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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

High Flow Air Sampling for Field Detection Using Gas Chromatography-Mass Spectrometry

Murray, Jacolin Ann 01 December 2010 (has links) (PDF)
The ability to rapidly detect and identify hazardous analytes in the field has become increasingly important. One of the most important analytical detection methods in the field is gas chromatography-mass spectrometry (GC-MS). In this work, a hand-portable GC-MS system is described that contains a miniature toroidal ion trap mass analyzer and a low thermal mass GC. The system is self-contained within the dimensions of 47 x 36 x 18 cm and weighs less than 13 kg. Because the instrument has a small footprint, it was used as the detector for an automated near-real-time permeation testing system. In permeation testing, materials that are used to make individual protective equipment such as gloves, masks, boots, and suits are exposed to hazardous analytes to determine how long the equipment can be worn safely. The system described herein could test five samples simultaneously. A multi-position valve rotated among the various sample streams and delivered time aliquots into the MS for quantitation. Current field air sampling techniques suffer from long desorption times, high pressure drops, artifact formation and water retention. These disadvantages can be avoided by concentrating the analytes in short open tubular traps containing thick films. There are several advantages to using polymer coated capillaries as traps, including fast desorption, inertness and low flow restriction. An air sampling trap was constructed utilizing open tubular traps for the concentration of semi-volatile organic compounds. The system consisted of multiple capillary traps bundled together, providing high sample flow rates. The analytes were desorbed from the multi-capillary bundle and refocused in a secondary trap. The simultaneous focusing and separation effect of a trap subjected to a negative temperature gradient was also explored. In this configuration, analytes were focused because the front of the peak was at a lower temperature than the rear of the peak and, hence, moved slower. In addition to the focusing effect, analytes with different volatilities focused at different temperatures within the gradient, allowing for separation.
22

The Fate and Transport of Chemical Warfare Agent Simulants in Complex Matrices

Daphney, Cedrick M., 15 July 2008 (has links)
Experiments to determine the fate and transport of the chemical warfare agent (CWA) simulants diisopropyl fluorophosphate (DIFP), O,S-diethyl methylphosphonothioate (OSDEMP), and 2-Chloroethyl ethyl sulfide (CEES) exposed to complex matrix systems are reported here. The aforementioned simulants were used in place of O-isopropyl methylphosphonofluoridate (GB), O-Ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX), and Bis (2-chloroethyl) sulfide (HD), respectively. At ambient temperature, simulant pH (2.63 to 12.01) and reaction time (1 minute to 24 hours) were found to have significant influence on the recovery of simulants from charcoal, plastic, and TAP (butyl rubber gloves) in aqueous media. Buffer systems used included, phosphate, acetate, borate, and disodium tetraborate. Organic extractions were carried out using a 90:10 (v/v) dichloromethane / 2-propanol solution. All extracts were analyzed with a gas chromatograph equipped with flame ionization and flame photometric detectors (GC-FID-FPD). The FPD was used to determine the amount of simulant recovery.
23

Formulation et évaluation de la stabilité et de l’efficacité de topiques protecteurs vis-à-vis des composés organophosphorés / Formulation and assessment of stability and efficacy of topical skin protectant against organophosphorus compounds

Millerioux, Jennifer 20 March 2009 (has links)
Les neurotoxiques organophosphorés (NOP) sont extrêmement toxiques et peu volatils. Dans des conditions normales de température et de pression, ils peuvent pénétrer rapidement la peau sous forme liquide et exercer leurs effets délétères. En milieu civil ou militaire, leur utilisation potentielle est toujours redoutée. Le développement de dispositifs de protection cutanée vis-à-vis de ces agents est donc d’un intérêt majeur pour les armées et la sécurité civile. Dans ce contexte, les objectifs de ce travail ont été de formuler et évaluer la stabilité et l’efficacité de topiques protecteurs cutanés (TP) vis-à-vis des NOP. Le premier objectif a consisté à mettre au point des TP de compositions et de formes galéniques différentes (émulsions, gels) puis à valider leurs stabilités physicochimiques. Cent trente TP ont été formulés et 30 ont montré une stabilité physicochimique satisfaisante. Le second objectif a été d’évaluer l’efficacité des TP les plus prometteurs vis-à-vis des composés organophosphorés. Actuellement il n’existe pas de standardisation de ce type d’étude. Par conséquent, l’utilisation de plusieurs tests in vitro et in vivo (membranes biologiques ou synthétiques, NOP ou simili), dont la pertinence et la fiabilité ont été déterminées, nous a permis d’établir une logique de criblage pour l’évaluation de l’efficacité des TP. Parmi les 13 formulations testées, les résultats ont montré qu’un gel hydro-alcoolique apporte une protection cutanée significative et supérieure aux produits de référence testés vis-à-vis du VX, un NOP d’intérêt / Prevention of exposure to the neurotoxic organophosphorus compounds (OP) that are quickly absorbed in the skin is a major concern both for pesticide users and soldiers. Skin barrier creams are being developed to complement or replace uncomfortable chemical protective suits. The objectives of this work were to formulate and assess physicochemical stability and protective efficacy of topical skin protectant (TSP) against OP compounds. The first objective was to formulate several different TSP (emulsions, gel) and validate their physicochemical stability.The second objective was to determine the consistency of results from in vitro tests and the importance of the formulation composition in the skin protective efficacy. Quick evaluation of formulations efficacy mainly relies on in vitro tests which lead to consistent, complementary and relevant results. Our results indicated that the least effective formulations could be quickly identified by performing in vitro permeation tests with silicone membrane and by evaluating interfacial interactions between formulations and OP. We showed that a hydrogel containing specific hydrophilic polymers was by far the most effective of the formulations evaluated against VX, OP compounds, skin permeation in vitro
24

