Can logistics compensate for the local effects of deindustrialisation? The situation in the Ile-de-France region between 1982 and 2012

Document CGE

Analysis of molecules of biological interest in supercritical chromatography and unified chromatography - Fundamental studies and applications

La SFC est une technique analytique ancienne qui a mis du temps à s’implanter dans les mœurs des chromatographistes, restant de longues années dans l’ombre de l’HPLC et la GC. Les petites molécules peu polaires s’analysent facilement grâce à cette technique du fait de la faible polarité du dioxyde de carbone. Qu’en est-il des composés polaires ? Plusieurs méthodes ont été mises en place afin de les analyser. Une technique intermédiaire entre la SFC et l’HPLC a été utilisée, la chromatographie unifiée.Ce travail de recherche traite de méthodes pour analyser des molécules de polarité plus élevée, tels que des acides aminés. Des phases stationnaires ont été étudiées grâce au modèle LSER pour comprendre le comportement de telles molécules dans un milieu supercritique. Un développement de méthode a été effectué pour l’analyse d’acides aminés. Cette méthode a ensuite été utilisée pour diverses applications (compléments alimentaires, plante d'intérêt pharmaceutique).SFC is an old analytical technique that took time to establish itself in the morals of chromatographers, remaining for many years in the shadow of HPLC and GC. Small and non-polar molecules are easily analysed using this technique because of the low polarity of carbon dioxide. What about polar compounds? Several methods can be used to analyse them. An intermediate technique between SFC and HPLC was used, unified chromatography.This research deals with methods for analysing molecules of higher polarity, such as amino acids. Stationary phases were studied using the LSER model to understand the behaviour of such molecules in a supercritical environment. A method development was performed for amino acid analysis. This method was then used for various applications (food supplements, plant of pharmaceutical interest)

Analyse de molécules d'intérêt biologique en chromatographie supercritique et chromatographie unifiée - Etudes fondamentales et applications

SFC is an old analytical technique that took time to establish itself in the morals of chromatographers, remaining for many years in the shadow of HPLC and GC. Small and non-polar molecules are easily analysed using this technique because of the low polarity of carbon dioxide. What about polar compounds? Several methods can be used to analyse them. An intermediate technique between SFC and HPLC was used, unified chromatography.This research deals with methods for analysing molecules of higher polarity, such as amino acids. Stationary phases were studied using the LSER model to understand the behaviour of such molecules in a supercritical environment. A method development was performed for amino acid analysis. This method was then used for various applications (food supplements, plant of pharmaceutical interest).La SFC est une technique analytique ancienne qui a mis du temps à s’implanter dans les mœurs des chromatographistes, restant de longues années dans l’ombre de l’HPLC et la GC. Les petites molécules peu polaires s’analysent facilement grâce à cette technique du fait de la faible polarité du dioxyde de carbone. Qu’en est-il des composés polaires ? Plusieurs méthodes ont été mises en place afin de les analyser. Une technique intermédiaire entre la SFC et l’HPLC a été utilisée, la chromatographie unifiée.Ce travail de recherche traite de méthodes pour analyser des molécules de polarité plus élevée, tels que des acides aminés. Des phases stationnaires ont été étudiées grâce au modèle LSER pour comprendre le comportement de telles molécules dans un milieu supercritique. Un développement de méthode a été effectué pour l’analyse d’acides aminés. Cette méthode a ensuite été utilisée pour diverses applications (compléments alimentaires, plante d'intérêt pharmaceutique)

Can logistics compensate for the local effects of deindustrialisation? The situation in the Ile-de-France region between 1982 and 2012

Document CGE

Can logistics compensate for the local effects of deindustrialisation? The situation in the Ile-de-France region between 1982 and 2012

Document CGE

Can logistics compensate for the local effects of deindustrialisation? The situation in the Ile-de-France region between 1982 and 2012

Document CGE

Hydrological classification by clustering approach of time-integrated samples at the outlet of the Rhône River: application to Δ14C-POC

