Propõe-se, pela primeira vez, a associação do tratamento fotocatalítico de amostra, direcionado à degradação e/ou eliminação de interferentes orgânicos, com a separação analito/matriz via geração de hidretos voláteis seguida de determinação por espectrometria de absorção atômica (HG-AAS). O fotocatalisador TiO2 (P-25) foi utilizado sempre em suspensão na amostra, e como fonte de radiação UV empregou-se lâmpada de mercúrio. Duas geometrias de reator fotocatalítico foram examinadas: irradiação estacionária de amostras contidas em cubetas de quartzo (3,5 mL); e irradiação em reator tubular constituído de bobina de Teflon montada em torno da lâmpada. Para avaliar a eficiência do tratamento sob diferentes condições, utilizou-se inicialmente o sistema-modelo Cd(II)-EDTA, com detecção do Cd(II) não quelado por voltametria de pulso diferencial em eletrodo de gota pendente de mercúrio, sabidamente não influenciada pelo TiO2 em suspensão. Nos estudos com HG-AAS, focalizou-se a aplicação do tratamento fotocatalítico à decomposição da arsenobetaína (Asb), um composto modelo interessante por ser refratário aos tratamentos convencionais (micro-ondas + digestão ácida). As condições selecionadas para a etapa de HG-AAS foram: concentração de HCl, 3 mol.L-1, concentração de NaBH4, 1% m/v em NaOH 0,1 mol.L-1, volume de amostra, 0,10 mL e temperatura do atomizador de tubo de quartzo, 980 °C. Nessas condições, as curvas de calibração obtidas por HG-AAS para As(III) e As(V) na faixa de 0,020 a 0,100 mg.L-1 (20 a 100 ppb) apresentaram linearidade e sensibilidade próximas, indicando eficiência de formação similares, característica esta favorável à quantificação total de arsênio em aplicações futuras a amostra reais. Estudos preliminares mostraram que a taxa de recuperação do arsênio é maior no tratamento fotocatalítico realizado em meio alcalino, (pH=12) em razão da menor tendência à adsorção de arsênio em TiO2 nesse meio frente ao neutro e ácido. Parâmetros como o tempo de irradiação, concentração do fotocatalisador e de Asb, além da influência de O2 molecular como scavenger de elétrons também foram investigados. Nas condições selecionadas, partindo-se de uma solução de Asb 0,075 mg.L-1 em arsênio, alcançou-se recuperação aproximada de 80% mediante irradiação por 15 minutos e de 100% após 45 minutos. A decomposição da Asb pelo método fotocatalítico proposto foi confirmada por espectrometria de massa com ionização por electrospray e estudos adicionais poderão revelar se as espécies de arsênio envolvidas na geração da arsina encontram-se completamente mineralizadas. / The combination of photocatalytic sample preparation, aiming degradation of organic interferences, with analyte/matrix separation by generation of volatile hydrides followed by atomic absorption spectrometric determination (HG-AAS) is proposed for the first time in this work, mainly devoted to the investigation of total arsenic analysis. A mercury lamp served as source of UV-radiation and the photocatalyst, TiO2 (P25), was used as a suspension in the sample solution. Two geometries of photocatalytic reactor were examined: stationary irradiation of a set of samples contained in 3.5 mL quartz cuvettes (preferred one for the present application) and stopped-flow irradiation of a sample in a tubular reactor consisting of a Teflon tube coiled around the lamp. Evaluation of the digestion efficiency of the reactors under different conditions was made with help of the model system Cd(II)-EDTA, with detection of the unchelated Cd(II) by differential pulse voltammetry with the hanging mercury drop electrode, known to work in the presence of TiO2 suspension. The subsequent studies in combination with HG-AAS focused on the photocatalytic degradation of arsenobetaine (Asb), chosen as a model because it is particularly resistant to conventional treatments (microwave + acid digestion). The following conditions were established for the HG-AAS step: HCl concentration (3 mol.L-1) and NaBH4 concentration (1% m/v in NaOH 0,1 mol.L-1), sample volume (0.10 mL) and atomization temperature (980 °C). Calibration curves for As (III) and As (V) by HG-AAS in the range of 0,020 to 0,100 mg.L-1 (20 a 100 ppb) conveyed in slope and linearity, indicating the same efficiency of arsine formation from both species, favoring the total quantification of arsenic in the sample. Alkaline medium (pH=12) was preferred for the photocatalytic digestion because recoveries of arsenic were better than in neutral or acidic medium, possibly due to lower losses by adsorption of arsenic species on TiO2. The effects of parameters such as irradiation time, concentration of the photocatalyst and of arsenobetaine, as well as the influence of molecular O2 as an electron scavenger were investigated. Under selected conditions and for a starting solution of 0,075 mg.L-1 Asb an arsenic recovery of 80% approximately was obtained after 15 minutes of irradiation while full recovery required 45 minutes. The decomposition of the Asb molecule after irradiation was confirmed by electrospray mass spectrometry and a further study may reveal if the arsenic species involved in the arsine generation are fully mineralized ones.

