Parmi les systèmes dédiés à l’analyse directe des solides, la vaporisation électrothermique occupe une place de choix. Elle offre plusieurs avantages. Le temps de préparation des échantillons est considérablement réduit. Il n’y a pas de dilution induite par la minéralisation et les risques de pertes ou de contaminations durant cette étape sont éliminés. Son principe de fonctionnement consiste à transformer, par chauffage, quelques milligrammes d’échantillon en un aérosol, qui est ensuite transporté dans un spectromètre d’émission atomique par plasma à couplage inductif, où la composition élémentaire est mesurée. Une première étude fondamentale a permis de mieux comprendre la dynamique de l’aérosol formé et de définir les meilleures conditions opératoires. L’utilisation de cette technique pour la détermination élémentaire dans les végétaux a présenté cependant des difficultés supplémentaires : difficulté d’étalonnage, effets de matrice et grandes variabilités sur les concentrations mesurées. L’utilisation d’un support de cellulose pour les solutions étalons a permis d’harmoniser les conditions de formation de l’aérosol pour l’échantillon et pour l’étalon, et d’obtenir ainsi des résultats justes. Les effets de matrices ont pu être considérablement réduits par une calcination préalable des échantillons. Le manque de précision des mesures, causée par le manque d’homogénéité des échantillons, a pu être limitée en de réduisant significativement la taille des particules solides. Ces résultats obtenus sur des poudres ont permis d’autres applications comme l’analyse d’échantillons entiers ou la cartographie de la composition chimique d’organes végétaux. / Among the systems dedicated to the direct analysis of the solids, electrothermal vaporization takes up a place of choice. It offers several advantages. The preparation time of the samples is considerably reduced. There is no dilution induced by the digestion and the risks of losses or contaminations during this stage are eliminated. Its functioning consists to convert, by heating, a few milligrams of sample into an aerosol which is then transported in an inductively coupled plasma atomic emission spectrometer, where the elemental composition of the sample is determinate. A first fundamental study allowed to better understand the dynamics of the formed aerosol and to define the best operating conditions. However, the use of this technique to determine the elemental composition of solid plant samples presented additional difficulties: difficulty of calibration, matrix effects and important imprecision on the measured concentrations. The use of a cellulose support for the standard solutions allowed to harmonize the formation of the aerosol between the sample and the standard, and to obtain accurate results. The matrix effects can be considerably reduced by a preliminary dry-ashing of the samples. The variability of measurements, caused by the lack of homogeneity of the samples, was limited by reducing significantly the size of the solid particles. These results, obtained on powders, allowed other applications as the analysis of whole plant samples or the imaging of the chemical composition of plant organs.

Poon Lok-man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 126-128). / Abstracts in English and Chinese. / ABSTRACT --- p.ii / ACKNOWLEDGEMENT --- p.v / LIST OF TABLES --- p.vi / LIST OF FIGURES --- p.vii / GLOSSARY --- p.viii / Chapter CHAPTER 1: --- INTRODUCTION --- p.1 / Chapter CHAPTER 2: --- AIR POLLUTANTS AND ENVIRONMENTAL MONITORING --- p.8 / Chapter CHAPTER 3: --- PRINCIPLE OF LEAD FINGERPRINTING --- p.15 / Chapter CHAPTER 4: --- INSTRUMENTATION AND THEORY --- p.20 / Chapter CHAPTER 5: --- OPTIMIZATION OF ANALYTICAL PERFORMANCE IN LEAD ISOTOPE ANALYSIS --- p.29 / Chapter CHAPTER 6: --- DETERMINATION OF LEAD CONTENTS AND ISOTOPIC RATIOS IN POTENTIAL AIRBORNE LEAD SOURCES --- p.55 / Chapter CHAPTER 7: --- DETERMINATION OF LEAD CONTENT IN PARTICULATES COLLECTED ONTO HV-FILTERS --- p.69 / Chapter CHAPTER 8: --- ENVIRONMENTAL SURVEY --- p.74 / Chapter CHAPTER 9: --- "CONCLUSIONS, LIMITATIONS AND FURTHER DIRECTION" --- p.97 / APPENDICES --- p.105 / BIBLIOGRAPHY --- p.126