International audienceWithin the framework of the Rhône Sediment Observatory, monthly time-integrated samples have been collected by Particle Traps (PT) in the last decade to monitor particulate contaminants in the Rhône River and its main tributaries. In this watershed with a very contrasted hydrology, we propose to use a clustering approach to classify the samples according to the main hydrological groups. This approach has been applied to riverine particulate organic radiocarbon signatures (Δ14C-POC) that are strongly affected by the origin of the material and the occurrence of nuclear plant releases. Suspended sediment samples were collected near the outlet of the Rhône River at Arles and analysed for 14C along with particulate organic carbon, chlorophyll a and tritium contents to confirm Δ14C-POC origins. Cluster Analyses (CA), coupled to Principal Component Analysis (PCA), were performed based on monthly average water discharges of the Upper Rhône River and the five main Rhône’s tributaries to define data sets according to their similarities. The classification obtained by fuzzy C-mean logic of the Rhône River hydrology into 5 clusters is similar to that already observed in the literature with Mediterranean/Cevenol floods, oceanic pluvial floods, nival floods, low-water levels and baseflows. The contribution of each cluster among the Δ14C-POC values demonstrate the complexity of hydrological classification of time-integrated sample. First, the samples with a unique and significantly dominant cluster are easily explained, with negative Δ14C-POC values observed in the flood clusters due to input from 14C-depleted material from soil or rock weathering, and positive values observed in the low-water level and baseflow clusters due to anthropogenic input by nuclear industry. Second, some samples present a homogeneous mixture between several clusters and demonstrate the occurrence of different hydrological events during the sampling periods. This tool appears as a solution to estimate the contribution of each hydrological event classification in time-integrated samples

Cinchona-based zwitterionic stationary phases: Exploring retention and enantioseparation mechanisms in supercritical fluid chromatography with a fragmentation approach

International audienceChiralpak ZWIX(+) and ZWIX(-), are brush-type bonded-silica chiral stationary phases (CSPs), based on complex diastereomeric Cinchona alkaloids derivatives bearing both a positive and a negative charge. In the present study, we aimed to improve the understanding of retention and enantioseparation mechanisms of these CSPs employed in supercritical fluid chromatography (SFC). For this purpose, 9 other stationary phases were used as comparison systems: two of them are commercially available and bear only a positive charge (Chiralpak QN-AX and QD-AX) and the 7 others were designed purposely to be structurally similar to the parent ZWIX phases, but miss some portion of the complex ligand. First, cluster analysis was employed to identify similar and dissimilar behavior among the 11 stationary phases, where ionic interactions appeared to dominate the observed differences. Secondly, the stationary phases were characterized with linear solvation energy relationships (LSER) based on the SFC analysis of 161 achiral analytes and a modified version of the solvation parameter model to include ionic interactions. This served to compare the interaction capabilities for the 11 stationary phases and showed in particular the contribution of attractive and repulsive ionic interactions. Then the ZWIX phases were characterized for their enantioseparation capabilities with a set of 58 racemic probes. Discriminant analysis was applied to explore the molecular structural features that are useful to successful enantioseparation on the ZWIX phases. In particular, it appeared that the presence of positive charges in the analyte is causing increased retention but is not necessarily a favorable feature to enantiorecognition. On the opposite, the presence of negative charges in the analyte favors early elution and enantiorecognition. Finally, a smaller set of 30 pairs of enantiomers, selected by their structural diversity and different enantioseparation values on the ZWIX phases, were analyzed on all chiral phases to observe the contribution of each structural fragment of the chiral ligand on enantioselectivity. Molecular modelling of the ligands also helped in understanding the three-dimensional arrangement of each ligand, notably the intra-molecular hydrogen bonding or the possible contribution of ionic interactions. In the end, each structural element in the ZWIX phases appeared to be a significant contributor to successful enantioresolution, whether they contribute as direct interaction groups (ion-exchange functions) or as steric constraints to orientate the interacting groups towards the analytes