Ziel der vorliegenden Arbeit war es, Screening–Methoden zu prüfen, um auf einfache, kostensparende Weise und mit ausreichender statistischer Sicherheit festzustellen, ob der Erreger der Paratuberkulose (Mycobacterium avium ssp. paratuberculosis) in einer Herde vorhanden ist oder nicht. Dazu wurden zwei auf dem kulturellen Erregernachweis beruhende Verfahren, die Untersuchung individueller Kotproben auf der Basis von Stichproben und die Untersuchung von Umgebungskotproben, einem serologischen Untersuchungsansatz, dem Nachweis von MAP–Antikörpern nach Aufkonzentrierung in gepoolten Einzelmilchproben, gegenübergestellt. Als Referenzmethode diente die kulturelle Einzeltieruntersuchung aller über 24 Monate alten Tiere des jeweiligen Bestandes. In 20 Thüringer Milchviehherden mit bekannter Einzeltierprävalenz wurden 5063 Einzeltierkotproben, 200 Umgebungskotproben und 262 aufkonzentrierte Milchpools aus 4337 laktierenden Rindern untersucht. Zusätzlich wurde eine systematische retrospektive Stichprobenkalkulation (nStichprobe = 1458 Einzeltierkotproben) vorgenommen. Die Kultivierung der Einzeltierkotproben und der Umgebungskotproben erfolgte über 12 Wochen auf HEYM–Nährmedium mit anschließender Speziesidentifizierung durch PCR und Ziehl–Neelsen–Färbung. Die Umgebungskotproben wurden zu zwei Untersuchungszeitpunkten (Frühjahr und Sommer) an jeweils fünf Lokalisationen eines Betriebes entnommen: Abkalbebereich, Melkbereich einschließlich Vorwartehof, Laufbereich, Haupttriebweg, Übergang zum Kälberbereich. Die Untersuchung der Milchpools erfolgte nach vorheriger Aufkonzentrierung mittels zweier verschiedener ELISAs. Im Frühjahr entnommene Umgebungskotproben aus 16 MAP–positiven Betrieben detektierten das Vorhandensein des Erregers in neun Betrieben (56,3 %). Betriebe mit einer Einzeltierprävalenz von über 4,5 % wurden in neun von zehn Fällen (90 %) sicher erkannt. Im Sommer entnommene Umgebungskotproben fielen durch eine sehr starke Kontamination auf. Von den 16 MAP–positiven Beständen wurden 15 Herden (93,7 %) mittels Stichprobenuntersuchung als Bestand mit Paratuberkulosevorkommen identifiziert, wobei lediglich ein Bestand mit einer Einzeltierprävalenz von 0,49 % nicht detektiert wurde. Die serologische Untersuchung der Milchpools lieferte keine verwendbaren Ergebnisse. Mit Hilfe der Untersuchung von Umgebungskotproben lassen sich Herden mit einer durch kulturelle Untersuchung ermittelten Einzeltierprävalenz von 4,5 % und darüber mit hinreichender Sicherheit auffinden. Bei der Bewertung dieses Schwellenwertes ist zu beachten, dass bei Verwendung von nur einem Kulturröhrchen je Kotprobe von einer Sensitivität der Methode von 60 % im Vergleich zur Verwendung von drei Kulturröhrchen auszugehen ist. Für eine Überwachung unverdächtiger Herden ist die Sensitivität dieses Untersuchungsansatzes jedoch zu gering. Die individuelle kulturelle Untersuchung einer Stichprobe zeigte eine ausreichend hohe Sensitivität, um bei der Überwachung größerer unverdächtiger Herden eingesetzt werden zu können. Ein Einsatz serologischer Milchuntersuchung ist zur Bewertung von Beständen zur Ermittlung des MAP–Infektionsstatus gegenwärtig nicht zu empfehlen. Für die Überwachung größerer, als Paratuberkulose–unverdächtig anerkannter Bestände ist somit ein wechselnder Einsatz von Einzeltierkotproben aller Rinder über 24 Monaten und einer aussagekräftigen systematischer Stichprobenuntersuchung möglich und trägt damit zur Erleichterung der derzeit noch zeit– und kostenintensiven Paratuberkulose–Diagnostik bei.

