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Determination of Ca and P in foods and B, Si, P and S in steels by dynamic reaction cell inductively coupled plasma mass spectrometry

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Ultrasonic slurry sampling electrothermal vaporization dynamic reaction cellTM inductively coupled plasma mass spectrometry (USS-ETV-DRC-ICP-MS) has been applied to the determination of As and Se in soil and sediment samples. The influences of instrument operating conditions and slurry preparation on the ion signals were reported. Ascorbic acid and Pd were used as the modifiers to enhance the ion signals. The background ions at the selenium masses were reduced in intensity significantly by using 1.5 ml min-1 H2 as reaction cell gas in the DRC while a q value of 0.65 was used. Since the sensitivities of As and Se in slurry solution and aqueous solution were quite different, standard addition method was used for the determination of As and Se in these samples. This method has been applied to the determination of As and Se in NIST SRM 2711 Montana soil and SRM 2709 San Joaquin soil reference materials and NRCC BCSS-1 marine sediment reference sample. The analysis results of the reference materials were agreed with the certified values. The method detection limits estimated from standard addition curves were about 0.046-0.082 and 0.019-0.024 mg g-1 for As and Se, respectively, in original soil and sediment samples.

No description available.

No description available.

L’ADN est reconnu depuis longtemps comme une des molécules fondamentales des organismes vivants.Support de l’information génétique, la molécule d’ADN possède aussi des propriétés qui en font unmatériel de choix pour construire à l’échelle nanométrique. Deux simples brins d’ADN complémentaireset antiparallèles (c.à.d. de directivité opposée) peuvent, par exemple, s’hybrider s’ils se rencontrent ensolution, c’est à dire s’associer l’un à l’autre. La cohésion de la molécule « double-brin » ainsi forméeest maintenue par une série de liaisons faibles entre les bases complémentaires de chaque brin. Cetteréaction d’hybridation de l’ADN est réversible : un double-brin stable à basse température retrouveral’état simple-brin à plus haute température.Notre capacité à lire (séquencer) et écrire (synthétiser) l’ADN est à l’origine de l’émergence dudomaine des nanotechnologies ADN. Cette capacité à prévoir quantitativement les interactions (cinétiqueset thermodynamiques) entre deux partenaires moléculaires quels qu’ils soient est propre à l’ADN: on peut facilement synthétiser deux molécules de même taille et nature, de manière à ce qu’elles interagissent– ou non – selon la séquence qui leur est propre. Il existe aussi toute une batterie d’enzymescapables de catalyser différentes réactions au sein d’un brin d’ADN ou entre deux brins d’ADN, parexemple : une polymérase catalyse la synthèse d’un brin d’ADN à partir de son complémentaire ; unenickase coupe un seul des deux brins d’une molécule double-brin à un emplacement spécifique ; uneexonucléase hydrolyse un brin d’ADN en fragments plus courts, tandis qu’une ligase lie deux brinscourts en un brin unique, plus long. Dans cette thèse, nous commençons par vérifier que les trois modules de l’oligator (activation,autocatalyse et inhibition) peuvent être réarrangés de manière arbitraire, afin de créer différents circuitsde réactions dynamiques. Nous appellerons cette collection de réactions catalysées par trois enzymes(polymérase, nickase et exonucléase) la boite à outils ADN. La construction et le contrôle de circuitscomplexes nécessitent de pouvoir observer les modules désirés de manière spécifique et en temps réel.A cette fin, nous mettons au point une nouvelle technique de fluorescence utilisant une interaction– souvent négligée – entre les bases d’ADN et un fluorophore qui y est attaché : celui-ci émet unefluorescence dont l’intensité dépend de l’état (simple ou double brin) et de la séquence à proximité dufluorophore. / Biological organisms process information through the use of complex reaction networks. These can bea great source of inspiration for the tailoring of dynamic chemical systems. Using basic DNA biochemistry–the DNA-toolbox– modeled after the cell regulatory processes, we explore the construction ofspatio-temporal dynamics from the bottom-up.First, we design a monitoring technique of DNA hybridization by harnessing a usually neglectedinteraction between the nucleobases and an attached fluorophore. This fluorescence technique –calledN-quenching– proves to be an essential tool to monitor and troubleshoot our dynamic reaction circuits.We then go on a journey to the roots of the DNA-toolbox, aiming at defining the best design rulesat the sequence level. With this experience behind us, we tackle the construction of reaction circuitsdisplaying bistability. We link the bistable behavior to a topology of circuit, which asks for specificDNA sequence parameters. This leads to a robust bistable circuit that we further use to explore themodularity of the DNA-toolbox. By wiring additional modules to the bistable function, we make twolarger circuits that can be flipped between states: a two-input switchable memory, and a single-inputpush-push memory. Because all the chemical parameters of the DNA-toolbox are easily accessible,these circuits can be very well described by quantitative mathematical modeling. By iterating thismodular approach, it should be possible to construct even larger, more complex reaction circuits: eachsuccess along this line will prove our good understanding of the underlying design rules, and eachfailure may hide some still unknown rules to unveil.Finally, we propose a simple method to bring DNA-toolbox made reaction circuits from zerodimensional,well-mixed conditions, to a two-dimensional environment allowing both reaction anddiffusion. We run an oscillating reaction circuit in two-dimensions and, by locally perturbing it, areable to provoke the emergence of traveling and spiral waves. This opens up the way to the building ofcomplex, tailor-made spatiotemporal patterns.