De nombreux produits chimiques se retrouvent dispersés dans l'environnement avec des conséquences parfois néfastes pour les hommes et les écosystèmes. Parmi ces substances figurent les antibiotiques et les stéroïdes hormonaux. Peu de données sont disponibles quant à la présence et le devenir de ces substances dans l'environnement notamment pour le sol, par manque de méthodologies. Nous avons donc mis au point des procédures d'analyse de traces de ces contaminants émergents, dans l'eau et le sol. Nous avons développé des méthodes multi-résidus et inter-familles basées sur des analyses LCMS/ MS. Pour les échantillons aqueux, l'extraction est menée sur phase solide (SPE, OASIS HLB). Les MLQs sont comprises entre 0.09 et 34 ng/L. Pour la matrice solide, la procédure d'extraction est inspirée de la méthode appelée QuEChERS suivie d'une purification SPE. Elle a été validée et des MLQs entre 0.013 et 3 ng/g ont été atteintes. Les tétracyclines et les fluoroquinolones, ont été étudiées séparément car elles ont des propriétés physico-chimiques bien spécifiques les rendant difficiles à extraire correctement du sol avec une méthode inter-familles. La méthode développée sur la matrice sol a permis une étude statistique mettant en exergue l'impact de certains paramètres du sol sur les rendements d'extraction et les effets matrice. Les méthodes ont été appliquées à une étude en colonnes de sol pour obtenir des données sur le transfert, l'accumulation et la dégradation des composés dans le sol / Several chemical products are dispersed in the environment and the consequences can be sometimes harmful for humans and the ecosystems. Among these substances appear the antibiotics and the hormonal steroids. Nowadays, only few data are available on the presence and the fate of these substances in the environment in particular for solid matrices, mainly due to a lack of methodologies. Consequently, methods to analyze traces of « emergent » contaminants in water and soil were carried out. Therefore, multi-residues and inter-families procedures based on LC-MS/MS analysis were established. Concerning the aqueous samples, 23 analytes are extracted with the SPE technique (OASIS HLB). MLQs are between 0.09 and 34 ng/L. For the solid matrix, the extraction procedure of 31 compounds is inspired from the method called QuEChERS and followed by a purification step. This methodology was validated and MLQs between 0.013 and 3 ng/g were obtained. Two antibiotics families, tetracyclines and fluoroquinolones, were studied separately as they have specific physical/chemical properties and are therefore difficult to extract from soil with an inter-families method. Then, the method developed for the soil matrix allowed a statistic study which showed the impact of the soil parameters on the recoveries and matrix effects. Finally, the methodologies were applied to a soil column study which allowed obtaining data on the transfer, accumulation and degradation of the substances in soil

Les travaux décrits dans ce mémoire ont pour objectif d'imager des cellules par des techniques d'imagerie complémentaires à la spectroscopie de fluorescence : la micro-spectroscopie Raman et l'imagerie NanoSIMS. Le présent manuscrit se divise en quatre chapitres et présente les différents aspects menant à la mise en place de ce projet. Le premier chapitre du manuscrit a pour but de positionner le projet d'un point de vue biologique. Ce chapitre présente l'organite que nous souhaitions marquer, le nucléole, et la façon dont nous avons procédé à sa localisation par l'intermédiaire de sondes moléculaires. Le marquage que nous avons choisi est un immuno-marquage indirect faisant intervenir deux anticorps : un anticorps primaire spécifique à la nucléophosmine, protéine majoritairement présente dans le nucléole et un anticorps secondaire, reconnaissant l'anticorps primaire, marqué par une sonde moléculaire d'intérêt. Ce chapitre a également permis de montrer par une analyse en immunofluorescence l'absence d'interférence des sondes moléculaires dans le cadre de ce marquage. Le second chapitre se focalise sur la synthèse des sondes moléculaires permettant le marquage des anticorps secondaires. Les sondes envisagées pour ce