Induktiv gekoppelte Plasma-Massenspektrometrie mit Laserablation (LA-ICP-MS) wird zunehmend für die Einzelzellanalyse eingesetzt, jedoch wird eine weitere verbreitete Verbreitung durch den geringen Durchsatz behindert. Daher wurde in dieser Arbeit der Durchsatz von Einzelzellen-LA-ICP-MS untersucht und verbessert. Zunächst werden die beiden möglichen Ablationsmodi, Bildgebung und Einzelpunktanalyse (SSA), hinsichtlich ihrer analytischen Gütezahlen (Signal-Rausch-Verhältnis, Präzision, Genauigkeit, Durchsatz) verglichen. Hierfür wurden adhärente 3T3-Fibroblastenzellen mit zwei Metallfarbstoffen angefärbt und mit beiden Methoden mehrere Dutzend Zellen vermessen. SSA zeigte überlegene Eigenschaften hinsichtlich Durchsatz und Nachweisgrenzen. Darüber hinaus wurde gezeigt, dass >400 Zellen analysiert werden müssen, um zufriedenstellende Statistiken für einen quantitativen Vergleich der Ergebnisse zu erhalten, was als zu mühsam befunden wurde. Daher wurde ein Einzelzellen-Arraying-Schritt integriert, um eine automatisierte LA-ICP-MS-Analyse zu ermöglichen. Hierfür wurden zwei Arrayingverfahren getestet: Zunächst wurde das mikrofluidische Arraying von Zellen getestet, jedoch verhinderte das Einklemmen von weichen PDMS-Chips eine erfolgreiche Anwendung, und eine Neugestaltung des Chips wäre erforderlich. Daraufhin wurde eine neuartige Technologie getestet, die auf dem Arraying von Tröpfchen in Verbindung mit der Bilderkennung von Zellen beruht, wobei ein Anordnungsdurchsatz von 550 Zellen pro Stunde und eine beispiellose Einzelzellengenauigkeit (> 99%) gefunden wurde. In einem Proof-of-Principle-Experiment wurde ein Zellarray von THP-1-Suspensionszellen mittels LA-ICP-TOF-MS analysiert und erstmals gleichzeitig endogene und exogene Isotope einzelner Zellen als Isotopen-Fingerabdrücke von Zellen mit Nachweisgrenzen von lediglich wenigen hundert attogramm. Schließlich wurden diese Ergebnisse mit der derzeit gebräuchlichsten Analysemethode Single-Cell (sc)-ICP-MS verglichen. / Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is increasingly used for single-cell analysis. However, a more widespread use of LA-ICP-MS in single cell analysis is hampered by its low throughput. Hence, in this work the throughput of single cell LA-ICP-MS was studied and improved. First, the two possible ablation modes, imaging and single spot analysis (SSA) of single cells using a large laser spot, are compared regarding their analytical figures of merit (signal to noise, precision, accuracy, throughput), as well as regarding ease of operation and data evaluation. For that, adherent 3T3 fibroblast cells were stained with two metal dyes and several dozen cells were measured using both modes. SSA showed superior characteristics regarding throughput and detection limits. Moreover, it was shown that >400 cells must be analyzed to reach satisfactory statistics for a quantitative comparison of results, which would have been too laborious. Thus, a single cell arraying step was integrated to enable automated LA-ICP-MS analysis. Two different arraying methods were evaluated: First, arraying via hydrodynamic front trapping of cells using a microfluidic device was tested, but clamping of soft PDMS-chips prevented successful arraying and it was concluded that a major redesign of the chip is necessary. Secondly, and a novel technology relying on a microdroplet arrayer in conjunction with image recognition of cells was tested and a moderate arraying throughput (550 cells per hour) and an unprecedented single-cell accuracy (>99%) was found. In a proof of principle experiment, a cell array of THP-1 suspension cells was analyzed using LA-ICP-TOF-MS and endogenic and exogenic isotopes of individual cells were detected for the first time simultaneously as isotopic fingerprints of cells with detection limits as low as hundred attogram. Finally, these results were compared to the currently more commonly used analysis method single-cell (sc)-ICP-MS.