Hapsite (R) gas chromatography - mass spectrometry with solid phase microextraction /

Kan, WaiKwong. January 2005 (has links) (PDF)
Thesis (M.S.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).
25

Field and laboratory application of a gas chromatograph low thermal mass resistively heated column system in detecting traditional and non-traditional chemical warfare agents using solid phase micro-extraction /

Koch, David R. January 2005 (has links) (PDF)
Thesis (M.S.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).
26

Chemical vapor identification using field-based attenuated total reflectance Fourier transform infrared detection and solid phase microextraction /

Bryant, Chet Kaiser. January 2005 (has links) (PDF)
Thesis (M.S.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).
27

Připravenost Zdravotnické záchranné služby hl. m. Prahy na zásah při chemické hrozbě v metru / Prague Emergency Medical Services Preparedness for Medical Intervention During Chemical Threat in Metro

TEJKL, Miroslav January 2017 (has links)
The goal of this theses is to analyse the preparedness of Prague Emergency Medical Services (hereinafter Prague EMS) for chemical attack in subway (metro). The theoretical part states general information about chemical terrorism and the Integrated Rescue System's solution. The research part focuses on procedures following from Integrated Rescue System Common Type Activity during joint action - Reaction on chemical attack in subway (hereinafter STČ 13/IZS). This document was subjected to content analysis to meet the goals. The work then focuses on the evaluation of Prague EMS training Metro 2014 whose goal was to practice the procedures and joint deployment of Integrated Rescues System members and other subject according to STČ 13/IZS. For the evaluation complexity, the results were supplemented by SWOT analysis which pointed at another usable knowledge. All conclusions are clearly organized in charts and they are efficiently worked with to set new measures and recommendations which would increase the preparedness of Prague EMS for chemical attack in metro. The goal of this work to assess the level of preparedness and to submit final protocol to organisation's crisis management was fulfilled. The main benefit of this work is a recommendation for the reinforcement of crisis preparedness at Prague EMS. Furthermore the work brings new expert findings to solved problematics.
28

Historie chemických válek / The history of chemical wars

HORKÁ, Jana January 2007 (has links)
Chemical weapons count among the weapons of mass destruction. In addition to chemical weapons, also nuclear and biological weapons belong here. Historically, chemical weapons rank among the oldest ones. Their initial steps were made in the distant past, even if they were not called so then. However, the initial utilization of chemical agents against human force is more connected with fire. It was used for protection against attacks of animals as well as people. Later on it was used to protect or capture towns and fortifications. The most extensive use of chemical weapons in war occurred during World War I. A large number of chemical substances was tested, the most important being phosgene. In 1917, German army used vesicant yperite near the town of Ypres. The development of chemical warfare agents continued also after the year 1918. During World War II, chemical weapons were practically not used. If it happened, then on the secondary fronts only. The main reason was the fear of possible retaliation. From 1939 to 1945, huge amounts of chemical warfare agents were made. Towards the end of the war this stockpile amounted to approximately 400 000 tonnes. After World War II, a new stage of chemical armament has begun. The greatest attention was concentrated on nerve agents, sarin, soman and agent VX. Chemical warfare agents have been further used also after the year 1945. In the not so distant past, Iraq used nerve-paralyzing agents and yperite during the Iran-Iraq War (1980 {--} 1988). Last but not least, the use of chemical warfare agents for terrorist purposes is to be mentioned. In January 1993, the global fight against chemical weapons culminated in signing of the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction. Under this Convention, chemical weapons were to be liquidated until the year 2007. States Parties to the Chemical Weapons Convention which did not comply with this deadline have asked for prolongation of the final deadlines for chemical weapons liquidation until 29 April 2012. The question remains if even this prolongation will fulfil the goal of the Convention {--} to ensure a world without chemical weapons. Until the time when the stockpiles of chemical weapons are completely liquidated their possible misuse cannot be excluded. The states which have not joined the Convention as yet and own limited stockpiles of chemical weapons can use them.
29

Application of solid phase microextraction with gas chromatography-mass spectrometry as a rapid, reliable, and safe method for field sampling and analysis of chemical warfare agent precursors /

Parrish, Douglas K. January 2005 (has links) (PDF)
Thesis (Ph. D.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).
30

Hapsite® gas chromatograph-mass spectrometer (GC/MS) variability assessment /

Skinner, Michael A. January 2005 (has links) (PDF)
Thesis (M.S.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).

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