<p>In South Africa, it is estimated that approximately 70% of the population frequently make use of traditional medicinal plants for their health care needs. The use of Lessertia frutescens by the&nbsp / various cultural groups in South Africa dates back to the earlier civilizations and continues to be used today to treat a multitude of ailments. To get the best results from a medicinal plant, one&nbsp / &nbsp / would need to ensure that the crude material is of good quality through interventions like being properly grown, well dried and correctly processed. This would add a measure of quality&nbsp / assurance, which will contribute towards the safety and efficacy aspect of herbal medicine. The aim of this study was to investigate what impact a particular season of harvest and the time in&nbsp / storage would have on the flavonoid and triterpenoid marker levels of Lessertia frutescens. To achieve this, the following was investigated: (1) storage variation of Lessertia frutescens leaves&nbsp / by comparing the results obtained from the High Performance Liquid Chromatography (HPLC) analysis of the flavonoids and triterpenoids, (2) seasonal variation of Lessertia frutescens&nbsp / leaves by comparing the results obtained from the HPLC analysis of the flavonoids and triterpenoids, (3) leaf and stem variation of Lessertia frutescens by comparing the results obtained from HPLC analysis of the flavonoids and triterpenoids. The hypotheses were: (1) the stored sample would indicate the same level of the biomarkers for the flavonoids and triterpenoids, as that of&nbsp / the freshly prepared sample, (2) the sample that was harvested during the summer season would indicate higher levels of the biomarkers of&nbsp / flavonoids and triterpenoids than the other three&nbsp / seasons, (3) the leaf sample would indicate the same level of the biomarkers for the flavonoids and triterpenoids, as that of the stem sample. An Agilent 1200 series HPLC was used for the&nbsp / determination of the flavonoids sutherlandin A and sutherlandin D as well as the triterpenoids sutherlandioside B and sutherlandioside D. Results show that for both sutherlandin A (summer:&nbsp / 3.67 &plusmn / 2.88 mg/ml / storage: 4.07 &plusmn / 2.88 mg/ml) and D (summer: 4.10 &plusmn / 1.06 mg/ml / storage: 4.25 &plusmn / 1.06 mg/ml) show significantly (P &lt / 0.0001) higher concentrations in the case of the storage&nbsp / amples. For both sutherlandioside B (summer: 3.01 &plusmn / 0.39 mg/ml / storage: 2.82 &plusmn / 0.39 mg/ml) and D (summer: 5.82 &plusmn / 0.42 mg/ml / storage: 4.66 &plusmn / 0.42 mg/ml) show significantly (P &lt / &nbsp / .0001)&nbsp / higher concentrations in the case of the fresh summer samples.For the seasonal comparison, results show that for sutherlandin A (summer: 3.67 &plusmn / 12.49 mg/ml / autumn: 4.75 &plusmn / &nbsp / 12.49 mg/ml / winter: 4.23 &plusmn / 12.49 mg/ml / spring: 6.56 &plusmn / 12.49 mg/ml) show significantly (P &lt / 0.0001) higher concentrations in the case of the spring sample. For sutherlandin D (summer: 4.10&nbsp / &nbsp / 10.32 mg/ml / autumn: 6.37 &plusmn / 10.32 mg/ml / winter: 5.25 &plusmn / 10.32 mg/ml / spring / 6.08 &plusmn / 10.32 mg/ml) show significantly (P &lt / 0.0001) higher concentrations in the case of the autumn sample. For both sutherlandioside B (summer: 3.01 &plusmn / 7.19 mg/ml / autumn: 2.15 &plusmn / 7.19 mg/ml / winter: 2.89 &plusmn / 7.19 mg/ml / spring: 1.47 &plusmn / 7.19 mg/ml) and D (summer: 5.82 &plusmn / 14.48 mg/ml / autumn: 3.33 &plusmn / 14.48 mg/ml / winter: 4.23 &plusmn / 14.48 mg/ml / spring: 2.50 &plusmn / 14.48 mg/ml) show significantly (P &lt / 0.0001) higher concentrations in the case of the autumn sample. For the summer&nbsp / leaf/stem comparison, results show that for sutherlandin A (leaf: 3.67 &plusmn / 8.18 mg/ml / stem: 4.67 &plusmn / 8.18 mg/ml) show significantly (P &lt / 0.0001) higher concentrations in the case of the stem&nbsp / sample. For the sutherlandin D (leaf: 4.10 &plusmn / 4.81 mg/ml / stem: 3.31 &plusmn / 4.81 mg/ml) show significantly (P &lt / 0.0001) higher concentrations in the case of the summer leaf sample. For both the&nbsp / sutherlandioside B (leaf: 3.01 &plusmn / 4.24 mg/ml / stem: 3.62 &plusmn / 4.24 mg/ml) and D (leaf: 5.82 &plusmn / 0.42 mg/ml / stem: 5.80 &plusmn / 0.42 mg/ml) show significantly (P &lt / 0.0001) higher concentrations in the&nbsp / case of the stem samples. Results demonstrate that the production of secondary metabolites are influenced by&nbsp / &nbsp / environmental factors like seasonal harvesting, as indicated by the variation in the chemical constituent composition of Lessertia frutescens depending on the season collected in. Moreover, the storage of Lessertia frutescens for a period of one year resulted in an&nbsp / increase of two of the four constituents being monitored. There was slight variations in the chemical constituents, depending on whether the leaf or stem material of Lessertia frutescens was being used. Finally, the type of chemical constituent being monitored was also important in the consideration of this study. Therefore, this study can be seen as a starting point to further&nbsp / &nbsp / investigations of these aspects, which are of clinical, pharmacological and economic</p>

Platinum-based drugs are an important group of alkylating-like agents which are used in cancer chemotherapy treatment. Cisplatin and oxaliplatin in particular are still commonly used today and are the focus of this thesis. As with most chemotherapy drugs, the efficacy of these drugs are limited by toxicity as well as tumour resistance, and therefore by increasing our understanding of these areas it is hoped to one day achieve personalised chemotherapy. The use of ICP-MS in the study of bio-sciences is still relatively new, however it has the ability to provide robust, fast and accurate methods for the quantification of platinum in biological samples. The research presented here utilised mass spectrometry in the study of the formation of Pt-DNA adducts in the clinical samples, the binding of oxaliplatin to short peptides and the effect of selenium supplementation on oxaliplatin in colorectal cancer cell lines. A comparison in the number of Pt-DNA adducts in saliva and leukocyte samples obtained from patients undergoing Pt-based chemotherapy demonstrated a lack of correlation between the two sample types. Samples were taken pre- and post-treatment and analysed via SF-ICP-MS and significant inter-patient variability was observed as expected. In both leukocyte and saliva samples, not only was Pt from previous chemotherapy cycles observed, but Pt was detected in the DNA in both sample types 1 hour after treatment. However a lack of correlation between platinum levels seen in the blood and saliva, combined with unexpected difficulties obtaining patient adherence to the saliva sampling protocol, indicated that saliva does not at present offer a reliable alternative to leukocytes for this assay. The binding of oxaliplatin to short nitrogen and sulfur rich peptides was investigated. Platinum binding to the peptides was observed and no significant differences in the level of binding were observed between the range of N and S rich peptides studied in this investigation. Partly due to the inability to reproduce biological conditions in this study, oxaliplatin was observed as a whole molecule, and furthermore dimers and multimers were also observed. The effect of selenium supplementation on the total cellular uptake of platinum was investigated in cultured cells via ICP-MS and LA-ICP-MS. It was observed that selenium decreased the amount of Pt taken up by the cancer cells. This was seen in analysis of populations of cells as well as by single cell analysis. Furthermore, while problems were encountered measuring selenium in subcellular experiments, the effect of selenium on the subcellular distribution of platinum as well as the number of Pt-DNA adducts could be determined.

