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Boron treated test houses at Mississippi State University’s Dorman Lake test site in Starkville, MS were built in 1989 to investigate the effectiveness of boron treatments with exposure to natural weathering. After being undisturbed for more than 20 years, samples were taken to evaluate the remaining levels of original treatments in the test houses. Visual evaluation of the test structures, curcumin test, and ICP-MS analysis of the borate content shows borates are a capable and effective long-term treatment for wood used in construction. No appreciable damage due to termite feeding was observed. Boron was still detectable by curcumin staining and positive boron levels were confirmed by ICP-MS analysis.

In dieser Arbeit wurde ein Verfahren zur rückführbaren Proteinquantifizierung unter Verwendung von Schwefelisotopenverdünnung mit induktiv gekoppelter Plasmamassenspektrometrie (ID-ICP-MS) entwickelt. Die Methode dient zur zuverlässigen Quantifizierung laborinterner Proteinstandards. Sie eignet sich nur zur Analyse reiner Proteine, deren Stöchiometrie bekannt ist, da die Proteinkonzentration aus dem Schwefelgehalt bestimmt wird. Nicht proteingebundener Schwefel wird durch Membranfiltration von der Proteinfraktion abgetrennt und mit ID-ICP-MS quantifiziert. Der Gesamtschwefelgehalt in der Probe wird ebenfalls mittels ID-ICP-MS quantifiziert und um die Menge an ungebundenem Schwefel korrigiert. Die Optimierung der Probenvorbereitung zeigte, dass ein Aufschluss die Unsicherheit des Ergebnisses verbessert. Für die Methodenentwicklung wurden ein zertifiziertes Rinderserumalbumin-Referenzmaterial (BSA), sowie ein kommerzielles Avidin verwendet. Die Bestimmung der Proteinmassenfraktionen und Unsicherheitsbudgets erfolgte nach Korrektur für den ungebundenen Schwefel (0,4 % für BSA, 30 % für Avidin). Die Methode wurde auf das Tau-Protein angewendet, das ein Biomarker für die sogenannten „Tauopathien“ ist – eine Gruppe neurodegenerativer Krankheiten, die die Alzheimer-Krankheit und die frontotemporale Demenz einschließen. Durch Verwendung eines isotopenangereicherten Spikes, der an das SI-System angebunden ist, wurde die metrologische Rückführbarkeit für den Massenanteil des Tau-Proteins erreicht. Dieser Tau-Standard wurde zur absoluten Quantifizierung toxischer transgener Tau-Spezies in der löslichen Hirnfraktion transgener Mäuse verwendet. Die entwickelte Methode ist für die rückführbare Quantifizierung von Proteinen zur Verwendung als Standards in der biologischen und medizinischen Forschung anwendbar. Sie zeigte eine ähnliche Präzision wie etablierte Verfahren, erforderte jedoch weniger Probenvorbereitung und keine spezies-spezifischen Standards. / In this work, a method for traceable protein quantification using sulphur isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) was developed. The method is intended for the reliable quantification of in-house protein standards. It is only suited for pure protein formulations for proteins of known stoichiometry because the protein concentration is determined from the sulphur content. Non-protein bound sulphur is separated from the protein fraction by membrane filtration and is quantified by ID-ICP-MS. The total sulphur content in the sample is as well quantified by ID-ICP-MS and corrected for the amount of non-protein bound sulphur. Optimisation of the sample preparation showed that digestion improves the uncertainty of the result. For method development, a certified reference material bovine serum albumin (BSA) and a commercial avidin were used. The protein mass fractions with full uncertainty budgets were determined after correction for unbound sulphur. The developed procedure was applied to the tau protein, which is a biomarker fort he so-called „tauopathies“ – a group of neurodegenerative diseases including Alzheimer’s disease and Frontotemporal dementia. By employing an isotopically enriched spike, which is linked to the SI system, full metrological traceability was achieved for the tau mass fraction. The mass fraction of (0.328 ± 0.036) g kg-1 for tau was determined by ID-ICP-MS and confirmed by amino acid analysis. This tau standard was used for the absolute quantification of toxic transgenic tau species in the soluble brain fraction of transgenic mice. The developed method is applicable for the traceable quantification of proteins for use as standards in biological and medical research. The precision of the method was similar to established absolute protein quantification procedures while requiring less sample preparation and no species-specific standards.