marquage possèdent un groupement ester de succinimide réactif capable de "s'accrocher" de manière covalente aux fonctions amines de l'anticorps secondaire et un ou plusieurs groupements fonctionnels visible par la technique d'imagerie voulue. Trois catégories de sondes ont été préparées et dépendent de la technique d'imagerie employée. Les sondes Raman comportant une triple liaison carbone-carbone visible par cette technique, les sondes NanoSIMS dont l'acquisition d'image sera possible par les halogènes présents dans la structure et les sondes bimodales comportant les deux éléments dans la même structure. Les sondes bimodales sont obtenues par le couplage pallado-catalysé de Sonogashira. Dans la dernière partie du chapitre, une nouvelle série de sonde a été envisagée dans le cadre d'une application future : le marquage de l'ATP-ϒ-SH grâce à une fonction mésylate. Les deux derniers chapitres ont pour but de mettre en application tout ce qui a été présenté dans les chapitres précédents. Les deux techniques employées permettent d'accéder à des types d'informations différentes : la spectroscopie Raman donne accès aux modes de vibrations d'une molécule tandis que l'imagerie NanoSIMS permet d'obtenir des informations élémentaires et isotopiques. Nous présenterons le cheminement suivi pour imager des cellules via leurs constituants par micro-spectroscopie Raman et imagerie NanoSIMS via les sondes moléculaires introduites. / Life sciences imaging are widely used for different applications, they are interested in medical diagnosis as well as basic research. In cells biology, fluorescence microscopy is mainly used for organelles observation at sub-cellular scale. However, techniques based on fluorescence phenomena are limited by some drawbacks like technical resolution, fluorescent dye degradation and the number of channels, which can be visualized. In this context, the exploration and the development of new way for image acquisition are considered as an experimental and technical scientific challenge. Furthermore, it can lead to complementary technique to fluorescence microscopy.This PhD thesis is a life science imaging project development and application allowing image acquisition base on molecular vibrations phenomena and elementary analysis in cells. Two techniques have been chosen in relation to both specificity: micro Raman spectroscopy and NanoSIMS imaging. Micro Raman spectroscopy allows the observation of molecular vibration mode at micron scale and NanoSIMS leads to elementary and isotopic sample information at sub-micronic scale. Combination of both techniques will lead to multi-scale and multi-modal imaging of biological samples. Molecular probes designing and synthesis for both techniques were used to visualize an organelle inside the nucleus: the nucleolus. Nucleolus has a key role in ribosomal RNA transcription and researchers shows some interest in the study of this organelle for his multifunctional role like ribosome biogenesis and nuclear organization. An immuno-labelling method combine with the introduction of molecular probes will allow nucleolus imaging by micro-Raman spectroscopy and NanoSIMS spectrometry. This immuno-labelling is specific to a phosphoprotein mainly localized inside the nucleolus: the nucleophosmin (NPM). In this project, the introduction of molecular probes in an immuno-labelling will act as a Raman Tag or a NanoSIMS tag for NPM's nucleolus observation and studies.This work at the interface between different fields: chemistry, biology and physics shows all the aspect of this project starting from molecular probes synthesis, immuno-labelling methods uses to direct application of both Raman and NanoSIMS techniques.