Kinetic data is presented for a variety of ion-neutral reactions which are relevant to the atmosphere of Titan and to the chemistry occurring in interstellar clouds. The data were recorded with a Selected Ion Flow Tube (SIFT) operating at room temperature (294 ± 4 K) and at a pressure of 0.46 Torr. Results of the recent Cassini-Huygens mission to Saturn and Titan have identified several species in the atmosphere of Titan not predicted by pre-Cassini models of the atmosphere. In order to determine the fate of three of these species (methylenimine, propionitrile and cyanodiacetylene) in Titan's ionosphere, their reactivity with the principal ions in Titan's upper ionosphere has been examined. As expected, collision rate proton transfer reactions dominate the chemistry with association channels also observed with many of the hydrocarbon ions. The results of the Cassini mission also identified several individual reactions as being of potential importance to models of Titan's atmosphere and this chemistry has also been examined. The above studies are also relevant to the interstellar medium where each of the neutral reactants have also been detected. The results of some proton transfer equilibrium studies are also presented. The gas phase basicities of propyne and acetylene have been determined to be 681 kJ mol⁻¹ and 617.4 kJ mol⁻¹ respectively. Their relative proton affinities can be estimated from these values. A combined experimental/theoretical study of the proton affinity of cyanodiacetylene (HC₅N) has enabled this value to be estimated at 770 ± 20 kJ mol⁻¹. Details of an attempt to complete the first laboratory measurement of the crucial reaction between H₃⁺ and atomic carbon are presented. The generation of atomic carbon in sufficient quantities for reaction in the SIFT was not possible with the microwave discharge source used. Other generation methods have also been explored with the laser photolysis of carbon suboxide expected to provide a possible solution to the problems encountered. The results of an investigation into the applicability of lithium ions (Li⁺) to SIFT-MS are presented. The lithium ions associated with each of the twenty-one neutral analytes examined to form pseudo-molecular ions. The association reactions were rapid (k ~ 10⁻⁹ cm³ s⁻¹) for large hydrocarbons but were much slower for smaller analytes (k < 10⁻¹¹ cm³ s⁻¹). In order to clarify some unusual experimental observations, the effect of water molecules on the observed chemistry has been examined in detail. The measured chemistry has important consequences for the applicability of Li⁺ to SIFT-MS where the presence and detection of an identifiable ion of the analyte is essential. Details of new SIFT operating software which can be run on a modern computer are given. Mass spectra and kinetic data recorded with the new software are also presented.

Kinetic data is presented for a variety of ion-neutral reactions which are relevant to the atmosphere of Titan and to the chemistry occurring in interstellar clouds. The data were recorded with a Selected Ion Flow Tube (SIFT) operating at room temperature (294 ± 4 K) and at a pressure of 0.46 Torr. Results of the recent Cassini-Huygens mission to Saturn and Titan have identified several species in the atmosphere of Titan not predicted by pre-Cassini models of the atmosphere. In order to determine the fate of three of these species (methylenimine, propionitrile and cyanodiacetylene) in Titan's ionosphere, their reactivity with the principal ions in Titan's upper ionosphere has been examined. As expected, collision rate proton transfer reactions dominate the chemistry with association channels also observed with many of the hydrocarbon ions. The results of the Cassini mission also identified several individual reactions as being of potential importance to models of Titan's atmosphere and this chemistry has also been examined. The above studies are also relevant to the interstellar medium where each of the neutral reactants have also been detected. The results of some proton transfer equilibrium studies are also presented. The gas phase basicities of propyne and acetylene have been determined to be 681 kJ mol⁻¹ and 617.4 kJ mol⁻¹ respectively. Their relative proton affinities can be estimated from these values. A combined experimental/theoretical study of the proton affinity of cyanodiacetylene (HC₅N) has enabled this value to be estimated at 770 ± 20 kJ mol⁻¹. Details of an attempt to complete the first laboratory measurement of the crucial reaction between H₃⁺ and atomic carbon are presented. The generation of atomic carbon in sufficient quantities for reaction in the SIFT was not possible with the microwave discharge source used. Other generation methods have also been explored with the laser photolysis of carbon suboxide expected to provide a possible solution to the problems encountered. The results of an investigation into the applicability of lithium ions (Li⁺) to SIFT-MS are presented. The lithium ions associated with each of the twenty-one neutral analytes examined to form pseudo-molecular ions. The association reactions were rapid (k ~ 10⁻⁹ cm³ s⁻¹) for large hydrocarbons but were much slower for smaller analytes (k < 10⁻¹¹ cm³ s⁻¹). In order to clarify some unusual experimental observations, the effect of water molecules on the observed chemistry has been examined in detail. The measured chemistry has important consequences for the applicability of Li⁺ to SIFT-MS where the presence and detection of an identifiable ion of the analyte is essential. Details of new SIFT operating software which can be run on a modern computer are given. Mass spectra and kinetic data recorded with the new software are also presented.

