58 research outputs found
Évaluation des procédés de dégradation de l’atrazine dans l’eau par décharges électriques et par ultrasons hautes fréquences : optimisation paramétrique et étude des mécanismes réactionnels
No full textL'objectif principal de la thèse est de développer une technologie efficace pour la dégradation des pesticides. L'herbicide atrazine a été étudié comme molécule modèle. L'atrazine a été dégradée dans l'eau par décharge électrique de haute tension (DEHT), et ses performances de dégradation ont été comparées aux technologies traditionnelles d'oxydation de Fenton et d'ultrasons (US). La détection et la quantification de l'atrazine et de ses métabolites ont été réalisées par chromatographie liquide haute performance et spectrométrie de masse à haute résolution (HPLC-HRMS). Une méthode d'analyse en ligne par HPLC-HRMS combinée à un échantillonnage automatique a été développée pour un suivi en temps réel du processus de dégradation. La technologie DEHT a dégradé efficacement l'atrazine et a réduit les métabolites toxiques générés au cours des processus d’oxydation de Fenton et d’US. Le procédé de DEHT est moins consommateur d'énergie que le procédé d’US tout en atteignant la même efficacité de dégradation de l'atrazine de 89%. Les mécanismes de dégradation de l'atrazine pour les différentes technologies ont été proposés. L'effet d'une matrice réelle (eau du robinet) par rapport à une matrice modèle (eau déminéralisée) sur la dégradation de l'atrazine a été étudié. Les résultats ont montré que dans le cas d’un traitement par DEHT, l'efficacité de dégradation de l'atrazine dans l'eau du robinet était inférieure à celle de l'eau déminéralisée, ce qui peut être lié à la conductivité de l'eau et au mécanisme de génération des arcs électriques dans un milieu conducteur. La toxicité aiguë (CL50) chez la daphnie Daphnia magna a été utilisée pour évaluer la toxicité des différentes solutions de traitement contenant initialement de l'atrazine. La toxicité de la solution d'atrazine traitée par oxydation de Fenton est supérieure à celle traitée par DEHT et US.The main goal of this thesis is to develop an efficient technology for the degradation of pesticides. For this purpose, the widely used herbicide atrazine was studied as a model molecule. Atrazine was degraded in water by high voltage electrical discharge (HVED), and its degradation performance was compared with traditional water treatment technologies Fenton oxidation and ultrasound (US). The detection and quantification of atrazine and its metabolites were achieved by high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS). An online analysis method by HPLC-HRMS combined with automatic sampling was developed for real-time monitoring of the degradation process. The HVED technology efficiently degraded atrazine and reduced toxic metabolites generated during Fenton oxidation and US processes. HVED process has less energy consumption than US process while achieving the same 89% atrazine degradation efficiency. The mechanism pathways of atrazine degradation for different technologies were proposed. The effect of real matrix (tap water) versus model matrix (deionized water) on atrazine degradation was studied. Results showed that in HVED treatment, the degradation efficiency of atrazine in tap water was lower than that in deionized water, which may be related to the conductivity of the water and to the mechanism of electric arcs generation in a conductive medium. The acute toxicity (LC50) in Daphnia magna was used to evaluate the toxicity of different treatment solutions initially containing atrazine. The toxicity of atrazine solution treated by Fenton oxidation is higher than that treated by HVED and US
SPACE NOTATION IN ELECTROACOUSTIC MUSIC: FROM GESTURE TO SIGNS
No full textInternational audienceThis article is based on an analysis of the functionalities of many devices and software used for sound spatialization, an original research about space perception modes and finally an in-depth study about musical notation systems. Theses studies lead the author to propose a notation system for spatialization activities, simply based on the paradigm of our Western classical music notation. Various examples illustrate the merits and versatility of this proposal. The present notation is both descriptive and prescriptive. Thus, a practical implementation based on MIDI standard also makes possible instrumental space performances, implementation of algorithmic processes, space writing and structuring, but also offers access to all the existing software such as MIDI sequencer, MIDI computing and score writing. The MIDISpat plug-in-developed by the author-has been used for many years inside of Reaper digital audio sequencer
13C labeling analysis of sugars by high resolution-mass spectrometry for metabolic flux analysis
No full textInternational audienceMetabolic flux analysis is particularly complex in plant cells because of highly compartmented metabolism. Analysis of free sugars is interesting because it provides data to define fluxes around hexose, pentose, and triose phosphate pools in different compartment. In this work, we present a method to analyze the isotopomer distribution of free sugars labeled with carbon 13 using a liquid chromatography ehigh resolution mass spectrometry, without derivatized procedure, adapted for Metabolic flux analysis. Our results showed a good sensitivity, reproducibility and better accuracy to determine isotopic en-richments of free sugars compared to our previous methods
Online monitoring of hepatic rat metabolism by coupling a liver biochip and a mass spectrometer
No full textA microfluidic liver biochip was coupled with a mass spectrometer to detect in real time the drug metabolism of hepatocytes.</p
Data documenting the comparison between the theoretically expected values of free sugars mass isotopomer composition with standards using GC–MS and LC-HRMS for Metabolic Flux Analysis