Malware or malicious code is design to gather sensitive information without knowledge or permission of the users or damage files in the computer system. As the use of computer systems and Internet is increasing, the threat of malware is also growing. Moreover, the increase in data is raising difficulties to identify if the executables are malicious or benign. Hence, we have devised a method that collects features from portable executable file format using static malware analysis technique. We have also optimized the important or useful features by either normalizing or giving weightage to the feature. Furthermore, we have compared accuracy of various unsupervised learning algorithms for clustering huge dataset of samples. So once the clusters are created we can use antivirus (AV) to identify one or two file and if they are detected by AV then all the files in cluster are malicious even if the files contain novel or unknown malware; otherwise all are benign.

Neste trabalho desenvolvemos um procedimento simples para a separação de nanoesferas ocas de carbono (do inglês Carbon Spherical Shells ou CSS) em diâmetros entre 400 e 500 nm utilizando centrifugação corroborado pelas análises realizadas na microscopia eletrônica de varredura e de transmissão. A análise de sua composição química, realizada através da técnica de fotoelétrons excitados por raios X, indicou que as CSS são constituídas de 79% de carbono e 21% de oxigênio em sua superfície, apresentando grupos funcionais carbonila e hidroxila. Plataformas sensoriais distintas foram obtidas formando filmes homogêneos das CSS sobre o eletrodo de carbonno vítreo GCE (do inglês glassy carbon electrode ou GCE). Como resultado dos experimentos eletroanalíticos, observou-se o aumento da sensitividade do eletrodo GCE/CSS de acordo com a diminuição do diâmetro (500 até 400 nm) das CSS. As plataformas sensoriais GCE/CSS com 400 nm de diâmetro apresentaram maior sensitividade (0.02 &mu;A µmol L-1) com um limite detecção de 0.2 &mu;mol L-1. Os eletrodos GCE/CSS foram estáveis, apresentando pequena interferência de espécies concomitantes presentes na amostra e seu desempenho na quantificação de paracetamol em suor mostrou-se estatisticamente equivalente ao método padrão baseado em cromatografia líquida. / We applied a simple strategy, based upon centrifugation, to separate carbon spherical shells (CSS), in sizes varying from 400 to 500 nm, which is shown by the micrographs obtained in the Scanning and Transmission Electron microscopy analysis. In their surface, carbonyl and hydroxyl groups were present, constituting a composition of 21% of oxygen and 79% of carbon. The CSS were casted on a glassy carbon electrode\'s (GCE) surface, forming a thin film, and the resulting platform was used as a sensor. A trend was observed in the results obtained by the electroanalytical experiments: as the size of the CSS were reduced, the sensibility of the GCE/CSS platform towards paracetamol detection increased. The best attained result, namely the platform with the GCE and the 400 nm diameter CSS, have shown promising results, achieving sensitivity\'s value of 0.02 &mu;A &mu;mol-1 L. The proposed sensors were stable, displaying little interference from another species coexisting in the samples, and its performance towards paracetamol detection were statistically identical to the standard method for paracetamol detection based upon liquid chromatography.