Oxygenated volatile organic compounds ((O)VOCs) contribute to ozone formation, affect the oxidising capacity of the troposphere and are sources of growth, and in some cases formation, of aerosols. It is therefore important to identify and quantify sources of (O)VOCs in the troposphere. In the late 1990s a unique technique for quantification of organic trace gas species, proton transfer reaction mass spectrometry (PTR-MS) was developed. PTR-MS potentially offers rapid response and high sensitivity without the need for sample pre-concentration. Concentrations can be derived from the PTR-MS either by calibration or can be calculated from measured ion count rates and kinetic considerations. In this work, the methodology of PTR-MS application is critically assessed. The uncertainties and inaccuracies associated with each parameter employed in the calculation of concentrations are reviewed. This includes a critical appraisal of models for the calculation of the collisional rate constant currently applied in the field of PTR-MS. The use of a model to account for the effects of the electric field, available in the literature but not previously applied to the PTR-MS, is advocated. Collisional rate constants employing each of the models discussed have been calculated for the reactions of H3O+ with over 400 molecules for PTR-MS. In PTR-MS it cannot be assumed that the product ion occurs only at the protonated non-dissociated mass. Few product distributions obtained from PTR-MS are cited in the literature, and even then the reaction chamber conditions (pressure, temperature and electric field strength) are not always specified. A large volume of product distributions for trace gases with H3O+ in select ion flow tube mass spectrometry (SIFT) exists in the literature and is reviewed. In SIFT, no electric field is applied to the reaction chamber and the extent and even nature of fragmentation can differ in PTR-MS. In addition to the application of an electric field, the energy in the reaction chamber can be increased by increasing the temperature or by variation of the reagent ion. In this work, the increase in energy via the three methods is approximated to enable a comparison of product distributions. The review of product distributions in PTR-MS, select ion flow drift tube mass spectrometry (SIFDT), variable temperature select ion flow tube mass spectrometry (VT-SIFT), SIFT, proton transfer reaction time of flight mass spectrometry (PTR-TOF-MS), proton transfer reaction ion trap mass spectrometry (PTR-ITMS) and electron ionisation mass spectrometry (EI-MS) is used alongside thermodynamic considerations to collate a list of potential contributors to a range of mass to charge ratios (m/z) in the PTR-MS. The need for further measurements of product distributions as a function of temperature, pressure and electric field strength for a wider range of (O)VOCs is highlighted. This enables dissociation to be better used as a tool for compound identification rather than being considered a hindrance. The collation of likely product distributions is applied to identify possible contributors to m/z observed during PTR-MS measurements of emission from cattle slurry. Field measurements were made during fertilisation of a grassland site south of Edinburgh in 2004 and 2005 and in laboratory-based measurements in 2006. Contextual reasoning, previous measurements and isotope ratios are used to narrow the list of possible contributors. Large concentrations of m/z cautiously identified as alcohols followed by a latter peak in carboxylic acids were observed during laboratory measurements. Increases in the corresponding m/z were also observed during the fertilisations. Other tentatively identified compounds emitted included phenol, methyl phenol, trimethylamine, and various sulphur containing compounds.