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Increased salinity in freshwater systems – also called the Freshwater Salinization Syndrome (FSS) – can have far-ranging implications for the natural and built environment, agriculture, and public health at large. Such risks are clearly on display in the Occoquan Reservoir – a drinking water source for roughly one million people in the northern Virginia/ National Capital Region. Sodium concentrations in the Occoquan Reservoir are approaching levels that can affect taste and health. The Reservoir is also noteworthy as a flagship example of indirect potable reuse, which further adds complexity to understanding the sources of rising levels of sodium and other types of salinity. To help understand the role residential discharges might play in salinization of the Occoquan Reservoir, a suite of laundry detergent products was identified based upon survey data collected in the northern Virginia region. The ionic compositions of these products were then characterized using ion chromatography and inductively coupled plasma-mass spectrometry to quantify select ionic and elemental analytes. Sodium, chloride, and sulfate were consistently found in appreciable amounts. To comparatively characterize the laundry detergents, principal component analysis was employed to identify clusters of similar products. The physical formulation of the products was identified as a marker for their content, with dry formulations (free-flowing and encapsulated powders) being more enriched in sodium and sulfate. This result was corroborated by comparing nonparametric bootstrap intervals for individual analytes. The study's findings suggest an opportunity wherein consumer choice can play a role in mediating residential salt inputs in receiving bodies such as the Occoquan Reservoir. / Master of Science / Many streams, rivers, and other freshwater systems have become increasingly salty in recent decades. A rise in salinity can be problematic, stressing aquatic life, corroding pipes, and even enhancing the release of more pollutants into the water. This phenomenon, called Freshwater Salinization Syndrome, can threaten such systems' ability to serve as sources of drinking water, as is the case for the Occoquan Reservoir in northern Virginia. Serving roughly one million people, the Reservoir is notable for being one of the first in the country to purposely incorporate highly treated wastewater upstream of a drinking water supply. Despite the Reservoir's prominence, the reasons behind its rising salt levels are not well understood. This study sought to understand the role that individual residences could play when household products travel down the drain and are ultimately discharged into the watershed. Laundry detergents are potentially high-salt products. A survey of northern Virginian's laundry habits was conducted to understand local tastes and preferences. Informed by the survey, a suite of laundry detergents was chemically characterized to measure salt and element concentrations. The detergents were found to have notable amounts of sodium, chloride, and sulfate in particular, with sodium being the most abundant analyte in every detergent. However, not all detergents were equally salty; statistical tools revealed that dry formulations (such as powdered and powder-filled pak detergents) contributed more sodium and sulfate, among other things. This study's findings suggest that laundry detergents could be contributing to Freshwater Salinization Syndrome in the Occoquan Reservoir, and that local consumers' choice of detergents could make a difference.

In dieser Arbeit wurde eine neue Markierungsstrategie von Antikörpern mit dem Markierungsreagenz MeCAT (Metal Coded Tag) unter physiologischen Reaktionsbedingungen, sowie deren Anwendung in einem 8-fach Multiplex-Immunoassay von in Formalin-fixierten und in Paraffin-eingebetteten Gewebeschnitten entwickelt. Für eine aussagekräftige LA-ICP-MS Detektion von MeCAT-modifizierten Antikörpern, wurde eine Standardisierung für biologische Proben auf NC-Membranen, basierend auf einer homogenen Aufbringung eines internen Standards und Kalibrierstandards durch einen kommerziell verfügbaren Tintenstrahldrucker entwickelt und mit der ICP-MS Analyse von Lösungen evaluiert. Die LA-ICP-MS wurde in zwei 8-fach Multiplex-Immunoassays von Tissue Micro Arrays vom Prostatakarzinom und in Maushirngewebeschnitten zur Einschätzung von neurogenerative Erkrankungen erfolgreich eingesetzt werden. Es konnte hierbei gezeigt werden, dass das Nachweisvermögen, der hier entwickelten Methode bereits ausreicht, um die gängigen klinischen Biomarker mit guter Ortsauflösung nachzuweisen. / In this work a new tagging strategy of antibodies with the tagging reagent MeCAT (Metal Coded Tag) was developed under physiological reaction conditions. Their application was proved in an 8-fold multiplex immunoassay of formalin-fixed and paraffin-embedded tissue sections. For a significant LA-ICP-MS detection of MeCAT tagged antibodies standardization for biological samples owere developed. The standardization based on a homogeneous deposition onto the NC membrane via conventional CD-ink-jet printer was validated in addition with the ICP-MS analysis of solutions. The internal standardization of LA-ICP-MS was successfully applied in two 8-fold multiplex immunoassays for Tissue Micro Arrays (TMA) of prostate cancer and for detection of biomarkers for neurodegenerative diseases in mouse brain tissue sections. In both examples it could be shown that the detection capability of the new tagging strategy in combination with the printing standardization allows the detection of the clinical biomarker with good spatial resolutions.