Le mercure est un contaminant présent dans l'ensemble des compartiments de l'environnement et l'homme y est directement exposé via l'alimentation. Actuellement, les organismes gouvernementaux évaluent la sécurité des produits alimentaires en se basant essentiellement sur la concentration totale de cet élément. Cependant, la toxicité du mercure dépend, entre autre, de l'espèce absorbée (dont le méthylmercure, sa forme la plus toxique). Par conséquent, l'analyse de spéciation, c'est à dire la détection et quantification des différentes formes chimiques de cet élément, présente un intérêt croissant. Le principal objectif de ce projet a donc été de développer et de valider, sous assurance qualité, une méthode sensible et d'une grande exactitude, basée sur l'utilisation de la dilution isotopique. Elle sera par la suite appliquée comme méthode de référence par l'agence pour l'analyse en spéciation du mercure dans les produits de la pêche afin de permettre une meilleure évaluation des risques encourus par le consommateur. La première partie de ce travail a porté sur l'étude du cycle biogéochimique du mercure et de l'état de l'art des diverses méthodes de préparation de l'échantillon, de séparation et de quantification du Hg dans les matrices biologiques, afin d'émettre des choix analytiques. Ainsi, les principaux composés mercuriels susceptibles d'être retrouvés dans les produits de la pêche (le méthylmercure et le mercure inorganique) ont été déterminés par couplage GC-ICP-MS et une quantification par dilution isotopique. La seconde partie des travaux a été consacrée à l'optimisation de la méthode de préparation des échantillons et de la technique de quantification. Ces travaux sur différents matériaux de référence certifiés ont montré que des modifications de la distribution naturelle de l'échantillon pouvaient survenir dès l'étape d'extraction, préconisant un marquage isotopique avant extraction solide-liquide par digiPREP des espèces mercurielles et dérivation par propylation par le tétrapropylborate de sodium et agitation rotative. Les résultats expérimentaux ont été traités par dilution isotopique simple et multiple. Les teneurs obtenues ont été similaires, pour l'ensemble des matrices analysées, montrant que peu ou pas de transformation inter-espèces surviennent au cours de la procédure analytique. Une quantification par double marquage isotopique et dilution isotopique simple a donc été conservée. L'évaluation des critères analytique a démontré que la méthode est validée pour la spéciation du mercure dans les produits de la pêche, selon les normes françaises AFNOR NF V03-110 de 1998 et de 2010. La dernière partie des travaux a porté sur l'application de la méthode validée à la spéciation du mercure dans des échantillons biologiques réels, ainsi qu'à la participation à plusieurs essais interlaboratoires d'aptitudes organisés par le CSL-FAPAS sur un échantillon de thon en conserve et par l'IRMM sur le matériau IMEP-109 de homard. / Mercury is a contaminant which is found in all compartments of the environment and to which human beings are directly exposed when eating food. Government agencies assess the safety of food products by using total mercury concentrations. However, its toxicity depends on the species absorbed (among which methylmercury is its most toxic form). Therefore, the analysis of speciation, i.e. detection and quantification of different chemical forms of this element, is of high interest. The main objective of this project was to develop and validate, under quality assurance, a sensitive and highly accurate method, based on the use of isotope dilution. This method will then be applied as a reference method by the agency for speciation analysis of mercury in seafood, in order to better assess risks to the consumer. The first part of this work focused on the biogeochemical cycle of mercury and the state of art of the various methods of sample preparation, separation and quantification of Hg in biological matrices in order to make analytical choices. Thus, mercury compounds (methyl mercury and inorganic mercury) were determined by gas chromatography (GC) coupled with an inductively coupled plasma mass spectrometer (ICP-MS) and quantified by isotope dilution. The second part of the work was dedicated to the optimization of the method of sample preparation and the quantification technique. The work was made on different certified reference materials and showed that changes of the natural distribution of the sample could occur during the extraction step. Therefore, isotopic tracers had been added to the sample before this step. Mercury species were extracted by a solid-liquid extraction by using a digiPREP and derivated by propylation using tétrapropylborate the sodium and a rotary agitation. Data were treated by simple and multiple isotope dilution. Achieved concentrations were similar for all analyzed matrices. Results showed that inter-species transformation hardly occurred during the analytical procedure. This was the reason why the use of two isotopic tracers for quantification by simple isotope dilution was kept. To end, the method was validated for the speciation of mercury in seafood, in respect with the French norms AFNOR NF V03-110 of 1998 and 2010. Finally, the work ended with the applicability of the validated method for mercury speciation analysis in real biological samples and our participation in several inter-laboratory proficiency tests organized by the CSL-FAPAS on a sample of tuna and by the IRMM on the material IMEP-109 (lobster).