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-01-22T11:04:31Z No. of bitstreams: 1 wesleytinocoesteves.pdf: 1817304 bytes, checksum: 6ff6e2f42ca29b6d9a247cd5c28895ef (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-01-25T18:50:19Z (GMT) No. of bitstreams: 1 wesleytinocoesteves.pdf: 1817304 bytes, checksum: 6ff6e2f42ca29b6d9a247cd5c28895ef (MD5) / Made available in DSpace on 2016-01-25T18:50:19Z (GMT). No. of bitstreams: 1 wesleytinocoesteves.pdf: 1817304 bytes, checksum: 6ff6e2f42ca29b6d9a247cd5c28895ef (MD5) Previous issue date: 2014-12-02 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O presente trabalho buscou estabelecer um método para a determinação de contaminantes inorgânicos em leite cru que fosse compatível com aplicações em larga escala, como os programas regulatórios de monitoramento de contaminantes em leite. Para tal, foi proposta uma abordagem utilizando a técnica de espectrometria de emissão atômica em plasma (ICP-AES) sem mineralização das amostras, que foram solubilizadas em solução contendo etanolamina e ácido cítrico. Estudos foram conduzidos a fim de estabelecer condições instrumentais em que fosse possível utilizar o preparo amostral proposto mantendo o compromisso com a sensibilidade, exatidão e desempenho analítico necessários a fim de se atingir os limites de detecção requeridos por legislações relacionadas à segurança alimentar. A proporção ideal de diluição da amostra na solução de etanolamina e ácido cítrico foi de 1:2 (amostra:solução) e os valores mais adequados dos parâmetros instrumentais foram 1300W para a radiofrequência do plasma, 0,50L.min-1 para a vazão do gás auxiliar e 0,60L.min-1 para a vazão do gás de nebulização. Os limites de quantificação obtidos para Cd, Co, Cr, Cu e Pb foram, respectivamente, 6,54, 6,57, 14,8, 14,3 e 27,4 μg.mL-1. / This study aimed to establish a method for the determination of inorganic contaminants in raw milk that was compatible with largescale applications, such as regulatory programs for the monitoring of contaminants in milk. For this purpose, an approach using the technique of atomic emission spectrometry (ICP-AES) with no mineralization of the samples, which was solubilized in a solution containing ethanolamine and citric acid, has been proposed. Studies were conducted in order to establish experimental conditions in which it was possible to use the proposed sample preparation and keeping the commitment to sensitivity, accuracy and the analytical performance required by legislations related to food safety. The ideal ratio of sample dilution was 1:2 (sample:solution) and the most suitable values for instrumental parameters were 1300W for the plasma radiofrequency power, 0.50L.min-1 for the flow of auxiliary gas and 0.60L.min-1 for the flow of nebulizer gas. The quantification limits obtained for Cd, Co, Cr, Cu and Pb were, respectively, 6.54, 6.57, 14.8, 14.3 and 27.4 μg.mL-1.

Diplomová práce popisuje fyzikální principy mikroskopů TEM, SEM a STEM spolu s jejich vhodností pro pozorování vzorků citlivých na elektrony, jako jsou zalévací média či biologické vzorky. Dále je popsána příprava vzorků pro STEM (TEM) a popis interakcí, ke kterým dochází mezi primárním elektronovým svazkem a vzorkem. Součástí práce je také pojednání o zpracování mikroskopických obrazů s podkapitolou o metodách kvantitativního porovnání obrazů ze STEM. Praktická část práce je zaměřena zejména na měření úbytku hmoty zalévacích médií (Epon, Spurr, LR White) způsobený primárním svazkem elektronů v nízkonapěťovém STEM. Ultratenké řezy několika tlouštěk byly zkoumány při různých nastaveních mikroskopu (urychlovací napětí, celková dávka, proud svazku, čištění povrchu vzorku a komory mikroskopu) a zobrazovacích módech (světlé a tmavé pole). Dále jsou zkoumány také biologické vzorky Krásnoočka štíhlého (Euglena gracilis) zalitého v pryskyřicích Epon a Spurr. Nasbírané snímky, vytvořené algoritmy a získané výsledky jsou diskutovány a zhodnoceny.

This master’s thesis deals with the possibility of manufacturing gas analyzer by Rapid Prototyping Technology and it with the method Direct Metal Laser Sintering. The theoretical part describes the current production of component in the Frentech Aerospace LLC and innovation with the DMSL method in the company Innomia Furthermore JSC. Then an analysis of the principle of single methods Rapid Prototyping, especially the method of Direct Metal Laser Sintering, is implemented. The aim of the experimental part is to compare the mechanical properties and material structures, conventional metallurgy and powder metallurgy. The thesis also contains a technical-economic evaluation comparing the manufacture of mechanical part by conventional and advanced additive technology.