The application of Selected Ion Flow Tube Mass Spectrometry (SIFT MS) to the analysis of olive oil shows several distinct advantages over more conventional analysis techniques. The two areas described in this thesis examining olive oil quality are the analysis of Volatile Organic Compounds (VOCs) and the assessment of antioxidant activity. VOCs are responsible for the aroma and much of the taste of olive oil, while antioxidants afford some protection from harmful reactions involving radical species inside the body by scavenging radicals when olive oil is ingested. The VOCs of olive oil are used by sensory panel judges to classify oils by their degree of suitability for human consumption. The major parameters used for this evaluation are the strengths of any defects and the degree of fruitiness. A defect is an indication of an undesired process which has occurred in the oil, while fruitiness is a fragile attribute which denotes a good quality oil and is easily masked by defects. SIFT MS was used to measure the strengths of the olive oil defects rancid, winey, musty, fusty and muddy. Great potential was demonstrated for all defects except musty and the concentrations of VOCs in olive oil head space were correlated with the peroxide value, a measure of the degree of oil oxidation. A study aimed at correlating the strength of the fruitiness attribute as determined by a sensory panel with the concentrations of VOCs in olive oil head space was unsuccessful. The SIFT MS Total Oxyradical Scavenging Capacity (TOSC) assay was used to measure olive oil antioxidants. This assay measures all antioxidants in oil, not only those removed by extraction with a solvent, as it is conducted in an emulsion. SIFT MS TOSC assay results were found to correlate well with those of the widely used Folin Ciocalteu assay and the total concentration of phenolic compounds present in olive oil. Discrepancies between the two assays were most likely due to hydrophobic antioxidants which are measured by the SIFT MS TOSC assay but not the other tests.

Data is presented for a range of experiments that have been performed using a selected ion flow tube (SIFT) instrument operated at room temperature (~ 298K) with carrier gas pressures typically in the range of 0.3 – 0.6 Torr. The majority of the experiments discussed are performed on a Voice100 instrument that has not been described in detail previously. The Voice100 is a novel instrument that has been designed particularly for quantitative trace gas analysis using the SIFT-MS technique. A mixture of helium and argon carrier gases are employed in the Voice100 flow tube. By mixing carrier gases, the flow dynamics and diffusion characteristics of a flow tube are altered when compared to classic single carrier gas models. Therefore firstly, optimal flow conditions for the operation of a Voice100 are characterised. The diffusion of an ion in a mixture of carrier gases is then characterised using theoretical models and experimental techniques. This research requires that a new parameter Mp be defined regarding the mass discrimination of an ion in the non-field-free region near the downstream ion sampling orifice. Furthermore, a new method is described for the simultaneous measurement of rate coefficients for the reactions of H₃O⁺.(H₂O)n (n = 1, 2, 3) ions with analytes. Rate coefficients and branching ratios for the reactions of SIFT-MS precursor ions with specific analytes related to four individual applications are presented. For each application, the kinetic parameters are determined so as to facilitate the quantitative detection of the analytes relevant to that application. The GeoVOC application involves the measurement of hydrocarbon concentrations in the headspace of soil and water across a range of humidities. Alkyl esters are investigated to allow for the quantitative detection of each compound in fruits and vegetables. Chemical warfare agents, their surrogates and precursor compounds are studied which allows for the quantitative or semi-quantitative detection of a range of highly toxic compounds. Finally, 17 compounds classified by the US-EPA as hazardous air pollutants are studied that enables SIFT-MS instruments to replicate sections of the TO-14A and TO-15 methods.