Este trabalho teve como objetivo avaliar os efeitos de diferentes doses de radiação gama no crescimento de Alternaria alternata e na produção das toxinas Alternariol (AOH) e Alternariol Monometil Éter (AME), em amostras de cereais. Como resultado, nos grãos de arroz e nas sementes girassol observou-se diminuição do número de UFC/g, proporcionalmente à dose de radiação utilizada. Nos grãos de trigo e milho, o aumento da dose, resultou-lhes aumento das UFC/g. A análise micotoxicológica revelou, nos grãos de trigo e sementes de girassol, menor produção de AOH. Já nos grãos de arroz e milho, o grupo irradiado com 5 kGy, foi o que mais produziu AOH. Resultado semelhante foi constatado em relação à produção de AME. A microscopia eletrônica de varredura possibilitou a visualização de alterações estruturais provocadas pelas diferentes doses de radiação gama. A análise dos padrões das toxinas AOH e AME irradiados, não sofreu alterações. / The present study aimed to evaluate the effects of different gamma irradiation doses on the growth of Alternaria alternata and on production of mycotoxins Alternariol (AOH) and Alternariol Monomethyl Ether (AME) in cereal samples. The results showed a significant reduction in the number of CFU/g in rice grains and sunflower seeds, which were proportional to radiation dose used. However, in corn and wheat grains was observed an increase in the number of CFU/g with the increase of gamma irradiation. The radiation doses used resulted in a reduction of AOH levels. In rice and corn grains, the production of AOH was highest in the group irradiated with 5 kGy. Similar result was obtained with relation to AME. Scanning electron microscopy made it possible to visualize structural alterations on A. alternata induced by the different g-radiation doses used. Analysis of irradiated AOH and AME toxins standards didn´t show any alteration comparing to the control group.

A técnica analítica mais utilizada para o monitoramento de exposição a metais tóxicos ou para avaliação de deficiência a elementos essenciais é a espectrometria de absorção atômica chama (FAAS) ou com forno de grafite (GF AAS). Entretanto, cada vez mais os laboratórios de pesquisa na área clínica estão mudando seus métodos de análise, baseados nestas técnicas, para a utilização da espectrometria de massas com plasma acoplado (ICP-MS). Isso vem acontecendo porque o ICP-MS permite a determinação de elementos químicos, em diversas matrizes, numa ampla faixa de concentração (ng L-1 a mg L-1), além de possibilitar alta rapidez de análise, capacidade multielementar e limites de detecção menores que outras técnicas analíticas. Uma das principais características do método a ser utilizado para a análise de elementos químicos em rotina por ICP-MS é que ele seja rápido, com o mínimo de manipulação da amostra. Neste sentido, métodos que propõem a análise direta de amostra são mais atrativos. Todavia, ainda é limitado o número de métodos que propõem análise direta de fluidos biológicos por ICP-MS. Neste sentido, o presente trabalho teve como objetivo o desenvolvimento de um método para análise direta de sangue por ICP-MS para determinação de Ag, As, Cd, Co, Mn, Ni, Pb e Se. Para isso, amostras de sangue (200 µL) foram misturadas com 500 µL de hidróxido de tetrametilamônio (TMAH) (10% v/v) e incubadas por 10 minutos. Posteriormente, a solução resultante foi diluída para 10 mL com uma solução contendo 0,05% m/v EDTA; 0,005% v/v Triton® X-100. Em seguida, as amostras foram analisadas diretamente por ICP-MS (ELAN DRC II). Ródio (Rh) foi usado como padrão interno e a calibração das amostras foi feita por meio de ajuste de matriz com sangue base ovino. Os limites de detecção (LD) do método foram de 0,008; 0,02; 0,004; 0,009; 0,003; 0,09; 0,04; 0,1 µg L-1 para Ag, As, Cd, Co, Mn, Ni, Pb and Se, respectivamente. A validação dos resultados foi realizada com análise de um material de referência de sangue do Programa de Proficiência do Institut National de Santé Publique du Quebec, no Canadá. Validação adicional foi obtida pela comparação dos resultados obtidos pela análise de 20 amostras de sangue pelo método proposto e pela técnica de GF AAS. O método foi também comparado a outros dois existentes na literatura e comumente utilizados em laboratórios