With the introduction of nanoparticles in health care and daily products, the interaction between cells and nanoparticles is of great interest. There are many ways to examine these interactions, one of them being soft X-ray microscopy. It is a technique utilizing the water window to image biological samples, its greatest benefit being the non-invasive sample preparation, keeping the cell in a near-native state. The Stockholm Laboratory Soft X-ray Microscopy is a compact soft X-ray microscope that is currently being used to examine cell interactions. However, the sample preparations have been inconsistent and have yielded few useful and reproducible results. The purpose of this project is to optimize the cell preparation for better imaging using the Stockholm Laboratory Soft X-ray Microscope.  To reach the project goal to enable imaging of the nucleus and organelles in macrophages, this thesis will present a sample preparation protocol for macrophages where the concentration, blotting and cryo-fixation of the samples have been improved. The macrophage preparation was also tried on two other types of cells, amoeba and HEK 293 cells, to see if this preparation is universal for all cell lines. The results indicated that the most difficult and crucial step is the blotting, as too dry samples destroy the cells and too wet samples will yield almost no transmission in the microscope, making it impossible to image. / Med introduktionen av nanopartiklar i vården och dagliga produkter är samspelet mellan celler och nanopartiklar av stort intresse. Det finns många sätt att undersöka dessa interaktioner, ett av dem är mjuk röntgenmikroskopi. Det är en teknik som använder vattenfönstret för att avbilda biologiska prover, vars största fördel är den icke-invasiva provberedningen, som håller cellen i ett nästan naturligt tillstånd. Stockholm laborativa mjukröntgenmikroskop är ett kompakt mjuktröntgenmikroskop som för närvarande används för att undersöka cellinteraktioner. Provberedningarna har dock varit inkonsekventa och har gett få användbara och reproducerbara resultat. Syftet med detta projekt är att optimera cellförberedelsen för bättre avbildning med hjälp av Stockholm laborativa mjukröntgenmikroskop. För att uppnå projektmålet att möjliggöra avbildning av cellkärnor och organeller i makrofager, så kommer denna avhandling att presentera ett provberedningsprotokoll för makrofager där koncentrationen, blotting och kryofixering av proverna har förbättrats. Makrofag-preparatet testades även på två andra typer av celler, amobea- och HEK 293-celler, för att se om detta preparat är universellt för alla cellinjer. Resultaten visade att det svåraste och mest avgörande steget är blotting, eftersom för torra prover förstör cellerna och för våta prover kommer att ge nästan ingen överföring i mikroskopet, vilket gör det omöjligt att avbilda.

Sample preparation is the most critical step in proteomics as it directly affects the subset of proteins and peptides that can be reliably identified and quantified. Although a variety of efficient and reproducible sample preparation strategies have been developed, their applicability and efficacy depends much on the biological sample. Here, three approaches were evaluated for the human milk and plasma proteomes. Protein extracts were digested either in an ultrafiltration unit (filter-aided sample preparation, FASP) or in-solution (ISD). ISD samples were desalted by solid-phase extraction prior to nRPC-ESI-MS/MS. Additionally, milk and plasma samples were directly digested by FASP without prior protein precipitation. Each strategy provided inherent advantages and disadvantages for milk and plasma. FASP appeared to be the most time efficient procedure with a low miscleavage rate when used for a biological sample aliquot, but quantitation was less reproducible. A prior protein precipitation step improved the quantitation by FASP due to significantly higher peak areas for plasma and a much better reproducibility for milk. Moreover, the miscleavage rate for milk, the identification rate for plasma, and the carbamidomethylation efficiency were improved. In contrast, ISD of both milk and plasma resulted in higher miscleavage rates and is therefore less suitable for targeted proteomics.

