Développement de méthodes d'évaluation de la teneur en éléments trace pour la qualité sanitaire des récoltes

Ce travail de recherche porte sur la mise en place d outils permettant d évaluer le transfert en éléments trace des sols agricoles vers les plantes. Il a été ciblé sur quatre éléments trace métalliques réglementés dans le sol et/ou la plante à savoir le cadmium, le cuivre, le plomb, le zinc, ainsi qu un élément trace supplémentaire en voie de réglementation, l arsenic. Dans un premier temps, un protocole d échantillonnage a été développé afin de disposer d un outil de diagnostic pré-récolte. Le cahier des charges a été défini de telle façon que ce protocole soit opérationnel, représentatif de la parcelle, applicable pour différentes parcelles et cultures et autorise une spatialisation de la concentration en éléments trace. Il est de type aléatoire stratifié afin de pouvoir couvrir la totalité de la surface étudiée. Dans un second temps, l étude s est portée sur le développement d une méthode d analyse des sols par électrochimie afin de disposer d un outil d évaluation de la biodisponibilité potentielle des éléments traces et donc du risque de transfert sol - plante. Pour ce faire, les concentrations des éléments sous leurs formes électrolabiles ont été déterminées par voltammétrie de redissolution anodique utilisant des électrodes sérigraphiées élaborées au laboratoire. La méthode a été développée et validée à partir d une solution de sol de référence minéralisé. Elle a été par la suite appliquée à des solutions de différents sols agricoles obtenues par lixiviation selon un protocole normalisé (NF ISO 18772).This study concerns the establishment of tools, which allow evaluating the transfer of trace elements from agricultural soils to plants. It focused on four metal trace elements regulated in soil and/or in plants, which are cadmium, copper, lead, zinc, as well as a trace element in the process of regulation, arsenic. First, a sampling protocol was developed in order to dispose of a tool of pre-harvest diagnostic. The specifications were defined such that this protocol is operational, representative of the parcel, applicable to various parcels and crops and authorizes a spatial distribution of the trace element concentration. It is based on random stratified type in order to be able to cover the whole of the considered area. Then, the study focused on the development of a soil analysis method by electrochemistry in order to dispose of a tool for assessing the potential bioavailability of trace elements and therefore the risk of the soil - plant transfer. For that, the electrolabile form concentrations of these elements were determined by anodic stripping voltammetry using screen printed electrodes produced at the laboratory. The method was developed and validated from a solution of a mineralized certified reference soil. It was subsequently applied to solutions of different agricultural soils obtained by leaching according to a normalized protocol (NF ISO 18772).PAU-BU Sciences (644452103) / SudocSudocFranceF

Nouveaux aspects de la réactivité chimique et électrochimique des clusters Pd3(dppm)3( 3-CO)n+ (n = 2, 1, 0)

Ce mémoire concerne l étude des clusters Pd3(dppm)3(CO)n+ (n = 2, 1, 0) (dppm = bis(diphénylphosphinométhane)) et sa réactivité chimique et électrochimique vis-à-vis de divers substrats. La première partie rappelle le contexte initial de formation du cluster, sa structure ainsi que ses propriétés, avec une mention particulière de sa réactivité envers les halogénures. La deuxième partie consiste en l exploitation des propriétés du cluster afin d activer des liaisons comprenant un halogène X, telles que les liaisons carbone-halogène C-X ou métal-halogène M-X de complexes organométalliques. L utilisation du cuivre comme alternative au palladium est également envisagée. La dernière partie décrit la réactivité du cluster vis-à-vis d autres espèces anioniques (H-, OH-), cationiques (H+) ou neutres (dérivés acétyléniques ou nitrosés) conduisant à la formation de nouvelles architectures moléculaires.This report deals with the study of Pd3(dppm)3(CO)n+ (n = 2, 1, 0) (dppm = bis(diphenylphosphinomethane)) clusters and its chemical and electrochemical behaviour towards various substrates. The first part deals with the initial context of cluster formation, its structure, properties and its reactivity towards halide ions. The second part reports the applications of the previously described cluster properties in order to activate bonds with a halogen atom X as the carbon-halogen bond C-X or the metal-halogen bond M-X of organometallic complexes. The use of copper instead of palladium is also considerated too. Finally, the last part describes the reactivity of cluster towards others anionic species (H-, OH-), cationic species (H+) or neutral species (ethynyl or nitroso substrates) which leads to novel molecular architectures.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

Corrosion or scale inhibitor dosage in industrial water

The present invention relates to a method for determining a concentration of a corrosion or scale inhibitor in a water sample comprising at least one corrosion or scale inhibitor, wherein said method comprises measuring the current as a function of the potential of one or more water samples thereby determining the concentration of said corrosion or scale inhibitor in said water sample. The present invention also relates to a method for determining the potential of a water sample comprising a corrosion or scale inhibitor, and a method for controlling or monitoring the concentration of one or more corrosion or scale inhibitors in an industrial fluid, and a kit for voltammetry analysis