dos Estados Unidos e Suécia, apresentando limites de detecção comparáveis ou melhores e melhores exatidão e precisão. / The most used analytical technique for monitoring the exposure to toxic metals or for the assessment of the deficiency of essentials elements is the atomic absorption spectrometry with flame (FAAS) or graphite furnace (GF AAS). However, more and more clinical laboratories are changing their methods of analysis, based on this technique, to methods using inductively coupled plasma-mass spectrometry (ICP-MS). It occurs because ICP-MS allows the determination of chemical elements in various types of samples, at concentrations in a wide linear range (ng L-1 to mg L-1), providing high-throughput analysis with multielemental capability with lower detection limits. However, for routine porpuses the method of choice must be fast with minimal sample manipulation.On the other hand, the number of methods proposing direct introduction of biological fluids to the ICP-MS are still limited. This work aimed the development of a method for the direct analysis of blood samples by ICP-MS for the determination of Ag, As, Cd, Co, Mn, Ni, Pb and Se. For this, blood samples (200 L) were mixed with 500 L of tetramethylammonium hydroxide (TMAH) (10% v/v) and left at room temperature during 10 minutes. Subsequently, the resulting solution was diluted to 10 mL with a solution containing 0.05% m/v EDTA + 0005% v / v Triton ® X-100. Thus the samples were analyzed directly by ICP-MS (ELAN DRC II). Rhodium (Rh) was used as internal standard with matrix matching calibration. The method detection limits were: 0.008, 0.02, 0.004, 0.009, 0.003, 0.09, 0.04, 0.1 µg L-1 for Ag, As, Cd, Co, Mn, Ni , Pb, and Se respectively. Method validation was acquired with the analysis of blood reference material provided by the Institut National de Santé Publique du Quebec, Canada. Furthermore, for additional validation 20 ordinary blood samples were analyzed by the proposed method and by GF AAS. The method was also compared with two existing methods in the literature and commonly used in laboratories in the United States and Sweden where comparable or better detection limits and better accuracy and precision were obtained.

A interpretação dos achados laboratoriais no estabelecimento da causa mortis consiste na integração dos conhecimentos sobre a toxicocinética e toxicodinâmica do agente, conhecimentos de sua redistribuição post mortem (RPM) e achados necroscópicos que possibilitem o nexo causal entre o toxicante e o efeito letal. Neste sentido, é importante considerar que somente as concentrações de cocaína (COC) e seus metabólitos podem não ser determinantes na interpretação da causa de morte, podendo ser útil o cotejamento com outros parâmetros, como os níveis de neurotrasmissores que representem o mecanismo de ação do fármaco. Assim, este trabalho teve por objetivo investigar a RPM da COC e seu metabólito benzoilecgonina (BE) em três segmentos do tecido encefálico (TE), no humor vítreo (HV) e sangue (SG), bem como determinar as concentrações de catecolaminas e indolaminas no encéfalo para avaliar a aplicação da neuroquímica post mortem (NPM) na toxicologia forense. No estudo de RPM foram quantificados os níveis de COC e BE em três segmentos do TE (córtex frontal, núcleos da base e cerebelo), no HV e no SG através de método por cromatografia líquida de alta eficiência (HPLC) acoplada ao detector de arranjo de diodos. Os estudos de neuroquímica foram realizados empregando-se HPLC acoplada ao detector eletroquímico. Os resultados indicaram que as concentrações médias de COC foram maiores no TE, seguido por SG e HV (3,09, 2,92 e 1,71 &#181;g/mL, respectivamente), enquanto para BE foram maiores em SG, seguido por HV e TE (6,12, 1,39 e 0,87 &#181;g/mL, respectivamente). As concentrações de COC se apresentaram distribuídas uniformemente nos três segmentos de TE e apresentaram alta correlação com o HV. Adicionalmente, a média de concentrações de dopamina total foi maior no grupo de indivíduos com amostras positivas para COC, sendo verificado diferença significativa entre este grupo e o de indivíduos com amostras negativas para o fármaco de interesse. Os resultados demostraram que o estudo de RPM e da NPM constituem ferramentas aplicáveis na