A influência das variáveis associadas ao laser como a fluência, o comprimento de onda, e a duração do pulso, assim como as relacionadas às propriedades das amostras, como a distribuição do tamanho das partículas e as características químicas da matriz, foram avaliadas visando à determinação quantitativa de macro- (P, K, Ca, Mg) e micronutrientes (Cu, Fe, Mn, Zn, B) em pastilhas de materiais vegetais por espectrometria de emissão óptica com plasma induzido por laser (LIBS). Os efeitos da distribuição do tamanho das partículas e da fluência do laser foram investigados a partir da análise de amostras peneiradas (150-20 µm) empregando-se um sistema LIBS, em regime temporal de nanossegundos (ns-LIBS), montado com um laser de Nd:YAG a 1064 nm (pulsos de 5 ns e 360 mJ)e um espectrômetro com óptica Echelle e detector ICCD. Observou-se um aumento na sensibilidade e na precisão das medições com a diminuição do tamanho das partículas usadas no preparo das pastilhas, e uma diminuição dos efeitos de matriz causados por diferenças no tamanho das partículas, quando pastilhas preparadas com partículas < 75 µm foram analisadas com pulsos de 50 J cm-2. Verificou-se uma melhora significativa na exatidão das medições de Mg, Fe, Mn e Zn feitas em um conjunto de pastilhas de folhas de cana-de-açúcar (partículas < 75 µm) empregando-se esta fluência. Em uma segunda etapa, observou-se que variações no comprimento de onda do laser de Nd:YAG (1064, 532, 355 e 266 nm) não influenciaram de maneira significativa a precisão e exatidão das medições em pastilhas de folhas de cana-de-açúcar, obtendo-se correlações lineares entre as intensidades dos sinais de emissão e as correspondentes frações de massa dos analitos. Variações no comprimento de onda do laser de Nd:YAG não afetaram a análise de um conjunto heterogêneo de amostras, composto por pastilhas de folhas de plantas de diferentes espécies, como soja, cana-de-açúcar, milho, citros, café, por exemplo, por ns-LIBS. No entanto, diferentemente do observado para o conjunto de pastilhas de folhas de cana-de-açúcar, observou-se, uma baixa correlação (r cal < 0,90) entre as frações de massa de Ca, Mg, P, Cu, Fe, Mn e Zn determinadas por ns-LIBS e os valores de referência, o que demonstra a baixa robustez de ns-LIBS frente às variações na composição química das matrizes. Posteriormente, analisou-se este conjunto heterogêneo de amostras com sistema LIBS, em regime temporal de femtossegundos (fs-LIBS), montado com laser de Ti:Safira (pulsos de 60 fs e 1,65 mJ) e espectrômetro com óptica Czerny-Turner e ICCD. Demonstrou-se que o uso de pulsos em regime de fs proporcionou calibrações e validação menos dependentes da composição química das matrizes. As frações de massa de Ca, Mg, P, Fe e Mn previstas por fs-LIBS foram estatisticamente concordantes com os valores de referência, independentemente do modelo de calibração usado. Além disso, o uso de calibração multivariada melhorou a capacidade preditiva de ns-LIBS, assemelhando-se à de fs-LIBS. Concluiu-se que o emprego de fs-LIBS foi a estratégia mais robusta e que ofereceu maior flexibilidade à variabilidade matricial / The influence of laser properties, such as fluence, wavelength and pulse duration, as well as sample characteristics, such as particle size distribution and chemical matrix composition, was evaluated aiming at the quantitative determination of macro- (P, K, Ca, Mg) and micronutrients (Cu, Fe, Mn, Zn, B) in pellets of plant materials by laser-induced breakdown spectroscopy (LIBS). Firstly, the effects of particle size distribution and laser fluence on the analysis of pellets (test samples) prepared with sieved samples (from 150 to 20 µm apertures) were investigated. Experiments were carried out with a nanosecond LIBS (ns-LIBS) system by using a Q-switched Nd:YAG laser at 1064 nm (5 ns; 360 mJ) and a spectrometer with Echelle optics and intensified charge-coupled device (ICCD) detector. Results indicated that smaller particles yielded to sensitivities\' enhancement and attained better measurements\' precision. Moreover, matrix effects were reduced by analyzing pellets prepared from < 75 ?m sieved fractions and pulses of 50 J cm-2. In addition, there was a significant improvement on accuracy of Mg, Fe, Mn and Zn measurements in a set of test samples of sugarcane leaves by using this fluence. In a second experiment, variations in the Nd:YAG laser wavelength (1064, 532, 355 and 266 nm) did not affect the analysis of test samples of sugarcane leaves, and provided linear correlations between emission signal intensities and corresponding analytes mass fractions. In addition, variations within Nd:YAG laser wavelength did not affect the analysis of a heterogeneous sample set composed by pellets of leaves from different crops, such as soy, sugarcane, maize, citrus and coffee by ns-LIBS. However, in contrast to previous findings, the univariate calibration models for ns-LIBS presented lower linearity (r cal < 0.90) for Ca, Mg, P, Cu, Fe, Mn and Zn, no matter the laser wavelength used for the analysis. These circumstances reflect the low robustness of ns-LIBS to variations within matrix chemical composition among test samples. Afterwards, test samples from different crops were analyzed by a femtosecond LIBS (fs-LIBS) by using a Ti:Sapphire laser, including a mode-locked oscillator and an ultrafast amplifier (60 fs; 1.65 mJ per pulse), and a spectrometer with Czerny-Turner optics and ICCD. Findings