CONTRIBUTION A L'AMELIORATION DE L'ANALYSE DE LA FRACTION VOLATILE DE PRODUITS RICHES EN EAU PAR ESPACE DE TETE DYNAMIQUE COUPLE A LA CHROMATOGRAPHIE EN PHASE GAZEUSE ET SPECTROMETRIE DE MASSE PDF Download
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Author: DELPHINE.. CANAC ARTEAGA
Publisher:
ISBN:
Category :
Languages : fr
Pages : 137
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L'OBJECTIF DE CE TRAVAIL ETAIT DE METTRE EN UVRE DES PROCEDES ANALYTIQUES PERMETTANT DE LIMITER LES ARTEFACTS DUS A L'EAU LORS DE L'ANALYSE DE LA FRACTION VOLATILE DE PRODUITS RICHES EN EAU PAR ESPACE DE TETE DYNAMIQUE - CHROMATOGRAPHIE EN PHASE GAZEUSE ET SPECTROMETRIE DE MASSE. TOUT D'ABORD, DES PROCEDURES REPUTEES APTES A REDUIRE CES ARTEFACTS ONT ETE TESTEES AFIN DE DECRIRE LEURS EFFETS SUR LES ANALYSES D'UN FROMAGE. CES PROCEDURES CONSISTAIENT A ELIMINER L'EAU AU NIVEAU DU PIEGE PAR UNE ETAPE DE DRY-PURGE, A CONDENSER L'EAU PAR UN PIEGE FROID OU A DIMINUER L'ACTIVITE DE L'EAU DE L'ECHANTILLON PAR AJOUT DE SELS HYGROSCOPIQUES. ENSUITE DES ARTEFACTS ANALYTIQUES ONT ETE INDUITS PAR INTRODUCTION DE VAPEUR D'EAU DANS L'ESPACE DE TETE DE PRODUITS SECS AFIN DE LOCALISER LEUR ORIGINE DANS LA CHAINE ANALYTIQUE. ENFIN, LA PREPARATION DE L'ECHANTILLON PAR ULTRA-CENTRIFUGATION A ETE TESTEE AFIN D'EXTRAIRE SA PHASE LIPIDIQUE. LES SOLUTIONS TESTEES ONT PERMIS D'AMELIORER LA QUALITE DU SIGNAL CHROMATOGRAPHIQUE (DIMINUTION DU BRUIT ANALYTIQUE, AMELIORATION DE LA FORME DES PICS, ABSENCE DE TRAINEES) EN LIMITANT L'INTRODUCTION D'EAU DANS LE CIRCUIT ANALYTIQUE, MAIS AVAIENT POUR INCONVENIENT DE MODIFIER LES PROFILS CHROMATOGRAPHIQUES DU PRODUIT ETUDIE (CHANGEMENT DES PROPORTIONS ENTRE LES COMPOSES, DISPARITIONS OU APPARITIONS DE CERTAINS PICS). LES ARTEFACTS ANALYTIQUES MIS EN EVIDENCE ETAIENT PRINCIPALEMENT DUS A DES MECANISMES DE COMPETITION ENTRE L'EAU ET LES MOLECULES VOLATILES AU NIVEAU DE L'ADSORBANT. LA PHASE LIPIDIQUE OBTENUE PAR ULTRACENTRIFUGATION A ETE CHAUFFEE A 80\C LORS DE L'ANALYSE AFIN D'AMELIORER L'EXTRACTION DES COMPOSES VOLATILS. CETTE METHODE A ETE APPLIQUEE AU DOSAGE DES MOLECULES TERPENIQUES DANS UN FROMAGE.