The scientific progress about the important chemotherapeutic drug substance cisplatin (CDDP) and its function has often been rendered by data difficult to interpret, and still many questions about its mode of action remains to be clarified by the scientific community. However, studies of CDDP possess a high complexity due to; i) low intracellular concentration, ii) many potential biomolecule targets, iii) poor or unknown stability of the intact drug and its biomolecule adducts and iv) complex and varying sample matrices. Metallomic studies, using advanced analytical techniques may contribute to clarify the interactions between CDDP and intracellular biomolecules. For a successful outcome sample preparation conditions as well as separation and detection techniques must be carefully selected and optimized to achieve accurate results and correct interpretation of data.         This thesis describes some new and improved analytical methodologies for characterizing the Pt metallome in CDDP-exposed malignant cells. The developed methods are based on powerful liquid chromatography (LC) methods hyphenated to sensitive detection by inductively coupled plasma- (ICP) and electrospray ionization mass spectrometry (ESIMS). Consideration has also been taken about sample preparation conditions.         By selecting “chemically inert” sample preparation (cell lysis by osmosis) and separation (using only nonreactive or no additatives) conditions we could avoid the formation of platinum artifact compounds previously described in the literature (Paper I and II). Using oxygen containing organic solvents with high boiling points (dimethylformamide; DMF, 1,4-dioxane, n-propanol and ethanol) as alternatives to acetonitrile in the LC separations, significant improvements were achieved in ICPMS sensitivity and robustness. When evaluated in combination with chromatographic performance and ESIMS detection the overall best performance was achieved with n-propanol (Paper II, III and IV). From the studies in Paper II we could show that free intact CDDP can be found in malignant cells, as supporting evidence for passive or endocytotic uptake of the drug and further estimate a half-life for intracellular CDDP to about 15 minutes. Such data has not been shown before. In Paper V, the above improved LC methods were used to demonstrate differences in the platinum and cupper metallome from sensitive and resistant T289 melanoma cells exposed to CDDP at near clinical levels.         In a wider perspective we have shown the potential of using hydrophilic liquid interaction chromatography (HILIC) hyphenated to ICPMS detection as a general approach for analysis of hydrophilic metallo-compounds (Paper II). Taking advantage of the superior ICPMS performance using n-propanol gradients for reversed phase liquid chromatography (RPLC) possess a true alternative and /or complimentary technique to size exclusion chromatography (SEC) commonly applied within metallomic studies of biomolecules (Paper V). Using n-propanol in HILIC as well as in RPLC enables parallel detection by ICP- and ESIMS using only one set of chromatographic parameters (Paper III and IV), something commonly called for by scientists in the field.