Corrosion or scale inhibitor dosage in industrial water

The present invention relates to a method for determining a concentration of a corrosion or scale inhibitor in a water sample comprising at least one corrosion or scale inhibitor, wherein said method comprises measuring the current as a function of the potential of one or more water samples thereby determining the concentration of said corrosion or scale inhibitor in said water sample. The present invention also relates to a method for determining the potential of a water sample comprising a corrosion or scale inhibitor, and a method for controlling or monitoring the concentration of one or more corrosion or scale inhibitors in an industrial fluid, and a kit for voltammetry analysis

Erratum to “Elaboration of screen-printed microelectrodes working as generator/collector and their use in a flow cell system” [Sens. Actuators: B. Chem. 174C (2012) 225–230]

International audienceThe publisher regrets that the equations in section 3.3 (Performance of the dual-electrode in stationary mode) is incorrect as it had been mistakenly replaced with another equation during the production process. The correct equations for section 3.3 are as follows:Q + 2H+ + 2e− → QH2 generator electrode (cathode)QH2 → Q + 2H+ + 2e− collector electrode (anode)The publisher would like to apologise for the inconvenience caused

Elaboration of screen-printed microelectrodes working as generator/collector and their use in a flow cell system

International audienceA simple and cheap method has been developed to fabricate generator/collector microelectrodes. The elaboration of these electrodes consists in the deposit of consecutive layers of conductive ink and insulator by screen-printing. The two resulting working surfaces (microbands) are situated on the edge of the sensor and are separated by a very thin layer of insulator (17 μm). These microbands may be individually polarized at different potentials in order to generate a species at one of them and detect it at the other one. Cyclic voltammetry has been used to test and characterize the two working surfaces. The capacity of these dual-electrodes for working as generator/collector sensors is demonstrated by recording the generated and collected currents by chronoamperometry with a bipotentiostat. The collected current is about 30% of the generated current. These sensors have been adapted to a flow cell, allowing detection of sub-nanomoles of solute

Use of screen-printed microelectrodes working as generator/collector systems for the determination of the antioxidant capacity of phenolic compounds.

International audienceA new method using cheap homemade dual-electrodes has been developed to measure the antioxidant capacity of phenolic compounds. These micro-sized electrodes are elaborated by successive screen-printing of conductive ink and insulator layers and are then used as generator/collector sensors. Cyclic voltammetry and chronoamperometry with a bipotentiostat have been used to test and characterize these sensors. The antioxidant capacity values found by this new method are compared with a classical method (using a macro-sized electrode) to demonstrate its reliability

Speciation of copper in agricultural soils contaminated by lead using screen-printed electrodes and square-wave anodic stripping voltammetry (SPE-SWASV)

A SPE-SWASV method was developed, optimized and applied to determine total and electrolabile copper and lead concentrations in soil.</p

A new cyanoaromatic photosensitizer vs. 9,10-dicyanoanthracene: Systematic comparison of the photophysical properties

International audienceThe cyanoanthracene derivative, benzo[b]triphenylene-9,14-dicarbonitrile (1) can be prepared readily with a graftable function while maintaining 1O2 photosensitizing properties comparable to those of the standard compound 9,10-dicyanoanthracene (DCA). In view of the high potential of the derivatives of 1 for photooxidation reactions under heterogeneous conditions, we compared the photophysical properties of 1 in solution with those of DCA. In pursuing the comparison of 1 and DCA, we observed small but significant changes of the vibronic bands in the electronic absorption spectra of DCA in different solvents, which were well correlated with solvent polarity, similar to the pyrene polarity scale. The main difference between 1 and DCA is in the emission properties: we observed a much stronger sensitivity of the fluorescence emission spectrum to the electron-donating ability of the solvent than for DCA. The emission spectrum of 1 is in general structureless with a large Stokes shift. The ability of the singlet state of 1 to participate in charge transfer interactions with electron-donating solvents is proposed to account for these results. It makes 1 a highly sensitive probe to the surrounding medium. Reversible reduction was observed for both photosensitizers, with a small shift to more negative potentials for 1 compared to DCA. The reduction potential of the first singlet excited state is of the same order of magnitude in both cases. Several photo-oxidation reactions sensitized by 1 and DCA are compared in homogeneous solution and at the gas-solid interface by embedding 1 and DCA in silica monoliths. Our results confirmed the dual character of both cyanoanthracene derivatives as electron transfer and energy transfer sensitizers, highly efficient for singlet oxygen production