Intérêt de la microfluidique pour l'analyse des radioéléments

National audienc

Improved chromatographic performances of glycidyl methacrylate anion-exchange monolith for fast nano-ion exchange chromatography

International audienceAn efficient and reproducible photopolymerized poly(glycidyl methacrylate-co-ethylene dimethacrylate) was synthesized in Teflon-coated fused-silica capillaries (100 mu m id) and functionalized by reaction of triethylamine with reactive epoxy groups. We report here the successful transfer of a standard polymerization mixture optimized for the thermally initiated synthesis of glycidyl-based monolith to photo-induced polymerization. The monolith obtained after optimization of the photo-initiation conditions was characterized in reverse-phase chromatography evaluating its suitability in terms of efficiency, retention and hydrodynamic permeability. Reproducibility of the photo-induced procedure was satisfactory with RSD below 6% for retention and efficiency and slightly higher for hydrodynamic permeability (12%). The functionalized generic support was then used in nano-ion-exchange chromatography. Efficiencies up to 75 000 plates/m, ion-exchange capacity of 8 nano-equivalents/cm of monolithic column, with a combination of a satisfactory hydrodynamic permeability allowed to perform fast separations of five inorganic anions in <3 min maintaining baseline resolution. The efficiency of the monolith was not retention-dependent, demonstrating its wide range of possible applications for highly retained anions

Apport des monolithes polyméthacrylate en nano-chromatographie d'échange d'ions

International audienc

Mesures d'échantillons issus du démantèlement de G1 par autoradiographie digitale (MAUD)

International audiencePour le suivi des chantiers en assainissement démantèlement, les appareils de caractérisation sur le terrain sont essentiels. De nombreuses caméras dédiées à la mesure de rayonnements gamma, sont déjà industrialisées ou bien existent à l'état de prototype. Par contre, les développements de caméras capables de détecter les rayonnements alpha ou bêta sont beaucoup plus rares. Dans le cadre d'un projet de recherche soutenu par un PIA Andra, un démonstrateur industriel appelé MAUD qui utilise des détecteurs SiPM (Silicon Photomultipliers) couplés à des scintillants organiques a été développé pour répondre à ce manque. Les travaux présentés dans cette étude montreront l'utilisation sur le terrain de l'appareil MAUD. Le réacteur G1, construit en 1955 sur le site de Marcoule est à l'arrêt depuis 1968. Afin de préparer son démantèlement, un programme d'investigations et de prélèvements des différentes parties du réacteur est en cours. Ainsi, 48 carottes graphites du cœur du réacteur ont été extraites. La détermination de l'activité des radioélements présents(majoritairement des émetteurs beta pur), est généralement réalisée de manière destructive dans les laboratoires d'analyse. Ces opérations sont couteuses et très chronophages. L'appareil MAUD a été installé dans une boite à gant afin d'analyser la cinquantaine de carottes en graphites ainsi que des échantillons métalliques prélevés sur le réacteur en quelques semaines. L'interprétation des données a permis de -Classer les échantillons en fonction de leur niveau radioactif, -Caractériser la répartition de la radioactivité sur les différentes faces de la carotte (coté canal, bloc et sur la tranche)-Vérifier la présence de contamination en surface. En effet, l'analyse des spectres a permis d'identifier de manière qualitative certains radionucléides présents uniquement dans les échantillons les plus contaminés. Cette première étude a permis d'orienter la sélection des échantillons les plus pertinents à être examinés de façon destructive en laboratoire de chimie analytique. Elle contribue à moindre coût à optimiser le programme analytique

Determination of gluconate in nuclear waste by high-performance liquid chromatography: comparison of pulsed amperometric detection and electrospray mass spectrometry detection

International audienceThe measurement of gluconate is required in the framework of nuclear waste management. Liquid chromatography coupled with amperometric detection proved to be insufficiently selective to quantify gluconate in radioactive effluents due to the complexity of the matrix. An analytical method based on a desalting step and quantification with liquid chromatography coupled to mass spectrometry was therefore developed. As gluconate may be present as several chelates, speciation simulation studies enabled to determine the prevailing chelate form depending on experimental conditions and thus to optimize sample preparation. The analytical method was successfully applied to real nuclear effluents, with a limit of quantification of 2.6 × 10−5 mol L−1