interpretação da causa e maneira de morte. / In case of intoxication, the interpretation of analytical results to assess the cause and process of death requires knowledge about toxicokinetics, toxicodynamic, postmortem redistribution, and autopsy elements. Cocaine-related deaths occur mainly after prolonged drugs use and the presence of cocaine (COC) in fluids or tissues does not prove that death was due to COC consumption, and the interpretation of postmortem concentrations is even more complicated than attempts at making such correlations in the living. The objectives of this study were to investigate the post mortem redistribution (PMR) of COC and its metabolite benzoylecgonine (BE) in three segments of brain (frontal cortex, base nucleous, and cerebellum), vitreous humor, and blood. In additional, catecholamines and indolamines were quantified in brain in order to evaluate the usefulness of post mortem neurochemistry (PMN) in forensic toxicology. In PMR studies were quantified the COC and BE levels in three brain (BR) segments, in vitreous humor (VH), and blood (BL) by High Performance Liquid Chromatography (HPLC) with diode array detection, and for neurochemistry studies the neurotransmitters were quantified by HPLC with electrochemical detection. A homogenous distribution of COC and BE within frontal cortex, base nucleous, and cerebellum was found. The COC media concentrations were 3.09, 2.92 e 1.71&#181;g/mL in BR, BL and VH, respectively, and the BE media concentrations were 6.12, 1.39 e 0.87 &#181;g/mL in BL, VH, and BR, respectively. The COC concentrations in VH show high correlation with brain. The media total dopamine concentration was significant higher in COC positive group. These findings suggest that the studies of PMR and PMN by neurotransmitters levels may be useful to assess the cause and process of death.

Orientador: Pedro de Magalhães Padilha / Banca: Lincoln Carlos Silva de Oliveira / Banca: Paulo Roberto Rodrigues Ramos / Abstract: This paper presents a simple, fast and sensitive method to determine chromic oxide (used as a biological marker of fish feed) in samples of fish feces by GFAAS through the direct introduction of slurries of the samples into the spectrometer's graphite tube. The standard samples of feces and of fish feed containing 0.10 to 1.00 mg kg-1 of Cr2O3 were pre-frozen for 1 minute in liquid nitrogen and then ground a cryogenic mill for 2 minutes, which reduced the samples' grain size to less than 60 æm. The standard slurries were prepared by mixing 20 mg of standard samples of fish feed or feces with 1 mL of a solution containing 0.05 % v/v of Triton X-100 and 0.50 % v/v of suprapure HNO3 directly in the spectrometer's automatic sampling glass. The final concentrations of Cr2O3 present in the standard slurries were 2, 4, 8, 16 and 20 g L-1. After sonicating the mixture for 20 seconds, 10 L of standard slurries were injected into the graphite tube, whose internal wall was lined with a metallic palladium film that acted as a permanent chemical modifier. The limits of detection (LOD) and quantification (LOQ) calculated for 20 readings of the blank of the standard slurries (2% m/v of feces or feed devoid of minerals) were 0.81 and 2.70 g L-1 of Cr2O3 for the standard feces slurries, 0.84 and 2.83 g L-1 of Cr2O3 for the standard feed slurries. The proposed method was applied in studies of nutrient digestibility of different fish feeds and its results proved compatible with the results obtained from samples pre-mineralized by acid digestion. / Resumo: No presente trabalho um método simples, rápido e sensível é proposto para determinação de crômio (utilizado como marcador biológico de rações de peixes) em amostras de fezes de peixes por GFAAS utilizando-se a introdução direta de suspensões das amostras no tubo de grafite do espectrômetro. Amostras de fezes e de rações contendo de 0,10 a 1,00 mg kg-1 de Cr2O3 (isentas de minerais) foram moídas em moinho criogênico. Após este procedimento as amostras apresentaram granulometria menor que 60 m. As suspensões foram preparadas misturando-se, diretamente no copo do amostrador automático do espectrômetro, 20 mg de amostras de ração, ou fezes, com 1 mL de solução contendo 0,005% v/v de Triton X-100 e 0,50% v/v de HNO3 suprapuro. Após