Made available in DSpace on 2016-08-19T12:56:36Z (GMT). No. of bitstreams: 1 MIRELA GHISI.pdf: 1324849 bytes, checksum: 5d9ca5c5a49c366f3bf4959e2e942a14 (MD5) Previous issue date: 2011-05-16 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The metals content in biodiesel is directly related with the raw material used and also with the utilized biodiesel production method. In this work, an evaluation of the main metals present in biodiesel samples from different sources was done. The qualitative analysis of the metal content was assessed using the Inductively Coupled Plasma Mass Spectrometry technique after sample digestion in microwave oven. The main metals identified in the analyzed biodiesel samples were Al, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr and Zn. Metals like Ag, As, Ba, Cd, Co, Tl and V have not significant presence in the samples. Among these, Cu and Fe were selected due to their relevance and importance in oxidative process of biodiesel, to the development of an analytical methodology to be used in the determination by Electrothermal Atomic Absorption Spectrometry, and also evaluate the effect of these metals over the oxidative stability of the soy biodiesel. The samples were prepared with tetramethylammonium hydroxide (TMAH), and the pyrolysis and atomization temperatures were optimized pyrolysis and atomization curves. The high pyrolysis temperature adopted, 1000 oC, certainly minimized potential interferences, but calibration had to be carried out with aqueous standard solutions in the presence of the TMAH. The detection limits in the sample (3s, n=10), were quite low 15 ng g-1 and 24 ng g-1 for Cu and Fe, respectively. Seven biodiesel samples, produced from different raw materials, including vegetable seed, waste frying oil and animal fat were analyzed. Accuracy was validated by applying the recovery test (recoveries from 105% to 120%) and through comparison with the obtained results by High Resolution Continuum Source Electrothermal Atomic Absorption Spectrometry. The precision, expressed by the relative standard deviation, was better than 3% for Cu and than 7% for Fe. Copper could be quantified in two and Fe in three of the seven samples. The biodiesel sample from fodder turnip was especially rich in the analytes in comparison to the other samples. The influence of metals Cu and Fe on soy biodiesel oxidative stability was evaluated by Rancimat method through induction period, according with the Standard EN 14112. The metals Cu2+ and Fe3+ were added to the biodiesel samples in the form of theirs salts, and different storage times of the samples were evaluated. Due to the catalytic behaviour of these metals, the oxidative stability of the samples was affected, even under low metal concentrations. Compared to Cu2+, the effect over the biodiesel stability was higher when Fe3+ was added. / A presença de metais no biodiesel está diretamente relacionada com a matéria-prima utilizada e também com o processo utilizado para a obtenção do biodiesel. Neste trabalho realizou-se uma avaliação dos principais metais presentes em amostras de biodiesel provenientes de diferentes fontes. A análise semi-quantitativa nas amostras de biodiesel foi realizada utilizando a técnica de Espectrometria de Massa com Plasma Indutivamente Acoplado após a digestão das amostras em micro-ondas. Os principais metais identificados nas amostras de biodiesel analisadas são Al, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr e Zn. Metais como Ag, As, Ba, Cd, Co, Tl e V não estão presentes em concentrações significativas nessas amostras. Em função de sua relevância e importância em processos oxidativos do biodiesel, selecionou-se Cu e Fe para o desenvolvimento de uma metodologia analítica para a determinação destes por Espectrometria de Absorção Atômica com Atomização Eletrotérmica e também a avaliação do efeito destes metais sobre a estabilidade oxidativa do biodiesel de soja. As amostras foram preparadas com hidróxido de tetrametilamônio (TMAH), e as temperaturas de pirólise e atomização foram otimizadas através de curvas de pirólise e atomização. A alta temperatura de pirólise adotada, 1000 oC, certamente ajudou a minimizar possíveis interferências; porém, a calibração teve de ser realizada com padrões aquosos na presença de TMAH. Os limites de detecção (3s, n = 10), na amostra, foram baixos, 15 ng g-1 e 24 ng g-1 para Cu e Fe, respectivamente. Sete amostras de biodiesel, produzidas de diferentes matérias-primas, incluindo óleos vegetais, óleo de fritura e gordura animal foram analisadas. A exatidão foi avaliada através do teste de recuperação (recuperações de 105% a 120%) e através da comparação com os resultados obtidos por Espectrometria de Absorção Atômica de Alta Resolução com Fonte Contínua e Atomização Eletrotérmica. A precisão, expressa pelo desvio padrão relativo foi melhor que 3% para Cu e que 7% para Fe. Cobre pôde ser quantificado em duas e Fe em três das sete amostras. A amostra de biodiesel proveniente do nabo forrageiro era especialmente rica nos analitos comparada às outras amostras. A influência dos metais Cu e Fe sobre a estabilidade oxidativa do biodiesel de soja foi avaliada pelo método Rancimat através do período de indução, de acordo com a Norma EN 14112. Os metais Cu2+ e Fe3+ foram adicionados nas amostras de biodiesel na forma de seus sais, e foram avaliados diferentes tempos de armazenamento das amostras. Devido ao efeito catalítico destes metais, a estabilidade oxidativa das amostras analisadas foi reduzida mesmo na presença de baixas concentrações dos metais. O efeito do Fe3+ sobre a estabilidade do biodiesel foi significativamente maior quando comparado ao Cu2+.