The application of Selected Ion Flow Tube Mass Spectrometry (SIFT MS) to the analysis of olive oil shows several distinct advantages over more conventional analysis techniques. The two areas described in this thesis examining olive oil quality are the analysis of Volatile Organic Compounds (VOCs) and the assessment of antioxidant activity. VOCs are responsible for the aroma and much of the taste of olive oil, while antioxidants afford some protection from harmful reactions involving radical species inside the body by scavenging radicals when olive oil is ingested. The VOCs of olive oil are used by sensory panel judges to classify oils by their degree of suitability for human consumption. The major parameters used for this evaluation are the strengths of any defects and the degree of fruitiness. A defect is an indication of an undesired process which has occurred in the oil, while fruitiness is a fragile attribute which denotes a good quality oil and is easily masked by defects. SIFT MS was used to measure the strengths of the olive oil defects rancid, winey, musty, fusty and muddy. Great potential was demonstrated for all defects except musty and the concentrations of VOCs in olive oil head space were correlated with the peroxide value, a measure of the degree of oil oxidation. A study aimed at correlating the strength of the fruitiness attribute as determined by a sensory panel with the concentrations of VOCs in olive oil head space was unsuccessful. The SIFT MS Total Oxyradical Scavenging Capacity (TOSC) assay was used to measure olive oil antioxidants. This assay measures all antioxidants in oil, not only those removed by extraction with a solvent, as it is conducted in an emulsion. SIFT MS TOSC assay results were found to correlate well with those of the widely used Folin Ciocalteu assay and the total concentration of phenolic compounds present in olive oil. Discrepancies between the two assays were most likely due to hydrophobic antioxidants which are measured by the SIFT MS TOSC assay but not the other tests.

Data is presented for a range of experiments that have been performed using a selected ion flow tube (SIFT) instrument operated at room temperature (~ 298K) with carrier gas pressures typically in the range of 0.3 – 0.6 Torr. The majority of the experiments discussed are performed on a Voice100 instrument that has not been described in detail previously. The Voice100 is a novel instrument that has been designed particularly for quantitative trace gas analysis using the SIFT-MS technique. A mixture of helium and argon carrier gases are employed in the Voice100 flow tube. By mixing carrier gases, the flow dynamics and diffusion characteristics of a flow tube are altered when compared to classic single carrier gas models. Therefore firstly, optimal flow conditions for the operation of a Voice100 are characterised. The diffusion of an ion in a mixture of carrier gases is then characterised using theoretical models and experimental techniques. This research requires that a new parameter Mp be defined regarding the mass discrimination of an ion in the non-field-free region near the downstream ion sampling orifice. Furthermore, a new method is described for the simultaneous measurement of rate coefficients for the reactions of H₃O⁺.(H₂O)n (n = 1, 2, 3) ions with analytes. Rate coefficients and branching ratios for the reactions of SIFT-MS precursor ions with specific analytes related to four individual applications are presented. For each application, the kinetic parameters are determined so as to facilitate the quantitative detection of the analytes relevant to that application. The GeoVOC application involves the measurement of hydrocarbon concentrations in the headspace of soil and water across a range of humidities. Alkyl esters are investigated to allow for the quantitative detection of each compound in fruits and vegetables. Chemical warfare agents, their surrogates and precursor compounds are studied which allows for the quantitative or semi-quantitative detection of a range of highly toxic compounds. Finally, 17 compounds classified by the US-EPA as hazardous air pollutants are studied that enables SIFT-MS instruments to replicate sections of the TO-14A and TO-15 methods.