[pt] Diferentes métodos espectrométricos de análise, incluindo ICP OES, ICP-DRCMS e Q-ICPMS com técnicas hifenadas (geração de hidreto, vaporização eletrotérmica ou cromatografia de íons), foram aplicados na caracterização química de 16 óleos e 41 amostras de efluentes aquosos de uma refinaria de petróleo. O objetivo específico deste estudo foi o de entender o comportamento do selênio (Se) e de suas espécies químicas ao longo do processo de geração e tratamento dos efluentes desta unidade industrial. A caracterização química multielementar das amostras por ICP-MS revelou uma composição muito complexa da maioria deles, com altas salinidades e potenciais interferentes espectrais e não espectrais presentes. Por isso, foi necessária uma reavaliação crítica das técnicas analíticas para a determinação de Se e de suas espécies. As técnicas de ICP-DRC-MS, utilizando CH4 como gás de reação, e de ETVICPMS mostraram o seus potencial para a determinação de Se com melhores limites de detecção (cerca de 0,05 ug L-1 para ambas), mas também as suas limitações na análise de efluentes com altas salinidades. Nas 16 amostras de petróleo analisadas, verificou-se uma grande variabilidade nas concentrações de Se total, cobrindo uma faixa de < 10 ug kg-1 até 960 ug kg- 1, a qual poderia explicar também a carga muito variável deste elemento nos efluentes das diferentes unidades de tratamento. As maiores concentrações de Se total foram encontradas nas águas ácidas, com concentrações de até 1714 ug L-1. Confirmou-se a predominância de SeCN - na maioria das amostras analisadas, mas observaram-se também outras espécies com tempos de retenção diferentes das espécies Se(IV), Se(VI) e SeCN-, especialmente nos efluentes da estação de tratamento de despejos industrais (E.T.D.I.). Em amostras ácidas, identificou-se Se coloidal (Seº) formado pela decomposição de SeCN-, ou de outras espécies pouco estáveis nestas condições. Experiências de bancada com soluções de SeCN- apoiaram esta hipótese. Foi constatada, que o perfil de especiação de amostras coletadas num mesmo local de processamento, mas em épocas diferentes, pode variar significativamente, o que torna difícil a comparação de dados obtidos neste trabalho com os de outros autores. / [en] Different spectrometric methods of analysis, including ICP OES, ICP-DRC-MS and Q-ICP-MS, the latter hyphenated to hydride generation, eletrothermal vaporization or ion chromatography have been appliesd to the chemical characterization of 16 crude oils and 41 effluents samples from a petroleum refinery. The specific objective of this study was to get information on the behavior of selenium (Se) and its species along the different processes of generation and treatment of the effluents.Multielemental characterization of effluents by ICP-MS revealed a complex composition of most of them, with high salinity and potential spectral and non spectral interferents present. For this reason, a critical reassessment of the analytical techniques for the determination of total Se and its species was necessary. DRC-ICP-MS and ETV-ICPMS, using CH4 as cell reaction gas, showed their potential for the determination of Se with better detection limits (about 0,05 ug L-1), but also their limitations for the analysis of effluents with high salinity. A large variability in the concentration of Se was observed in the 16 analysed crude oil samples (< 10 ug kg-1 Se until up to 960 ug kg-1), which may explain also the varying concentrations measured in the effluents. Highest concentrations of selenium were measured in samples from the treatment unit for acid waters (up to 1.714 ug L-1). The predominance of selenocyanate (SeCN-1) was confirmed in most of the effluent samples analysed, but also several other species with retention times different from Se(IV), Se(VI) e SeCN - were observed, especially in samples from the treatment plant. Colloidal Se (Seº) was identified in acid waters, probable formed by decomposition of SeCN - or other unstable species under these conditions. Laboratory experiments with selenocyanate solutions confirmed this hypothesis. The speciation profile of samples collected at the same point, but at different time intervals, showed significant variations, not allowing easy comparison of the results obtained in this work with those of other authors.