In modern low pressure plasma discharges, the electron mean free path often exceeds the device dimensions. Under such conditions the electron velocity distribution function may significantly deviate from Maxwellian, which strongly affects the discharge properties. The description of such plasmas has to be kinetic and often requires the use of numerical methods. This thesis presents the study of kinetic effects in inductively coupled plasmas and Hall thrusters carried out by means of particle-in-cell simulations. The important result and the essential part of the research is the development of particle-in-cell codes. <p>An advective electromagnetic 1d3v particle-in-cell code is developed for modelling the inductively coupled plasmas. An electrostatic direct implicit 1d3v particle-in-cell code EDIPIC is developed for plane geometry simulations of Hall thruster plasmas. The EDIPIC code includes several physical effects important for Hall thrusters: collisions with neutral atoms, turbulence, and secondary electron emission. In addition, the narrow sheath regions crucial for plasma-wall interaction are resolved in simulations. The code is parallelized to achieve fast run times. <p>Inductively coupled plasmas sustained by the external RF electromagnetic field are widely used in material processing reactors and electrodeless lighting sources. In a low pressure inductive discharge, the collisionless electron motion strongly affects the absorption of the external electromagnetic waves and, via the ponderomotive force, the density profile. The linear theory of the anomalous skin effect based on the linear electron trajectories predicts a strong decrease of the ponderomotive force for warm plasmas. Particle-in-cell simulations show that the nonlinear modification of electron trajectories by the RF magnetic field partially compensates the effects of electron thermal motion. As a result, the ponderomotive force in warm collisionless plasmas is stronger than predicted by linear kinetic theory. <p>Hall thrusters, where plasma is maintained by the DC electric field crossed with the stationary magnetic field, are efficient low-thrust devices for spacecraft propulsion. The energy exchange between the plasma and the wall in Hall thrusters is enhanced by the secondary electron emission, which strongly affects electron temperature and, subsequently, thruster operation. Particle-in-cell simulations show that the effect of secondary electron emission on electron cooling in Hall thrusters is quite different from predictions of previous fluid studies. Collisionless electron motion results in a strongly anisotropic, nonmonotonic electron velocity distribution function, which is depleted in the loss cone, subsequently reducing the electron wall losses compared to Maxwellian plasmas. Secondary electrons form two beams propagating between the walls of a thruster channel in opposite radial directions. The secondary electron beams acquire additional energy in the crossed external electric and magnetic fields. The energy increment depends on both the field magnitudes and the electron flight time between the walls. <p>A new model of secondary electron emission in a bounded plasma slab, allowing for emission due to the counter-propagating secondary electron beams, is developed. It is shown that in bounded plasmas the average energy of plasma bulk electrons is far less important for the space charge saturation of the sheath than it is in purely Maxwellian plasmas. A new regime with relaxation oscillations of the sheath has been identified in simulations. Recent experimental studies of Hall thrusters indirectly support the simulation results with respect to the electron temperature saturation and the channel width effect on the thruster discharge.

Obsidian has been a center of interest both for geologists and archaeologists. Geologists have studied on physical and chemical properties of obsidian where archaeologists have worked on this material as a common artifact found in excavations. In this study, obsidian samples from &Ccedil / atalh&ouml / y&uuml / k excavations are examined using their rare earth element (REE) concentrations. Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) have been used for this purpose. A mixture (4:1) of lithium metaborate and lithium tetraborate was used for fusion of samples. Because of the low concentrations of REEs, a preconcentration step is needed. Successful recovery results have been achieved with Amberlite IR-120. The developed method is tested using the standard reference material SARM-1.

In modern low pressure plasma discharges, the electron mean free path often exceeds the device dimensions. Under such conditions the electron velocity distribution function may significantly deviate from Maxwellian, which strongly affects the discharge properties. The description of such plasmas has to be kinetic and often requires the use of numerical methods. This thesis presents the study of kinetic effects in inductively coupled plasmas and Hall thrusters carried out by means of particle-in-cell simulations. The important result and the essential part of the research is the development of particle-in-cell codes. <p>An advective electromagnetic 1d3v particle-in-cell code is developed for modelling the inductively coupled plasmas. An electrostatic direct implicit 1d3v particle-in-cell code EDIPIC is developed for plane geometry simulations of Hall thruster plasmas. The EDIPIC code includes several physical effects important for Hall thrusters: collisions with neutral atoms, turbulence, and secondary electron emission. In addition, the narrow sheath regions crucial for plasma-wall interaction are resolved in simulations. The code is parallelized to achieve fast run times. <p>Inductively coupled plasmas sustained by the external RF electromagnetic field are widely used in material processing reactors and electrodeless lighting sources. In a low pressure inductive discharge, the collisionless electron motion strongly affects the absorption of the external electromagnetic waves and, via the ponderomotive force, the density profile. The linear theory of the anomalous skin effect based on the linear electron trajectories predicts a strong decrease of the ponderomotive force for warm plasmas. Particle-in-cell simulations show that the nonlinear modification of electron trajectories by the RF magnetic field partially compensates the effects of electron thermal motion. As a result, the ponderomotive force in warm collisionless plasmas is stronger than predicted by linear kinetic theory. <p>Hall thrusters, where plasma is maintained by the DC electric field crossed with the stationary magnetic field, are efficient low-thrust devices for spacecraft propulsion. The energy exchange between the plasma and the wall in Hall thrusters is enhanced by the secondary electron emission, which strongly affects electron temperature and, subsequently, thruster operation. Particle-in-cell simulations show that the effect of secondary electron emission on electron cooling in Hall thrusters is quite different from predictions of previous fluid studies. Collisionless electron motion results in a strongly anisotropic, nonmonotonic electron velocity distribution function, which is depleted in the loss cone, subsequently reducing the electron wall losses compared to Maxwellian plasmas. Secondary electrons form two beams propagating between the walls of a thruster channel in opposite radial directions. The secondary electron beams acquire additional energy in the crossed external electric and magnetic fields. The energy increment depends on both the field magnitudes and the electron flight time between the walls. <p>A new model of secondary electron emission in a bounded plasma slab, allowing for emission due to the counter-propagating secondary electron beams, is developed. It is shown that in bounded plasmas the average energy of plasma bulk electrons is far less important for the space charge saturation of the sheath than it is in purely Maxwellian plasmas. A new regime with relaxation oscillations of the sheath has been identified in simulations. Recent experimental studies of Hall thrusters indirectly support the simulation results with respect to the electron temperature saturation and the channel width effect on the thruster discharge.