indicated that the pulse duration was a decisive variable for providing accurate quantification of nutrients in different plant species, which present substantial differences in terms of matrix chemical composition. Close agreement between Ca, Mg, P, Fe and Mn mass fractions predicted by fs-LIBS and those determined by ICP OES was evidenced, whatever the modeling approach used. Contrarily, for ns-LIBS analysis of test samples from different crops, only the use of multivariate partial least squares (PLS) regression appears capable for resolving the non-linear transformations of the emission intensities according to the physical mechanisms governing this temporal regime of ablation. Thus, when using multivariate modeling, the figures-of merit reflecting the predictive capabilities of ns-LIBS resemble to those achieved by fs-LIBS. Either way, fs-LIBS is a more robust approach that better offers larger flexibility to the matrix variability

A cominuição de amostras geológicas envolve etapas para reduzir seus grãos garantindo sua representatividade, com o auxílio de vários equipamentos de moagem de amostras. São duas as contaminações que podem ser causadas durante o uso desses equipamentos. A primeira é a contaminação primária, pelo contato face a face entre a amostra e os componentes do sistema de moagem, e a segunda é a contaminação cruzada, derivada do material de outras amostras, previamente tratadas, que esteja depositado na superfície dos equipamentos de moagem. São limitadas as informações encontradas na literatura acerca das contaminações primárias, a maioria dos autores presumindo que a mesma seja maior na etapa final dos processos de tratamento. Ainda assim, se faz necessário um estudo sistemático sobre as possibilidades de contaminação primária, durante as diversas etapas de tratamento das amostras. Para esta pesquisa foram utilizadas amostras de quartzo puro, coletado na Fazenda Batatal, em Diamantina, Minas Gerais, com o exame da contaminação primária causada pelo uso dos equipamentos de fragmentação (britador de mandíbulas primário de aço manganês, britador de mandíbulas secundário de carbeto de tungstênio e prensa hidráulica com acessórios de fragmentação em aço) e, a seguir, os de pulverização (moinho de anéis de ágata, carbeto de tungstênio e aço-Cr). O quartzo, um dos materiais mais puros encontrados na natureza, é o que apresenta dureza suficientemente alta para promover intensos processos de interação e contaminação mais extrema. Posteriormente, avaliou-se a possibilidade da contaminação cruzada em quartzo causada pelo tratamento prévio de amostras de basalto (o RS132, da Formação Serra Geral, Rio Grande do Sul) e de granito (o ITU-06.04A, da intrusão Salto, Salto, São Paulo), utilizadas como padrões nos laboratórios do Instituto de Geociências da Universidade de São Paulo, IGc-USP, com composições determinadas por fluorescência de raios X (FRX), no Laboratório de FRX do IGc-USP. As determinações químicas em soluções convenientemente preparadas de amostras de quartzo, utilizadas nas etapas de contaminação primária e cruzada, foram realizadas por espectrometria óptica com plasma indutivo acoplado (ICP-OES) e espectrometria de massa com plasma indutivo acoplado (ICP-MS) no Laboratório de Química e ICP-OES/MS do IGc-USP. Para estudos da contaminação primária foram geradas alíquotas Q1A, Q1B, Q1C, Q2A, Q2B, Q2C, Q3A, Q3B e Q3C (1 identifica tratamento por britador primário de ferro fundido, 2 o britador secundário de CW, 3 a prensa de aço-carbono; e A, B e C identificam os moinhos de anéis na moagem final: ágata, CW e aço-cromo). Nos estudos da contaminação cruzada foram geradas quatro alíquotas, Q4A-Gcc e Q4B-Gcc (quartzo pulverizado, respectivamente, em moinho de anéis de ágata e de CW, após pulverização do granito), e Q4A-Bcc e Q4B-Bcc (quartzo pulverizado nos mesmos moinhos, após tratamento do basalto). A única contaminação registrada foi causada pelos equipamentos durante cominuição primária do quartzo. A ambientação dos moinhos realizada após a moagem de granito ou basalto foi efetuada mediante limpeza rotineira, seguida de moagem com areia quartzosa (a seguir descartada), procedimento efetivo para evitar contaminação cruzada, por remover o material (basáltico ou granítico) aderido às superfícies dos equipamentos. O britador primário de aço manganês colabora com contaminações por Fe e Mn e elementos Cr, Mo, Cu, Sc e Nb, em teores menores. O britador de mandíbulas secundário de CW contaminou com W, provavelmente também com C (determinado por programa Total-Quant), e com algo de Al. A prensa em aço carbono contamina em níveis de 50 ppm de Fe, e teores menores de Cr e Mn. Moinhos pulverizadores de aço temperado contaminaram principalmente com Fe e Cr e, em teores menores, com Mn, W, Ni, Zn, Mo, e V. Cu e Sc aparecem também em níveis extremamente baixos nas amostras