O arsênio é um dos mais tóxicos elementos químicos e reconhecidamente carcinogênico. Ele pode ser encontrado em alimentos basicamente em 5 formas: arsenobetaína (AsB), dimetil-arsênio (DMA), monometil-arsênio (MMA), arsenato (As5+) e arsenito (As3+), sendo estas duas últimas (As-i) as mais tóxicas. Assim, é de suma importância a utilização da especiação química de As para avaliação dos reais riscos associados à ingestão de alimentos contaminados. Neste sentido, o presente trabalho teve como objetivos o desenvolvimento de um método para separação das espécies de As por LC e detecção por ICP-MS; extrações quantitativas das espécies de As de tecidos animais e em grãos de arroz; aplicação dos métodos em amostras de alimentos consumidos no Brasil; e estudo do metabolismo do As em diferentes cultivares de arroz. O método desenvolvido para a extração das espécies de As em tecidos animais (ovo, músculos de ave, peixe e boi, etc.) utilizou apenas metanol (10%v/v) e ácido nítrico (2%v/v) como extratores e 2 minutos de sonicação, mostrando recuperação quantitativa do analito (>88%, n=3) pela análise dos materiais de referência (CE278, DOLT-3, DORM-3 e SRM NIST 1577). No entanto, para a análise de arroz, apenas ácido nítrico 2%v/v foi utilizado como extrator, possibilitando uma recuperação quantitativa (>94%, n=6), quando da análise do material de referência (NIST Rice Flour 1568a). Para a separação cromatográfica foram avaliadas diversas colunas, das quais a troca aniônica (Hamilton PRP-X100®) foi utilizada em todos os experimentos. A aplicação dos métodos na análise de alimentos diversos consumidos no Brasil mostrou uma grande variação nas concentrações das diferentes espécies do arsênio em músculos, ovos e, especialmente, no arroz. Devido as altas concentrações de As encontradas em amostras de arroz comercializadas no Brasil (em vários casos com predominância das espécies mais tóxicas, As3+ e As5+) e ao grande consumo deste alimento no país e no mundo, foi também realizado um estudo de metabolismo do As em 6 diferentes cultivares. O foco deste estudo foi a síntese de fitoquelatinas (PCs), compostos não peptídicos produzidos por plantas expostas a elementos tóxicos, e sua influência no fator de transferência (TF) do As solo-grãos. O TF do As, assim como a concentração das PCs, variaram em relação aos cultivares (genótipos) estudados. Além disso, as PCs mostraram ter uma forte correlação positiva entre si e com a concentração de As-i nos grãos, bem como uma correlação negativa do TF do As raízes-grãos. Portanto, os métodos desenvolvidos demonstraram fácil aplicação em rotina para avaliação toxicológica dos alimentos em relação às espécies de As e, finalmente, o estudo de metabolismo do As pela planta do arroz pode contribuir para escolha de cultivares que o absorvam menos, reduzindo sua ingestão frente ao consumo de arroz. / Arsenic is one of the most toxic chemicals and known carcinogen. It can be found in food basically in 5 different forms: arsenobetaine (AsB), dimethyl arsenic (DMA), monomethyl arsenic (MMA), arsenate (As5+) and arsenite (As3+), the latter two forms (i-As) are the most toxic. Thus, it is of extreme importance the use of chemical speciation for the evaluation of the real risks associated to arsenic intake from contaminated food. In this sense, this study aimed develop a simple method for separation of arsenic species by LC and detection by ICP-MS, quantitative extraction of arsenic species from animal tissues and rice grains, the application of the proposed method in the analysis of food samples commercialized in Brazilian markets, and the study of arsenic metabolism in different rice cultivars. The method developed for the extraction of arsenic species in animal tissues (egg, muscle of chicken, fish and cattle, etc.) used only methanol (10%v/v) and nitric acid (2%v/v) as extractant and 2 minutes of sonication, showing quantitative recovery of the analyte (>88%, n=3) when analyzing reference materials (CE278, DOLT-3, DORM-3 e SRM NIST 1577). However, for the analysis of rice grains, only nitric acid (2%v/v) was used as extractant, allowing a quantitative recovery (>94%, n=6), when analyzing the reference material (NIST Rice Flour 1568a). For the chromatographic separation several columns were evaluated and an anion exchange column (Hamilton PRP X-100) was used in all experiments. The analysis of several foods consumed in Brazil, showed a wide variation in the concentrations of different arsenic species in muscle, eggs, and especially in rice. Due to the high concentrations of arsenic found in rice samples (in several cases with predominance of more toxic species, As3+ and As5+) and the large consumption of this food in the country and abroad, it was also carried out a study on arsenic metabolism in 6 different rice cultivars. The focus of this study was the synthesis of phytochelatins (PCs), non-peptide compounds produced by plants exposed to toxic elements, and its influence on the transfer factor (TF) soil-grains. The TF of arsenic as well as the concentration of PCs varied in relation to the cultivars (genotype) studied. Furthermore, the PCs have shown a strong positive correlation between themselves and with the concentration of i-As in the grains, and a negative correlation with TF roots-grains. Therefore, the developed method demonstrated feasibility for routine use in toxicological studies of arsenic species in food samples and, finally, the study of arsenic metabolism in rice plant can contribute to the selection of cultivars that absorb less arsenic, thereby reducing the intake of this toxic element by rice consumption.