La tesi è divisa in quattro manoscritti. Lo scopo è lo studio di tre aspetti, come casi-studio indipendenti, all’interno della gestione della catena alimentare dai mangimi al latte. Il primo manoscritto riguarda la fortificazione del latte bovino con iodio e selenio allo scopo di migliorare la qualità del latte e dei suoi derivati; il secondo riguarda la contaminzione dei mangimi con melamina come fattore di rischio per l’industria lattiero-casearia e la salute pubblica. Gli ultimi due lavori sono corollari alla qualità del latte derivante dallo iodio: ovvero un confronto analitico tra procedure di determinazione dello iodio in latte crudo, e uno studio di speciazione dello iodio inorganico nel latte crudo fortificato. Il primo lavoro offre informazioni per meglio comprendere i fattori coinvolti nel miglioramento della concentrazione dello iodio e del selenio nel latte a seguito di una fortificazione della dieta animale. Riguardo la melamina, lo studio conferma il passaggio di essa dai mangimi al latte e la sua rapida escrezione anche a livelli bassi di ingestione da parte dell’animale; uno scarso passaggio dal latte al formaggio. Il terzo lavoro mostra che, per analisi dello iodio con ICP-MS, l’estrazione dell’elemento con soluzione d’ammoniaca è una valida alternativa al metodo ufficiale con TMAH. La speciazione dello iodio inorganico nel latte scremato è un’operazione possibile utilizzando delle diluizioni con soluzione d’ammoniaca (quarto manoscritto). / The thesis is divided into 4 manuscripts. The aim is to study three aspects, as independent case studies, within the quality management of feed-for-food system. The first manuscript is about the fortification of feeds with iodine and selenium to improve the quality of cow’s milk and derivatives; the second one investigates the contamination of feeds with melamine as risk factor for dairy industries and human health. The last two works are corollaries to the iodine-linked quality of milk: i.e. a comparison between analytical procedures for the determination of iodine in raw milk, and a speciation study of iodine in fortified milk. The first work helps to better understand factors involved in improvement of milk iodine and selenium concentration and CO following supplementation with inorganic sources. Regarding melamine, the study confirmed the pathway for its transmission from feed to milk and its rapid excretion, also at a very low level of melamine ingestion by cows; and a low transfer from milk to cheese. The third study shows that the ammonia extraction of iodine is a valid alternative to the official method with TMAH for iodine determination in milk, by using ICP-MS. The speciation of inorganic iodine in skimmed milk is feasible by using ammonia dilution (fourth manuscript).

Le traitement de boues de station d'épuration (Boues activées de Marrakech) en mélange avec déchets verts (Palmier dattier) selon deux mélanges dont les proportions : A (1/3 Boues + 2/3 Déchets de palmier) et B (1/2 Boues + 1/2 Déchets de palmier), a été effectué par la filière du compostage, pendant six mois. Au cours du co-compostage, l’intense activité microbienne s’est traduite par une augmentation de température (autour 65 C°) au cours des premières semaines (phase thermophile) et un taux de décomposition final de l’ordre de 40%. Après six mois de co-compostage, le compost final est caractérisé par un rapport C/N voisin de 10, un rapport de NH4+/NO3- < 1, un pH autour de la neutralité signe de maturité des composts. L’analyse FTIR a montré une diminution de l'absorbance des bandes aliphatiques et l'augmentation de la structure de bandes d'absorbance aromatiques reflètent l'état d'avancement du processus d'humification. Le taux d’abattement des lipides totaux est de l’ordre de 43%. Les esters méthyliques d’acide gras (FAMEs) des Gram-positif (i,C15 :0) ont augmenté durant la phase thermophile. Les FAMEs d’origine non spécifique (C6 :0, C14 :0) ont connu une intense diminution, les FAMEs de bactéries non spécifiques représentent une grande teneur durant la phase thermophile. L’indice CPI a augmenté à la fin du co-compostage indiquant l’enrichissement du compost en FAMEs d’origine végétale. Les principaux composés ligneux identifiés, au cours du co-compostage, par Py-GC-MS, sont classés en deux groupes. Le premier est constitué de 7 composés dont la teneur diminue au cours du co-compostage, parmi lesquels : Toluène, 2,4-diméthylbenzène, éthylbenzène, Styrène, 1-éthyl-2-méthylbenzène, 4-méthylphénol et 2-méthylnaphthalène. Le deuxième groupe est constitué de 4 composés qui augmentent au cours du co-compostage : phénol, benzofuran, éthylméthoxyphénol et diméthoxyphénol. Les principaux stéroïdes identifiés sont les C27-C29 sterènes, stanols, 5β-cholesta-3-one, cholesta-3,5-diène et 2 thiostéranes. A l’exception des thiosteranes et quelques composés de C27-C29 cholestenes la concentration relative des stéroides diminue au cours du processus suit à leur attaque microbien. L’abattement total de la teneur des stéroïdes est corrélé positivement avec les indicateurs de maturité du compost (C/N et NH4+/NO3-) ce qui ouvre la voie à une éventuelle utilisation des stéroïdes comme indicateur de dépollution et de maturité de compost. 