tratadas, e podem ser adicionados por estes moinhos. O moinho de anéis de CW contaminou com W (1000 ppm) e Co (70 ppm), aparecendo ainda C com teores apreciáveis; também contamina com Ta e Nb (em torno de 2 e 0,6 ppm, respectivamente). As determinações de vários elementos-traço no quartzo pulverizado em moinho de anéis de ágata ficaram muito próximas, ou abaixo, do limite de detecção das técnicas utilizadas, não se documentando nenhuma contaminação por efeito da utilização deste equipamento. / The grinding of geologic samples is performed to reduce grain size of the constituting minerals and to preserve a representative sample of the original material, with the help of several grinding and milling equipments. The primary and a secondary or crossed contamination are the possible effects that can be produced during these processes. The first is caused by the interaction between the components of the grinding equipments and the sample, the second derives from contamination by other geologic materials previously ground in those equipments. The information found in the previous literature on the subject is relatively limited, most authors assuming that the main contamination may be produced during the final stages of comminution, the one leading to the generation of fine powders. Thus, there is a need to conduct a systematic survey about extent and possibility of primary contaminations. The materials used are samples of pure quartz crystals from the Fazenda Batatal, city of Diamantina, Minas Gerais state, with research initially centered on the examination of primary contamination caused by the fragmentation equipment (manganese steel primary crusher, W carbide secondary crusher, hydraulic press with steel anvil) and then grinding to fine powder (ring grinders equipped with agate, W carbide or chrome-steel rings). Quartz, one of the purest substances found in nature, is a hard mineral that interacts vigorously with the grinding equipment, therefore causing more extreme contamination. A second round was performed testing crossed contamination in quartz caused by previous grinding of basalt (RS 132, Serra Geral Formation, Rio Grande do Sul state) and granite (ITU-06.04A, from the Salto intrusion, city of Salto, São Paulo state), used as standards at the chemistry laboratories of the Instituto de Geociências, Universidade de São Paulo (IGc-USP), with their compositions determined by XRF at Igc-USP. The other chemical determinations, performed on samples of quartz solutions, for checking primary as well as crossed contamination, were performed on ICP-OES and ICPMS equipments, at the Chemistry and ICP-OES/MS Laboratory of Igc-USP. For the testing of primary contamination, the quartz aliquots Q1A, Q1B, Q1C, Q2A, Q2B, Q2C, Q3A, Q3B, and Q3C were prepared (1, 2 and 3 identify, respectively, primary jaw crusher with iron jaws, the secondary crusher with W carbide jaws and the hydraulic press with carbon steel anvil; A, B and C stand for the three used ring grinders, respectively equipped with agate, W carbide and chrome steel rings). Crossed contamination was tested with the aliquots Q4A-Gcc and Q4B-Gcc (quartz samples powdered, respectively, in the agate ring grinder and the CW ring grinder, after grinding of granite), and Q4A-Bcc and Q4B-Bcc (the same procedures as before, now with previous grinding of basalt). The only contamination registered in this study was caused during primary crushing and grinding of the quartz samples. Cleansing of equipment performed after grinding of basalt or granite using conventional cleaning techniques followed by grinding of quartzose sand (later discarded), is a procedure that erases the previous (basaltic or granitic) material from the used equipment; no significant crossed contamination was registered. The primary manganese steel crusher adds principally Fe and Mn to quartz, and elements as Cr, Mo, Cu, Sc and Nb, in lesser amounts. The secondary W carbide jaw crusher contaminates with W, probably also with C (determined with the TotalQuant program), and also with some Al. The carbon steel press contributes with contamination of about 50 ppm Fe, and lesser amounts of Cr and Mn. Powdering mills with tempered steel add mainly Fe and Cr and, to lesser extents, also Mn, W, Ni, Zn, Mo, and V to the quartz; Cu and Sc are present as possible contaminants in very low levels. The W carbide ring mill contaminates quartz with W (around 1000 ppm) and Co (around 70 ppm), adding significant levels of C. This mill contributes also with Ta and Nb additions (2 and 0.6 ppm, respectively). The determination of trace elements in quartz powdered with the agate ring mills does not register significant increases in the analyzed amounts, with levels that remain close to, or below, the respective detection limits, thus possibly precluding any contamination with the use of these mills.