Synthesis and Characterization of Ammonium Functionalized Porous Poly(glycidyl methacrylate-co-ethylene dimethacrylate) Monoliths for Microscale Analysis and Its Application to DNA Purification

International audienceA systematic study of parameters affecting the nucleophilic addition of secondary and tertiary amines on reactive epoxy groups was conducted on porous polymer monoliths. Reaction of small amines like diethylamine (DEA) or triethylamine (TEA) on poly(glycidyl methacrylate-co-ethylene dimethacrylate) monoliths (poly(GMA-co-EDMA)) allows to prepare anion exchange media. This study aimed to determine optimal and suitable conditions to prepare anion-exchange porous monolith inside 100 tun internal diameter capillary. The reaction kinetic of amine nucleophilic addition on porous poly(GMA-co-EDMA) monoliths was followed by FTIR-ATR spectroscopy. The reactivity of such epoxy-functionalized porous polymers was first determined through a study in pure amine solutions. Thereafter, conditions of reactions (i.e., temperature and time of reaction, solvent composition, concentration of amine) with respect to its further implementation at nanoscale, were optimized through a factorial analysis. The optimization allowed extending conversion yields of epoxy groups up to more than 90% in dilute amine solution within less than 4 hours of reaction for TEA addition. This ion-exchange support with respect to the in-situ light-addressable process of elaboration is specifically designed to be incorporated as biomolecular sample preparation module in microsystem devices. The high loading capacity obtained for the preconcentration of DNA demonstrate the attractivity of this functionalized polymeric porous monolith as solid-phase support to improve the quantity and the efficiency of DNA extraction applied into microscale format like capillaries or lab-on-chip

Are analytical standards and reagents really reliable ?

International audienceQuality assurance is one of the major challenges in analytical chemistry whatever the scope of application. The quality of analytical standards is never questioned, however sometimes odd results are obtained and all the other potential sources of discrepancies are eliminated. So, we investigated the quality of three analytical standards and reagents implemented for radiological and chemical characterizations of nuclear waste. In particular, this work examined the purity of a source of tritiated-labelled dodecane, the trueness and the purity of a DTPA reagent and the trueness of a multi-anions standard used for an intercomparison exercise. It was shown that the source of tritiated-labelled dodecane contains 60 per cent of tritiated-labelled impurities. The trueness of the DTPA concentration was questioned due to the presence of impurities in the solution. It was proven that the long-term stability of the multi-anions standard was not guaranteed for nitrite. The results clearly demonstrated that, although in opposition to intuition, cautiousness has to be taken towards the quality of the analytical standards

Analysis of twenty five impurities in uranium matrix by ICP-MS with iron measurement optimized by using reaction collision cell, cold plasma or medium resolution

International audienceAn analytical procedure was developed to determine the concentration of 25 impurities (Li, Be, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Ag, Cd, In, Sm, Eu, Gd, Dy, W, Pb, Bi and Th) in a uranium matrix using the quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS). The dissolution of U3O8 powder was made with a mixture of hydrochloric acid and nitric acid. Then, a selective separation of uranium using the UTEVA column was used before measurement by Q-ICP-MS. The procedure developed was verified using the Certified Reference Material “Morille”. The analytical results agree well except for 5 elements where values are underestimated (Li, Be, In, Pb and Bi). Among the list of impurities, iron was particularly investigated because it is well known that this element possesses a polyatomic interference that increases the detection limit. A comparison between iron detection limits obtained with different methods was performed. Iron polyatomic interference was at least reduced, or at best entirely resolved in some cases, by using the cold plasma or the collision/reaction cell with several gases (He, NH3 and CH4). High-resolution ICP-MS was used to compare the results obtained. A detection limit as low as 8ngL−1 was achieved