12 isolats d’actinomycètes ayant une activité antimicrobienne vis-à-vis d’un large spectre des germes pathogènes ont été isolés sur le milieu sélectif CTEA. Le degré d’hygiénisation est confirmé par la diminution de la concentration des coliformes fécaux et totaux, et l’abattement des œufs d’helminthes identifiés (Ascaris sp., Capillaria sp., et Trichuris sp.) vers la fin du co-compostage. La phytotoxicité, déterminée par l’effet des extraits hydrosolubles à différents stades de co-compostage sur la germination et la croissance des radicules (Navet, Cresson, Laitue, Luzerne), a diminué et l’indice de germination dépasse 100%, après six mois de co-compostage. La génotoxicité du chrome hexavalent (Cr(VI)) du substrat de co-compostage est corrélée positivement avec la fréquence des micronoyaux (MN). Après six mois de co-compostage le taux des MN diminue avec un taux d’abattement de 70,4% et 77,2% avec l’abattement de la concentration du Cr(VI) avec 58 et 58,6% respectivement pour le mélange A et B. Ceci ouvrira la voie d’utilisation de cet indice comme un indice de maturité des composts. La diminution de la phytotoxicité et la génotoxicté au cours du co-compostage confirme l’état de stabilisation et de la maturité des co-composts, ce qui pemettra l’épandage de ces composts en tant qu’amendement organique des sols sans risque de contamination du système sol-plante. / The co-composting of activated sludge and lignocellulose waste (palm tree waste) was monitored to study the behaviour of two mixtures, referred to as A (1/3 sludge + 2/3 palm waste) and B (1/2 sludge + 1/2 waste palm) for 6 months. The biotransformation was evaluated by physicochemical and spectroscopic analyses. The thermophilic phase is characterized by a rise in temperature, which peaked at 65°C. This is the result of intense microbial activities. The final composts exhibited a higher degree of decomposition than the controls as shown by a decomposition rate of about 40%, decrease of C/N ratio to around 10 and NH4 +/NO3 - ratio below 1. The decrease of aliphatic absorbance bands and the increase of aromatic absorbance bands follow the progress of the humification process. Total extractable lipid was decreased by 43%. The fatty acid methyl esters (FAMEs) from Gram-positive bacteria (i, C15: 0) increased during the thermophilic phase. FAMEs from non-spécific origin (C6 :0, C14 :0) exhibited a decrease toward the end of co-compostin, linear FAMEs from non-specific bacteria underwent a decrease during co-composting. The CPI index thus increased at the end of the composting process, indicating that the final product was proportionally richer in fatty acids of plant origin. Two lignin groups were distinguished by Py-GC-MS. Group 1 contained toluene, 2,4-dimethylbenzene, ethylbenzene, styrene, 1-ethyl-2-methylbenzene, 4-methylphenol and 2-methylnaphthalene; their relative proportions decreased during co-composting. A second group of 4 components showed concentrations that increased with co-composting time: phenol, benzofuran, ethylmethoxyphenol and dimethoxyphenol. The main steroids identified were C27-C29 sterenes and stanols, 5β-cholesta-3-one, cholesta-3,5-diene and 2 thiosteranes. Except for thiosteranes and some of the C27-C29 cholestenes, the relative concentrations decreased during co-composting due to microbial degradation. The changes in steroids during co-composting, was positively correlated with the physico-chemical parameters of mature compost, especially C/N and NH4 +/NO3 - ratios, opening the way for the use of steroids as indicators of pollution and compost maturity. On the selective CTEA medium, 12 active strains of isolated actinobacteria presented a suppressive action against various pathogens. This may justify that a biotic factor is also an important factor contributing to making co-composting substrates hygienic. The degree hygiene reached is confirmed by the reduction in the faecal and total coliforms, and by the abatement of identified helminth eggs (Ascaris sp., Capillaria sp., and Trichuris sp.) towards the end of the process. The phytotoxicity determined by the effect of aqueous extract, at various stages of the co-composting, performed by monitoring the number of germinated seeds and the rootlets growth of turnip, watercress, alfalfa, and lettuce was decreased, and the growth of radicals that have a germination index that exceeds 100% after six months of co-composting. Hexavalent chromium (Cr(VI)) genotoxicity showed a positive correlation with micronucleus (MN) frequency. After six months of co-composting, the MN rate decreased significantly by 70.4 and 77.2% with decreasing Cr(VI) concentration with 58 and 58.6%, for mixtures A and B respectively. That indicates their suitability for use as a maturity index. During co-composting the abatement rate of phytotoxicity and genotoxicity confirme the maturation and stabilization degree of co-composting end products which encourages their recycling in agriculture as a fertilizer for the soil without any contamination of the soil-plant system.