L'authenticité et la traçabilité des aliments gagnent un intérêt croissant au cours de la dernière décennie puisque la connaissance de la provenance des aliments est considérée comme une garantie supplémentaire de leur qualité. Les consommateurs ont également des inquiétudes et des préoccupations par l'origine de la nourriture qu'ils consomment car divers produits sont sujets à l'adultération ou à la fausse dénomination. L'intérêt accru à l’égard de la protection des consommateurs et de la lutte antifraude ont entraîné un accroissement de la recherche scientifique appliquée et le développement d'outils efficaces pour contrôler l'authenticité des produits alimentaires. Entre techniques analytiques appliquées à l'authenticité et à la traçabilité des aliments, les méthodes les plus prometteuses sont basées sur les empreintes d'éléments lourds mesurées par la spectroscopie atomique. La spectrométrie de masse à multicollection à couplage à plasma induit (MC-ICP-MS) est reconnue comme la méthode optimale pour effectuer des mesures de haute précision de nombreux éléments du tableau périodique en contrôlant simultanément les rapports entre leurs isotopes stables. Cette étude présente une nouvelle stratégie analytique basée sur des isotopes stables non-traditionnels combinés avec des éléments traces déterminés par ICP-MS. Les avantages de combiner les informations de deux systèmes isotopiques, l'un traçant le sol (Sr), et l'autre traçant la pollution environnementale ambiante (Pb), ont permis d'obtenir de nouvelles informations exceptionnelles sur la traçabilité et l'authenticité des matrices alimentaires sélectionnées : vins de Bordeaux, jambons secs et thé. En utilisant des techniques analytiques complémentaires telles que les empreintes des élémentaires traditionnelles, la spécification régionale, ainsi que le traçage du processus de préparation des aliments sont possibles. Traitée par la chimiométrie, cette approche analytique constitue un nouvel outil efficace et prometteur pour détecter des fraudes alimentaires, y compris l’imitation de produits de grande valeur, l’étiquetage erroné et la substitution par des produits moins cher. / Food authenticity and traceability have received an increasing interest during the last decade since the knowledge of food provenance is regarded as an additional warranty of its quality. The world's globalization brought to the consumers is more and more concerned with the origin of the food they eat because various products are subjected to adulteration or false denomination. The augmentative interest in anti-fraud and consumer protection has led to the extension of scientific research and development of effective tools of food authenticity control. Among the analytical technics applied to food authenticity and traceability, one of the most rapidly developing and promising method is based on fingerprinting of heavy elements detected by atomic spectroscopy. The multicollection inductively coupled plasma mass spectrometry (MC-ICP-MS) is recognized as a method of choice for the high precision measurement of numerous elements of the periodic table as well as ratios of their stable isotopes. This study present a new analytical strategy based on combined non-traditional stable isotopes and trace elements determination by ICP-MS. The benefits of combining information from two isotopic systems, one tracing the soil (Sr), and the other tracing environmental ambient pollution (Pb), allowed to obtain an exceptional new information about traceability and authenticity of selected food matrixes: prestigious Bordeaux wines, dry-cured hams and tea. Using complementary analytical techniques such as traditional elemental fingerprinting, the regional specification, as well as tracing of the food preparation process are possible. When combined with chemometrics, these analytical advances constitute an efficient and promising tool to detect food frauds, including adulteration of high value products with cheaper substitutes, forgery and falsification.