sonificação durante 20 segundos, 10 L de suspensão foram injetados para dentro do tubo de grafite que continha, na sua parede interna, uma película de paládio metálico que atuou como modificador químico permanente. Os limites de detecção (LOD) e de quantificação (LOQ), calculados em relação a 20 leituras do branco das suspensões (2% m/v de fezes ou ração isentas de minerais), foram de 0,81 e 2,70 g L-1 de Cr2O3 para as suspensões padrão de fezes, 0,84 e 2,83 g L-1 de Cr2O3 para as suspensões padrão de ração. O método proposto foi aplicado em estudos de digestibilidade/disponibilidade de nutrientes em diferentes rações de peixes e mostraram-se de acordo com os resultados obtidos, utilizando-se amostras previamente mineralizadas por digestões ácidas. / Mestre

O uso das amostragens ambientais para fins de salvaguardas vêm sendo aplicadas pela Agência Internacional de Energia Atômica AIEA desde 1996 e estão sendo rotineiramente utilizadas como uma medida de fortalecimento complementar aos procedimentos tradicionais de salvaguardas de materiais nucleares. O intuito é verificar se os Estados signatários aos acordos de salvaguardas não estão divergindo suas atividades nucleares pacíficas para atividades nucleares não declaradas. O presente trabalho apresenta um novo protocolo de coleta e análise de esfregaços para identificação de assinaturas nucleares que possam relacionar-se com as atividades nucleares desenvolvidas na instalação inspecionada. Neste trabalho foi utilizada como estudo de caso uma planta real de reconversão de urânio do ciclo do combustível nuclear do IPEN. A estratégia analítica proposta utiliza diferentes técnicas, como medidor de radiação alfa, MEVEDS e ICPMS para identificar assinaturas do urânio aderido ao esfregaço. Na análise dos esfregaços, foi possível identificar partículas de UO2F2 e UF4 através da comparação morfológica e análises semi-quantitativas utilizando a técnica de MEVEDS. Nesse trabalho, utilizaram-se métodos que como resultado tem-se a composição isotópica média da amostra, onde o enriquecimento (fração atômica molar) variou de 1,453 ± 0,023% a 18,24 ± 0,15% no isótopo 235U. Através das coletas realizadas externamente, uma forma não intrusiva de amostragem, foi possível à identificação de atividades de manuseio de material enriquecido com medidas de fração atômica molar de 1,453 ± 0,023% a 6,331 ± 0,055% no isótopo 235U, bem como uso de material reprocessado, através da identificação do isótopo 236U. As incertezas obtidas neste trabalho para a razão n(235U)/n(238U) variaram de 0,40% a 1,68%. / The use of environmental samplings for safeguards purposes has been applied by the International Atomic Energy AgencyIAEA since 1996 and they are routinely used as a complementary measure to strengthen the traditional nuclear safeguards procedures. The aim is verify if the signatory states to the safeguards agreements are not diverging their peaceful nuclear activities to undeclared nuclear activities. This work describes a new protocol of collect and analysis of swipe samples in order to achieve identification of nuclear signatures, which may be related to the nuclear activities developed in the inspected facility. In this work, as a case of study, a real uranium reconversion plant of the nuclear fuel cycle of IPEN was used. The strategy proposed uses different analytical techniques, such as alpha radiation meter, SEM-EDX and ICP-QMS to identify signatures of the uranium adhered to the swipe samples. In the swipe samples analysis, it was possible to identify particles of UO2F2 and UF4 through the morphological comparison and semi-quantitative analysis performed by SEM-EDX technique. The methods used in this work bring the average isotopic composition of the sample as a result, in which the enrichment (molar atomic fraction) ranged from 1.453 ± 0.023% to 18.24 ± 0.15% in the 235U isotope. Through of the external collections, a non-intrusive sampling, it was possible to identify handling activities of enriched material with molar atomic fraction of 1.453 ± 0.023% to 6.331 ± 0.055% in the 235U isotope, as well as the use of reprocessed material by means of the 236U isotope identification. The uncertainties obtained in this work to the n(235U)/n(238U) ratio varied from 0.40% to 1.68%.