Sandstone acidizing using mud acid is a quick and complex process where dissolution and precipitation occur simultaneously. Retarded mud acids are less reactive with the rock reducing the reaction rate hence increased penetration into the formation to remove deep damage. To understand thoroughly the retarded mud acid system, an in-depth investigation of the reaction of HF (hydrofluoric) and H2SiF6 (fluorosilic acid) with alumino silicates and the retarded system is undertaken using coreflood analysis and mineralogy analysis using the inductively coupled plasma. Coreflood analysis is used to understand and investigate the permeability changes in the sandstone rock as the retarded mud acid is injected at different conditions and the inductively coupled plasma (ICP) is used to investigate the effluent samples from the coreflood analysis to properly understand this system. Several issues that have not been addressed previously in literature are identified and discussed, including an optimum flowrate when sandstone is acidized, by acidizing the sandstone rock with a retarded acid system at various flowrates and determining the initial and final permeabilities. Also investigated is the retarded acids compatibility with ferric iron and a comparison of the retarded acid system to regular acid to consequently enable a thorough understanding of the retarded mud acid system using aluminum chloride (AlRMHF). Based on the work done, it is found that the absence of a hydrochloric (HCl) preflush is very detrimental to the sandstone core as calcium fluoride is precipitated and the retarded acid system is found to be compatible with iron(III) as an impurity. The regular acid (RMHF) dissolves considerably more silicon and produces more fines than the AlRMHF. 1cc/min is found to be the optimum flowrate when a sandstone core is acidized with AlRMHF. At this low flowrate, less silicon is dissolved, more aluminum is seen in the effluent and more calcium is dissolved. The retarded aluminum acid system considerably reduces the rate of reaction as evidenced in the dissolution reaction when compared to a regular mud acid system. This reduced rate of reaction implies deeper acid penetration and ultimately deeper damage removal.

Although inductively coupled plasma mass spectrometry (ICP-MS) is generally considered a reliable analytical technique, increasing demands on its capabilities require continued research and improvements. ICP-MS is susceptible to both matrix effects and drift, leading to a decline in accuracy and precision. A number of techniques are routinely used to compensate for these issues. Internal standardization is one such solution that requires relatively simple sample preparation and yet offers the possibility of improving both accuracy and precision. In order to be effective, an optimal analyte/internal standard pair must be chosen. Traditionally, analyte/internal standard pairs are chosen based on similarities in mass and/or ionization potential. The present studies sought to develop a program that determined standards based on the minimization of analytical error. 102 masses were monitored over 27 perturbations, i.e., changes to sample matrix and operating parameters. The standard deviations of the analyte/internal standard ratios were then used as a measure of internal standard performance. A thorough statistical analysis was conducted to determine trends between a good analyte/internal standard pair and similarities in chemical property. Similarities in mass offered the strongest relationship to a good internal standard choice, although many exceptions existed. The program was then tested over time and multiple instrument optimizations as well as on a completely different ICP-MS instrument. Results of these tests suggest that the data originally collected for the prediction program is not instrument-specific and thus provided a broader base of useful applications. Due to its unmatched sensitivity and multielement capabilities, ICP-MS is frequently utilized for biological samples. A more recent application, however, seeks to use ICPMS for the purpose of determining specific associations between metals and proteins. Such speciation requires a high resolution and reproducible separation prior to ICPMS analysis. Gel electrophoresis offers good separation and is well matched with the scanning properties of laser ablation sample introduction. The present study utilized native gel electrophoresis coupled with a uniquely modified electroblot system to improve sensitivity and to elucidate additional information. Chemically modified quartz fiber filters were successfully used as the transfer membrane to improve protein and metal capture efficiency. / text