La caractérisation de nanomatériaux dans des matrices alimentaires et animales suscite un intérêt scientifique important afin d’évaluer les risques potentiels de l’exposition liés à l’utilisation grandissante des nanomatériaux par plusieurs industries, y compris un certain nombre d’applications agroalimentaires. Un facteur limitant à l’étude et la réglementation des nanomatériaux dans des matrices complexes telle que la nourriture est l’absence de méthodes standardisées pour l’extraction et l’analyse de nanoparticules, tout en évitant l’altération de certaines caractéristiques physicochimiques des nanoparticules. Les travaux présentés dans ce mémoire abordent l’optimisation de plusieurs approches de préparation d’échantillon (hydrolyse enzymatique et alcaline) pour l’extraction de nanoparticules d’Ag préalablement équilibrées dans une matrice de boeuf haché mi-maigre. Les nanoparticules extraites ont été analysées par spectrométrie de masse à plasma à couplage inductif en mode particule unique (SP-ICP-MS) permettant la mesure de leur taille et concentration, mais aussi de la concentration en métal dissous, le tout à de très faibles concentrations (de l’ordre du ng/L). La validation de l’analyse par SP-ICP-MS a été réalisée par évaluation de la répétabilité, de la détermination des limites de détection et par une investigation de l’influence du traitement de données sur l’interprétation des résultats. Les pertes de nanoparticules lors de la préparation des échantillons ont été minimisées par l’identification et l’optimisation de paramètres clés tels que la composition du médium d’extraction, l’utilisation d’ultrasons et de la manipulation de l’échantillon après dégradation de la matrice. Les meilleurs recouvrements ont été obtenus par hydrolyse alcaline de la matrice en utilisant de l’hydroxyde de tetramethylammonium (TMAH), mais les échantillons obtenus étaient moins stables et plus susceptibles aux altérations des propriétés physicochimiques des nanoparticules que pour la dégradation par hydrolyse enzymatique utilisant lipase et pancréatine de porc. / The regulation and characterization of nanomaterials in foods and animal matrices are of great interest due to the potential risks associated with their exposure and the increasing number of instances where they are used within the food industry. One factor limiting the scientifically rigorous regulation of nanoparticles in foods is the lack of standardized procedures for the extraction of nanoparticles (NP) from complex matrices, without alteration of their physico-chemical properties. To this end, two sample preparation approaches (enzymatic- and alkaline-based hydrolyses) were tested and optimized in order to extract 40 nm Ag NP, following their equilibration with a fatty ground beef matrix. Extracted NP were characterized using single particle inductively coupled plasma mass spectrometry (SP-ICP-MS), allowing the determination of NP size and concentrations and also dissolved metal concentrations at trace levels. Validation of the SP-ICP-MS analysis was achieved by an evaluation of the repeatability and accuracy and by a determination of the various detection limits. Finally, we also looked into the influence of data treatment on interpretation of the results. NP losses during the sample preparation were minimized by identifying and optimizing key parameters such as the composition of the extraction media, usage of ultrasonication or the handling of the sample after separation from the undigested matter, among other points. The alkaline approach using TMAH (tetramethylammonium hydroxide) was found to have the highest recoveries, however processed samples were found to be less stable and more prone to alteration of the Ag NP physicochemical characteristics than samples processed using an enzymatic digestion based upon pork pancreatin and lipase.