Author: DELPHINE.. CANAC ARTEAGA
Publisher:
ISBN:
Category :
Languages : fr
Pages : 137
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Book Description
L'OBJECTIF DE CE TRAVAIL ETAIT DE METTRE EN UVRE DES PROCEDES ANALYTIQUES PERMETTANT DE LIMITER LES ARTEFACTS DUS A L'EAU LORS DE L'ANALYSE DE LA FRACTION VOLATILE DE PRODUITS RICHES EN EAU PAR ESPACE DE TETE DYNAMIQUE - CHROMATOGRAPHIE EN PHASE GAZEUSE ET SPECTROMETRIE DE MASSE. TOUT D'ABORD, DES PROCEDURES REPUTEES APTES A REDUIRE CES ARTEFACTS ONT ETE TESTEES AFIN DE DECRIRE LEURS EFFETS SUR LES ANALYSES D'UN FROMAGE. CES PROCEDURES CONSISTAIENT A ELIMINER L'EAU AU NIVEAU DU PIEGE PAR UNE ETAPE DE DRY-PURGE, A CONDENSER L'EAU PAR UN PIEGE FROID OU A DIMINUER L'ACTIVITE DE L'EAU DE L'ECHANTILLON PAR AJOUT DE SELS HYGROSCOPIQUES. ENSUITE DES ARTEFACTS ANALYTIQUES ONT ETE INDUITS PAR INTRODUCTION DE VAPEUR D'EAU DANS L'ESPACE DE TETE DE PRODUITS SECS AFIN DE LOCALISER LEUR ORIGINE DANS LA CHAINE ANALYTIQUE. ENFIN, LA PREPARATION DE L'ECHANTILLON PAR ULTRA-CENTRIFUGATION A ETE TESTEE AFIN D'EXTRAIRE SA PHASE LIPIDIQUE. LES SOLUTIONS TESTEES ONT PERMIS D'AMELIORER LA QUALITE DU SIGNAL CHROMATOGRAPHIQUE (DIMINUTION DU BRUIT ANALYTIQUE, AMELIORATION DE LA FORME DES PICS, ABSENCE DE TRAINEES) EN LIMITANT L'INTRODUCTION D'EAU DANS LE CIRCUIT ANALYTIQUE, MAIS AVAIENT POUR INCONVENIENT DE MODIFIER LES PROFILS CHROMATOGRAPHIQUES DU PRODUIT ETUDIE (CHANGEMENT DES PROPORTIONS ENTRE LES COMPOSES, DISPARITIONS OU APPARITIONS DE CERTAINS PICS). LES ARTEFACTS ANALYTIQUES MIS EN EVIDENCE ETAIENT PRINCIPALEMENT DUS A DES MECANISMES DE COMPETITION ENTRE L'EAU ET LES MOLECULES VOLATILES AU NIVEAU DE L'ADSORBANT. LA PHASE LIPIDIQUE OBTENUE PAR ULTRACENTRIFUGATION A ETE CHAUFFEE A 80\C LORS DE L'ANALYSE AFIN D'AMELIORER L'EXTRACTION DES COMPOSES VOLATILS. CETTE METHODE A ETE APPLIQUEE AU DOSAGE DES MOLECULES TERPENIQUES DANS UN FROMAGE.
Author: MUSTAPHA.. NEDJMA
Publisher:
ISBN:
Category :
Languages : fr
Pages : 196
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CERTAINS COMPOSES SOUFRES SONT RESPONSABLES DE L'ALTERATION PLUS AU MOINS GRAVE DES QUALITES ORGANOLEPTIQUES DES BOISSONS ALCOOLISEES. EN PLUS DE LEUR CARACTERE NAUSEABOND, ILS POSSEDENT DES SEUILS DE PERCEPTION EXTREMEMENT FAIBLES. LEURS CONCENTRATIONS DANS LES VINS, LES BIERES ET LES SPIRITUEUX SONT GENERALEMENT DE L'ORDRE DE DIZAINES DE G/L VOIRE DU G/L. CES FAIBLES TENEURS RENDENT LEUR QUANTIFICATION DIFFICILE. LE TRAVAIL PRESENTE DANS CETTE THESE CONCERNE: - L'OPTIMISATION PAR CHROMATOGRAPHIE EN PHASE GAZEUSE DE L'ANALYSE DES PRODUITS SOUFRES VOLATILS PAR LA TECHNIQUE DE L'ESPACE DE TETE STATIQUE AVEC DETECTION PAR CHIMILUMINESCENCE (S.C.D.355). - LA MISE EN EVIDENCE D'UN EFFET DE MATRICE DANS LES MILIEUX COMPLEXES COMME LES VINS ET LES EAUX-DE-VIE, POUVANT MASQUER TOTALEMENT LA PRESENCE DE PRODUITS SOUFRES VOLATILS COMME LES THIOLS LORS DE L'ANALYSE PAR CHROMATOGRAPHIE EN PHASE GAZEUSE. - LA REACTIVITE DU SULFURE D'HYDROGENE VIS-A-VIS DES THIOLS EN PRESENCE DE CUIVRE (II), QUI CONDUIT A LA FORMATION DE TRISULFURES SYMETRIQUES ET MIXTES NAUSEABONDS. - LA FORMATION DE METHANETHIOL, DE DIMETHYLDISULFURE, DE THIOACETATE DE S-METHYLE ET DE DIMETHYLTRISULFURE LORS DES DEGRADATIONS THERMIQUE ET PHOTOCHIMIQUE DE DEUX INSECTICIDES UTILISES DANS LES TRAITEMENTS PHYTOSANITAIRES DE LA VIGNE (METHOMYL ET THIODICARBE). - L'APPARITION DU SULFURE DE CARBONYLE ET DU SULFURE DE CARBONE PAR L'HYDROLYSE ET LA PHOTODECOMPOSITION D'UN FONGICIDE (THIRAME)
Author: Ahmed Belasri
Publisher: Springer Nature
ISBN: 9811554447
Category : Technology & Engineering
Languages : en
Pages : 659
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Book Description
This book highlights peer reviewed articles from the 1st International Conference on Renewable Energy and Energy Conversion, ICREEC 2019, held at Oran in Algeria. It presents recent advances, brings together researchers and professionals in the area and presents a platform to exchange ideas and establish opportunities for a sustainable future. Topics covered in this proceedings, but not limited to, are photovoltaic systems, bioenergy, laser and plasma technology, fluid and flow for energy, software for energy and impact of energy on the environment.