Os minerais são de extrema importância no metabolismo geral e no desempenho produtivo e reprodutivo dos bovinos. Atualmente, no Brasil, existem poucos estudos sobre o diagnóstico de deficiências minerais em bovinos, através de análise de macroelementos e elementos traço em fluidos biológicos. A maior parte das informações disponíveis limitam-se ao diagnóstico clínico de deficiências isoladas e à análise de elementos nas pastagens e no solo, que podem sugerir deficiências sub clínicas de alguns minerais, mas apresentam várias limitações e interferências. O objetivo deste trabalho foi desenvolver um método de análise simples, com introdução direta da amostra, utilizando a técnica de q-ICP-MS e DRC-ICP-MS, para determinação de Ca, Cu, Fe, Mg, Zn, I, Mo, As, Se, Ni, Co, Ba, Cs, Mn e Pb em sêmen bovino. Para realização das análises, foi utilizada calibração em meio aquoso e as amostras foram diluídas na proporção 1:50 em solução contendo 0,01% v/v Triton® X-100 e 0,5% v/v de ácido nítrico. Também foram avaliadas a calibração por ajuste de matriz e a análise das amostras após digestão por microondas, para confirmação dos resultados obtidos por introdução direta e calibração em meio aquoso. O DRC foi essencial para determinação de níquel. O gás de reação utilizado foi H2 e os parâmetros RPq e vazão do gás foram estudados para otimização do método. Os limites de detecção para determinação de 44Ca, 63Cu, 57Fe, 24Mg, 64Zn, 127I, 98Mo, 75As, 82Se, 59Co, 138Ba, 133Cs, 55Mn e 208Pb foram: 0,262; 0,003; 0,168; 0,004; 0,004; 0,026; 0,007; 0,007; 0,033; 0,002; 0,005; 0,002; 0,003; 0,002 µg L-1 respectivamente, e para determinação de 60Ni por DRC-ICP-MS o LD foi 0,020 µgL-1. O método desenvolvido foi aplicado para determinação de 15 elementos em amostras de sêmen de bovinos de diferentes raças usadas em programas de reprodução e inseminação artificial. / The minerals are of extreme importance in the general metabolism and in the productive and reproductive performance of the bovines. Nowadays, in Brazil, few studies exist on the diagnosis of mineral deficiencies in bovine, through macroelementos analysis and trace elements in biological fluids. Most of the available information is limited to the clinical diagnosis of isolated deficiencies and the analysis of elements in the pastures and in the soil, that can suggest sub clinical deficiencies of some minerals, but present several limitations and interferences. The objective of this work was to develop a method of simple analysis, with direct introduction of the sample, using the technique of q-ICP-MS and DRC-ICP-MS, for determination of Ca, Cu, Fe, Mg, Zn, I, Mo, As, Se, Ni, Co, Ba, Cs, Mn and Pb in bovine semen. Aqueous medium calibration was used in the analysis and the samples were diluted in the proportion 1:50 in solution containing 0,01% v/v Triton® X-100 and 0,5% v/v of nitric acid. They were also evaluated the matrix matching and the analysis of samples after digestion for microwave, for confirmation of the results obtained by direct introduction and calibration in aqueous medium. DRC went essential for nickel determination. The reaction gas used it was H2 and the parameters RPq and gas flow rate were studied for optimization of the method. The detection limits for determination of 44Ca, 63Cu, 57Fe, 24Mg, 64Zn, 127I, 98Mo, 75As, 82Se, 59Co, 138Ba, 133Cs, 55Mn and 208Pb were: 0,262; 0,003; 0,168; 0,004; 0,004; 0,026; 0,007; 0,007; 0,033; 0,002; 0,005; 0,002; 0,003; 0,002 µg L-1 respectively, and for determination of 60Ni for DRC-ICP-MS the LOD was 0,020 µgL-1. The developed method was applied for determination of 15 elements in bovine semen samples of different breed used in reproduction programs and artificial insemination.

Biological organisms process information through the use of complex reaction networks. These can bea great source of inspiration for the tailoring of dynamic chemical systems. Using basic DNA biochemistry-the DNA-toolbox- modeled after the cell regulatory processes, we explore the construction ofspatio-temporal dynamics from the bottom-up.First, we design a monitoring technique of DNA hybridization by harnessing a usually neglectedinteraction between the nucleobases and an attached fluorophore. This fluorescence technique -calledN-quenching- proves to be an essential tool to monitor and troubleshoot our dynamic reaction circuits.We then go on a journey to the roots of the DNA-toolbox, aiming at defining the best design rulesat the sequence level. With this experience behind us, we tackle the construction of reaction circuitsdisplaying bistability. We link the bistable behavior to a topology of circuit, which asks for specificDNA sequence parameters. This leads to a robust bistable circuit that we further use to explore themodularity of the DNA-toolbox. By wiring additional modules to the bistable function, we make twolarger circuits that can be flipped between states: a two-input switchable memory, and a single-inputpush-push memory. Because all the chemical parameters of the DNA-toolbox are easily accessible,these circuits can be very well described by quantitative mathematical modeling. By iterating thismodular approach, it should be possible to construct even larger, more complex reaction circuits: eachsuccess along this line will prove our good understanding of the underlying design rules, and eachfailure may hide some still unknown rules to unveil.Finally, we propose a simple method to bring DNA-toolbox made reaction circuits from zerodimensional,well-mixed conditions, to a two-dimensional environment allowing both reaction anddiffusion. We run an oscillating reaction circuit in two-dimensions and, by locally perturbing it, areable to provoke the emergence of traveling and spiral waves. This opens up the way to the building ofcomplex, tailor-made spatiotemporal patterns.