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).

Au cours de ces dernières décennies, des études ont étés menées pour identifier plusieurs traceurs des matériaux du cycle du combustible nucléaire, dans le cadre de la lutte contre la prolifération nucléaire. Ces matériaux sont généralement collectés lors d’inspections dans des installations nucléaires, ou saisis lors de contrôles de trafics illicites. Les informations fournies par ces traceurs sont parcellaires et ne permettent pas de déterminer avec exactitude la provenance et l’historique industriel de ces matériaux.Le but de ce travail de thèse est de démontrer le potentiel de l’utilisation des isotopes du molybdène pour le traçage des matériaux du cycle du combustible nucléaire. Le choix s’est porté sur le molybdène car en raison de la similarité de leurs propriétés chimiques, le molybdène et l’uranium sont étroitement associés dans les minerais d’uranium et tout au long de la chaîne de purification de l’uranium. L’étude s’est focalisée sur une partie de l’amont du cycle du combustible, depuis l’extraction des minerais d’uranium jusqu’à la production des concentrés miniers d’uranium : divers procédés physiques et chimiques sont appliqués, à la fois pour purifier l’uranium et abaisser la concentration en molybdène.Au cours de cette étude, une nouvelle méthode de séparation du molybdène a été développée pour caractériser sa composition isotopique dans des minerais, minéraux et concentrés miniers d’uranium. La variabilité des compositions isotopiques du molybdène dans un gisement d’uranium est principalement due aux mécanismes d’adsorption et/ou de précipitation du molybdène. Les gisements magmatiques et sédimentaires ont des compositions isotopiques différentes, ce qui permet ainsi leurs distinctions. Les concentrés miniers d’uranium produits à partir de ces deux types de gisements ont des compositions isotopiques similaires aux minerais. Ces résultats soulignent ainsi le potentiel des isotopes du molybdène comme traceur des origines des concentrés miniers d’uranium. Cependant, un fractionnement des isotopes du molybdène a été établi lors de la production des concentrés miniers d’uranium pour deux usines au Niger. Les procédés de purification de l’uranium tels que la lixiviation, l’extraction par solvant et la précipitation ont été reproduits en laboratoire sur des échantillons réels pour expliquer le fractionnement isotopique du molybdène lors de la production des concentrés miniers. Au cours de ces procédés, le fractionnement peut être positif (lixiviation), négatif (extraction par solvant, précipitation à l’eau oxygénée) ou nul (précipitation à l’ammoniaque). Dans le cas des échantillons du Niger, la somme de ces procédés est négative, dans le sens des données expérimentales que nous avons obtenues, démontrant ainsi également le potentiel de l’utilisation des isotopes du molybdène comme traceur des procédés de transformations des matériaux du cycle du combustible nucléaire. / Nuclear forensics aims at determining the age, provenance as well as industrial or storage history of uranium ores and uranium ore concentrates that are part of the nuclear fuel cycle. Several potential tracers have already been identified for this purpose. However, these tracers are not providing always unambiguous information. This study is focused on establishing Mo isotopes as a new tracer of uranium ore provenance and of ore processing for its application in nuclear forensics. Molybdenum and uranium share a number of common geochemical properties. In the nuclear fuel cycle, molybdenum is an impurity that is difficult to separate during uranium extraction and purification processes, while its concentration is required to be lower than some specification limits. We focused this study on the first part of the nuclear fuel cycle, from the uranium ores extraction to the production of uranium ore concentrates.We developed an enhanced separation method for Mo from a uranium-rich matrix (uranium ores, uranium minerals, uranium ore concentrates) in order to analyze the mass fractionation induced by processes typical of the nuclear fuel cycle. Molybdenum isotopic compositions in uranium ores depend of adsorption and precipitation processes. The δ98Mo values of sedimentary uranium ores is shifted to negative values relative to magmatic ores. This provides a means of distinguishing these types of uranium ores. Uranium ores concentrates produced from both uranium ore natures (magmatic and sedimentary) have Mo isotope compositions similar to the uranium ores. These results suggest that molybdenum isotopes have a strong potential of as a tracer for identifying the origin of the uranium ore concentrates. However, Mo isotopes fractionations were established during the production of uranium ore concentrates in the both Niger mills. We reproduced in laboratory the lixiviation, solvent extraction and precipitation processes to explain these observations. The Mo isotopes fractionation is positive for the lixiviation process, negative for the solvent extraction and precipitation with hydrogen peroxide, and null for ammonia precipitation. In the case of the Niger samples, the sum of these processes is negative and agrees with our experimental data. Mo isotopes have a strong potential as a tracer for identifying the origin and transformation of uranium in the nuclear fuel cycle, in the framework of nuclear forensics.