Author: Bernard Hussler
Publisher:
ISBN:
Category :
Languages : fr
Pages :
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Author: National Research Council
Publisher: National Academies Press
ISBN: 0309170435
Category : Nature
Languages : en
Pages : 241
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Book Description
Having safe drinking water is important to all Americans. The Environmental Protection Agency's decision in the summer of 2001 to delay implementing a new, more stringent standard for the maximum allowable level for arsenic in drinking water generated a great deal of criticism and controversy. Ultimately at issue were newer data on arsenic beyond those that had been examined in a 1999 National Research Council report. EPA asked the National Research Council for an evaluation of the new data available. The committee's analyses and conclusions are presented in Arsenic in Drinking Water: 2001 Update. New epidemiological studies are critically evaluated, as are new experimental data that provide information on how and at what level arsenic in drinking water can lead to cancer. The report's findings are consistent with those of the 1999 report that found high risks of cancer at the previous federal standard of 50 parts per billion. In fact, the new report concludes that men and women who consume water containing 3 parts per billion of arsenic daily have about a 1 in 1,000 increased risk of developing bladder or lung cancer during their lifetime.
Author: Gerald G. Moy
Publisher: Springer
ISBN: 9781493939091
Category : Technology & Engineering
Languages : en
Pages : 0
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Unless a food is grossly contaminated, consumers are unable to detect through sight or smell the presence of low levels of toxic chemicals in their foods. Furthermore, the toxic effects of exposure to low levels of chemicals are often manifested slowly, sometimes for decades, as in the case of cancer or organ failure. As a result, safeguarding food from such hazards requires the constant monitoring of the food supply using sophisticated laboratory analysis. While the food industry bears the primary responsibility for assuring the safety of its products, the overall protection of people’s diets from chemical hazards must be considered one of the most important public health functions of any government. Unfortunately, many countries do not have sufficient capability and capacity to monitor the exposure of their populations to many potentially toxic chemicals that could be present in food and drinking water. Without such monitoring, public health authorities in many countries are not able to identify and respond to problems posed by toxic chemicals, which may harm their population and undermine consumer confidence in the safety of the food supply. From a trade perspective, those countries that cannot demonstrate that the food they produce is free of potentially hazardous chemicals will be greatly disadvantaged or even subject to sanctions in the international marketplace. The goal of a total diet study (TDS) is to provide basic information on the levels and trends of exposure to chemicals in foods as consumed by the population. In other words, foods are processed and prepared as typical for a country before they are analyzed in order to better represent actual dietary intakes. Total diet studies have been used to assess the safe use of agricultural chemicals (e.g., pesticides, antibiotics), food additives (e.g., preservatives, sweetening agents), environmental contaminants (e.g., lead, mercury, arsenic, cadmium, PCBs, dioxins), processing contaminants (e.g., acrylamide, polycyclic aromatic hydrocarbons, chloropropanols), and natural contaminants (e.g., aflatoxin, patulin, other mycotoxins) by determining whether dietary exposure to these chemicals are within acceptable limits. Total diet studies can also be applied to certain nutrients where the goal is to assure intakes are not only below safe upper limits, but also above levels deemed necessary to maintain good health. International and national organizations, such as the World Health Organization, the European Food Safety Agency and the US Food and Drug Administration recognize the TDS approach as one of the most cost-effective means of protecting consumers from chemicals in food, for providing essential information for managing food safety, including food standards, and for setting priorities for further investment and study. Total Diet Studies introduces the TDS concept to a wider audience and presents the various steps in the planning and implementation of a TDS. It illustrates how TDSs are being used to protect public health from chemicals in the food supply in many developed and developing countries. The book also examines some of the applications of TDSs to specific chemicals, including contaminants and nutrients.
Author: Gábor Földiák
Publisher:
ISBN: 9780444416995
Category :
Languages : en
Pages : 564
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Author: Universidade de Coimbra
Publisher:
ISBN: 9789892021577
Category : Fire weather
Languages : en
Pages : 355
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