This study is concerned with the compositional analysis of Roman and early post-Roman glass from both domestic assemblages and the remains derived from glass working and producing sites in Britain, using Inductively Coupled Plasma Spectrometry (ICPS). Samples analysed were from glassworking waste from Mancetter (midsecond century), Leicester (third century) and Worcester (first to third centuries), glass production debris, probably manufactured from the raw materials, in conjuncton with a domestic assemblage, from Coppergate (first to fourth centuries, or possibly later), and a domestic assemblage from Fishergate (spanning both the Roman and immediate post- Roman periods). All the glass analysed was shown to be of a typical and uniform soda-limesilica composition, except for a small number of vessel fragments from York which were higher in calcium. Any compositional differences between blue-green glasses typologically dated either to the Roman or Saxon periods, were found not to be consistent. Analysis of the colourless glass showed that the majority appeared to be actively decolorized using antimony, in conjunction with apparent differences in the compositions of the raw materials, when compared to glass of the same date in other colours. Compositional differences between melted waste from Mancetter, Leicester and Worcester, were apparent, but not to an extent which allowed characterization to be successful. Analysis of glassmelting pots from Coppergate showed some high temperature glassworking (and possibly glassmaking) could have occurred. Other debris, thought to be indicative of glassmaking was also analysed and compared to the composition of the Roman domestic assemblage.

[Truncated abstract] The analysis and subsequent interpretation of trace evidence is of paramount importance to the forensic scientist. While a variety of methods are available to facilitate comparison between recovered and control samples, the use of a specific analytical method depends upon both the physical and chemical nature of the material itself and the material to which it is to be compared. Elemental analysis of evidentiary material is one such method of sample comparison and has been extensively applied to this purpose following the introduction of neutron activation analysis in the early 1960s. However, over the last 15 years, another instrumental technique has taken centre stage in the analytical armoury of the forensic scientist: laser ablation–inductively coupled plasma-mass spectrometry (LA-ICP-MS). The modification and adaptation of this technique, to a point where it is possible to distinguish between glass materials produced only hours apart on the same production line, is detailed in this thesis. Additional protocols have also been developed for the analysis of fibreglass and plastic crime scene debris. Finally, a method for quantification of elemental concentrations in headlamp plastics has also been developed to facilitate inter-comparison of data between both different analytical techniques and different laboratories. Glass material is one of the most common varieties of trace evidence and the forensic examination of glass traditionally involves the determination of its refractive index (RI). ... The analytical protocol involves the analysis of 46 analytes on material comprising the exterior surface of the lens. Using this data, it was found that although minor variations in elemental composition exist within a single headlamp lens, discrimination between lenses produced from a single manufacturing plant over a short period of time could still be achieved. Discrimination between all headlamp lenses, with the exception of some lenses produced on the same day, could be facilitated using the analytical protocol developed. Furthermore, an interpretational protocol has been developed that has successfully classified all unknown headlamp lens samples investigated in this study, within the discrimination limits of the analytical method. The semi-quantitative analysis of glass and plastic samples has also been examined using LA-ICP-MS. The concentrations of 16 analytes in container and float glass samples were determined. However, the levels of discrimination afforded by the semi-quantitative data were inferior to those achieved using qualitative data. Finally, a series of plastic-based standards, containing 25 analytes of known concentrations, was produced. Using these standards, relative concentrations of the study analytes were determined in polycarbonate headlamp lenses. Interpretation of the data produced made it possible to discriminate between all study samples. Consequently, the total analytical and interpretational protocol developed in this study has established the foundation for LA-ICP-MS to be adopted internationally as a recognised method for the analysis of plastic crime scene debris.