydroxyl groups of alcohols and polyols, or the amino group of amines. Only those chiral reagents possessing large differences in size of the groups about the hydrogen bonding site contributed to CD anomalies. The acyclic 2-octanols did not give observable Cotton effects, presumably due to the similarity in size of the methyl and methylene groups and rotational freedom of the acyclic system. The signs of the Cotton effects could be correlated with the absolute configuration of the sterically hindered alcohols and amines. Only the alpha, axial hydrogens of conformationally biased, heterocyclic nitrosamines were found to undergo selective hydrogen-deuterium exchange, suggesting that this feature is critical for nitrosamine carcinogenicity.

Tableau d’honneur de la Faculté des études supérieures et postdoctorales, 2010-2011 / Ce projet de recherche a été entrepris afin de caractériser la présence spatio-temporelle de plusieurs jV-nitrosamines dans l'eau de sept réseaux de distribution d'eau potable québécois considérés comme vulnérables à la présence de ces sous-produits de la désinfection (SPD) émergents. Il s'agit de la première étude sur la présence de N-nitrosamines dans des réseaux d'eau potable au Québec. Six campagnes d'échantillonnage ont été menées à plusieurs points de prélèvement dans chacun des réseaux pendant une année. Les résultats démontrent que les N-nitrosamines, principalement la N-nitrosodiméthylamine (NDMA), sont peu présentes dans l'eau potable des réseaux étudiés. Les concentrations détectées sont largement inférieures à celles observées dans les études nord-américaines récentes. Aucun des 195 échantillons prélevés n'a excédé la norme ontarienne de 9 ng/L pour la NDMA (valeur maximale observée de 3,3 ng/L). La N-nitrosométhyléthylamine (NMEA) et la N-nitrosopipéridine (NPip) ont été détectées une seule fois, avec des concentrations de 3,7 ng/L et 6 ng/L, respectivement. À notre connaissance, la NMEA n'avait jamais été détectée dans des réseaux d'eau potable jusqu'à maintenant. La chloramination a été identifiée comme le principal facteur de vulnérabilité à la présence de N-nitrosamines, mais la qualité de l'eau et certains paramètres opérationnels semblent également liés à leur présence. Les concentrations de NDMA en fin de réseau sont généralement supérieures à celles observées à la sortie de l'usine. Aucune saison n'a semblé plus propice à la formation de N-nitrosamines. Finalement, une certaine corrélation entre la présence de N-nitrosamines et les niveaux de trihalométhanes (THM) et d'acides haloacétiques (AHA) a été observée dans des réseaux spécifiques.