La caractérisation juste et reproductible en isotopie et en concentration des radioéléments est l’une des thématiques essentielles des laboratoires d’analyse dans le domaine du nucléaire. Afin de minimiser les temps de manipulation en boite à gants des personnels et la production de déchets radioactifs liés à l’analyse de combustibles nucléaires, il est nécessaire de proposer des solutions efficaces et innovantes. Depuis quelques années, la miniaturisation des systèmes séparatifs constitue l’un des axes de développement majeurs de la chimie analytique et ces microsystèmes constituent certainement une des solutions pour répondre aux exigences de l’analyse nucléaire. Ce travail a pour objectif la conception d’une plateforme analytique miniaturisée et à usage unique, dédiée a la séparation des lanthanides, issus des combustibles usés, en amont de leur analyse par spectrométrie de masse. Destiné à remplacer une étape de séparation chromatographique au centre d’un processus analytique de trois étapes, le nouveau protocole basé sur l’isotachophorèse (ITP) doit satisfaire un cahier des charges précis. Les propriétés de complexation des lanthanides ont d’abord été exploitées afin d’obtenir avec un agent chélatant unique et rigoureusement sélectionné, l’acide 2-hydroxy-2-methylbutyrique (HMBA), la sélectivité intra période nécessaire à leur séparation complète par ITP. Basées sur des modèles théoriques existants, des études complémentaires, notamment des paramètres influençant la résolution, ont permis l’amélioration des performances globales du système ainsi que son dimensionnement. Pour réduire drastiquement le volume de déchets liquides secondaires (solutions de rinçage) et la manipulation de matériaux et de matériels radioactifs, le protocole a été implanté sur un microsystème polymérique jetable en COC, spécialement développé pour cette application. Ce microsystème a ensuite été couplé à un spectromètre de masse a multi collection et source à plasma à couplage inductif pour mesurer les rapports isotopiques / The accurate and reproducible characterization of radioactive solutions in isotope composition and concentration is an essential topic for analytical laboratories in the nuclear field. In order to reduce manipulation time in glove box and production of contaminated wastes, it is necessary to propose innovative and efficient solutions for these analyses. Since few years, microchips are a major field of development in analytical chemistry and those devices could provide a solution which fits the needs of nuclear industry. The aim of this work is to design a disposable analytical micro-device devoted to lanthanide separation from spent nuclear fuel before their analysis in mass spectrometry. Designed to be used in place of a separation process by liquid chromatography which is involved in a three step protocol, the new protocol based on isotachophoresis (ITP) keeps compatible with the other two steps. The complete separation of lanthanides by ITP was obtained by the use of only one chelating compound rigorously selected: the 2-hydroxy 2-methyl butyric acid (HMBA). The main parameters involved in solute resolution were defined from the theoretical models of ITP and experimental studies of the influence of these parameters allowed to optimize the geometry of the system and to improve its performances. To suppress cleaning of the system and, consequently, to strongly reduce both liquid waste volume and handling radioactive material, the ITP protocol was transferred in a polymeric (COC) disposable microchip especially developed for this purpose