No full textThe data presented in this article are related to the research article entitled “13C labeling analysis of sugars by high resolution-mass spectrometry for Metabolic Flux Analysis” (Acket et al., 2017) [1]. This article provides data concerning the comparison between the theoretically expected values of free sugars mass isotopomer composition with standards using our previous methods using low resolution mass spectrometry by GC–MS (Koubaa et al., 2012, 2014) [2,3], and your new method using high resolution-mass spectrometry (LC-HRMS) for Metabolic Flux Analysis [1]. For discussion and a more comprehensive data interpretation and analysis, please refer to Acket et al. (2017) [1]
Real-Time Monitoring of the Atrazine Degradation by Liquid Chromatography and High-Resolution Mass Spectrometry: Effect of Fenton Process and Ultrasound Treatment
No full textHigh resolution mass spectrometry (HRMS) was coupled with ultra-high-performance liquid chromatography (uHPLC) to monitor atrazine (ATZ) degradation process of Fenton/ultrasound (US) treatment in real time. Samples were automatically taken through a peristaltic pump, and then analysed by HPLC-HRMS. The injection in the mass spectrometer was performed every 4 min for 2 h. ATZ and its degradation metabolites were sampled and identified. Online Fenton experiments in different equivalents of Fenton reagents, online US experiments with/without Fe2+ and offline Fenton experiments were conducted. Higher equivalents of Fenton reagents promoted the degradation rate of ATZ and the generation of the late-products such as Ammeline (AM). Besides, adding Fe2+ accelerated ATZ degradation in US treatment. In offline Fenton, the degradation rate of ATZ was higher than that of online Fenton, suggesting the offline samples were still reacting in the vial. The online analysis precisely controls the effect of reagents over time through automatic sampling and rapid detection, which greatly improves the measurement accuracy. The experimental set up proposed here both prevents the degradation of potentially unstable metabolites and provides a good way to track each metabolite
Evaluation of Performance and Validity Limits of Gas Chromatography electron ionization – Orbitrap Detector for fatty acid methyl esters analyses.
No full textInternational audienc
Degradation of Residual Herbicide Atrazine in Agri-Food and Washing Water
No full textInternational audienceAtrazine, an herbicide used to control grassy and broadleaf weed, has become an essential part of agricultural crop protection tools. It is widely sprayed on corn, sorghum and sugar cane, with the attendant problems of its residues in agri-food and washing water. If ingested into humans, this residual atrazine can cause reproductive harm, developmental toxicity and carcinogenicity. It is therefore important to find clean and economical degradation processes for atrazine. In recent years, many physical, chemical and biological methods have been proposed to remove atrazine from the aquatic environment. This review introduces the research works of atrazine degradation in aqueous solutions by method classification. These methods are then compared by their advantages, disadvantages, and different degradation pathways of atrazine. Moreover, the existing toxicological experimental data for atrazine and its metabolites are summarized. Finally, the review concludes with directions for future research and major challenges to be addressed
Degradation of herbicide atrazine in water by high voltage electrical discharge in comparison with Fenton oxidation and ultrasound treatments
No full textInternational audienceAtrazine, the most commonly used herbicide, has been reported to pollute the water environment and do harm to human health. It is thus urgent to find an efficient way to degrade atrazine. Although various advanced oxidation processes including high voltage electrical discharge (HVED) have been applied to degrade atrazine, the formation kinetics of its metabolites are still incomplete, and the detoxification of the degradation process remains to be clarified. Here, the degradation of atrazine by HVED was investigated, in comparison with traditional Fenton oxidation and ultrasound treatment. Nineteen metabolites of atrazine degradation were identified and quantified by high performance liquid chromatography coupled with high resolution mass spectrometry (HPLC-HRMS) techniques. Results show that HVED is more advantageous because of its high degradation rate for atrazine (89%), short processing time (1000 s, corresponding to 10 ms effective time), and the presence of the less toxic main metabolite hydroxyatrazine. Hydroxyl radicals (˙OH) play an important role in atrazine degradation. Adding ferrous ions (Fe2+) during HVED and ultrasound processes is beneficial for the degradation of atrazine, because of the ˙OH radicals released from hydrogen peroxide (H2O2). Based on the formation kinetics of atrazine degradation metabolites, detailed mechanisms of atrazine degradation pathways were proposed
Towards the use of a molecularly imprinted polymer in doping analysis :selective preconcentration and analysis of testosterone and epitestosterone in human urine
No full textInternational audienceA molecularly imprinted polymer (MIP), templated with methyltestosterone, has been synthesized for the cleanup of hydrolyzed urine samples for subsequent testosterone (T) quantification by LC−MS/MS. A concentration of 2 ng/mL testosterone could be quantified after a single step extraction on the MIP. The limit of detection and quantification with the criteria of a signal-to-noise ratio of 3 and 5 were 0.3 and 2 ng/mL, respectively. These values meet the conditions set by the World Anti-Doping Agency for the minimum required performance limits for doping controls, between 2 and 10 ng/mL. Epitestosterone (E) was also separated on this polymer and could be detected at concentrations down to 0.3 ng/mL. The quantification of T and E gives access to the determination of the T/E ratio, essential in doping analysis. Hence, our polymers can offer a more specific extraction procedure, resulting in increased sensitivity with limits of detection 10 times lower than the ones achieved by the standard SPE C18 sorbents employed in official testing laboratories
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