L’objectif de ce travail était de contribuer à une meilleure compréhension du devenir atmosphérique des Composés Organiques Volatils d’origine Biogénique (COVB), émis par la végétation. La dégradation d’une série de COVB (myrcène, ocimène, a-farnesène, linalool, 6-méthyl-5-heptène-2-ol et 3-méthyl-1-pentène-3-ol), par les oxydants atmosphériques (OH, O3 et NO2), a été étudiée en utilisant différentes installations expérimentales (chambres de simulation atmosphérique et réacteur à écoulement à aérosol). Les paramètres cinétiques et mécanistiques qui ont été obtenus pour l’ensemble des réactions étudiées ont permis d’estimer les durées de vie atmosphérique des COVB (de quelques minutes à quelques heures). Des produits d’oxydation ont été identifiés et quantifiés, mais le bilan total en carbone en fin de réaction reste incomplet indiquant que d’autres produits sont formés mais non-identifiés. Les rendements de formation des aérosols organiques secondaires (AOS) ont été également mesurés pour les réactions avec OH et O3. L’analyse chimique des AOS (issus de la réaction avec O3) a mis en évidence la présence d’acides dicarboxyliques et de composés oligomères, démontrant l’implication des intermédiaires de Criegee dans la formation des AOS. Le réacteur à écoulement à aérosols, développé dans le cadre de ce travail, a permis de préciser les seuils de nucléation des AOS formés à partir de l’ozonolyse de certains monoterpènes. Enfin, la réactivité des COVB (principalement les diènes conjugués) avec NO2, a été trouvée assez lente et ne représente qu’un puits mineur de ces composés dans l’atmosphère. Toutefois, la mise en évidence de la formation de HONO comme produit de réaction pourrait rendre l’implication atmosphérique de ce processus non négligeable. Les résultats obtenus ont permis de discuter de l’impact de la dégradation de ces COVB dans l’atmosphère. / The aim of this work was to contribute to a better understanding of the atmospheric fate of Biogenic Volatil Organic Compounds, emitted by vegetation. The degradation of a series of BVOC (myrcene, ocimene, a-farnesene, linalool, 6-methyl-5-heptene-2-ol and 3-methyl-1-pentene-3-ol) through reactions with atmospheric oxidants (OH, O3 and NO2) has been investigated using different experimental facilities (atmospheric simulation chambers and aerosol flow tube). First, atmospheric lifetimes of these BVOCs were determined and found varying from few minutes to hours. In addition, gas phase oxidation products were identified and quantified. However carbon budget is still incomplete, indicating that others products are formed but remain unidentified. Secondary organic aerosol yield were also measured in the reactions of the studied BVOCs with OH and O3. Chemical analysis of SOA (from O3 reaction) showed the presence of dicarboxylic acids and oligomer compounds, indicating the possible involvement of the Criegee intermediate in the SOA formation. The new aerosol flow tube, developed in this work, allowed to precise nucleation threshold of SOA formed from the ozonolysis of series of monoterpenes. The reactivity of BVOC (conjugated dienes mainly) with NO2, is found to be slow process, hence, representing only a minor sink for these compounds in the atmosphere. However, the identification of HONO as a reaction product may indicate that this process could be of importance as OH radical source in the atmosphere under certain conditions. The results obtained allowed to discuss the impact of the degradation of these BVOC in the atmosphere.

<div> <p>Guided by the continuous manufacturing paradigm shift in the pharmaceutical industry, the proposed thesis focuses on the implementation of an integrated continuous crystallization platform, the oscillatory baffled crystallizer (OBC), with real time process monitoring. First, by defining an appropriate operating regime with residence time distribution (RTD) measurements, a system can be defined that allows for plug flow operation while also maintaining solid suspension in a two-phase system. The aim of modern crystallization processes, narrow crystal size distributions (CSDs), is a direct result of narrow RTDs. Using a USB microscope camera and principal component analysis (PCA) in pulse tracer experiments, a novel non-contact RTD measurement method was developed using methylene blue. After defining an operating region, this work focuses on a specific process intensification technique, namely spherical crystallization.</p> <p>Used mainly to tailor the size of a final dosage form, spherical crystallization removes the need for downstream size-control based unit operations (grinding, milling, and granulation), while maintaining drug efficacy by tailoring the size of the primary crystals in the agglomerate. The approach for generating spherical agglomerates is evaluated for both small and large molecules, as there are major distinctions in process kinetics and mechanisms. To monitor the spherical agglomeration process, a variety of Process Analytical Technology (PAT) tools were used and the data was implemented for scale-up applications.</p> <p>Lastly, a compartmental model was designed based on the experimental RTD data with the intention of predicting OBC mixing and scale-up dynamics. Together, with validation from both the DN6 and DN15 systems, a scale independent equation was developed to predict system dispersion at different mixing conditions. Although it accurately predicts the behavior of these two OBC systems, additional OBC systems of different scale, but similar geometry should be tested for validation purposes.</p> </div> <br>

This dissertation thesis summarizes results of experiments that have been carried out during my PhD studies related to the new mass spectrometric methods for trace gas analysis of human breath. The thesis is divided into the theoretical and experimental part. The chapter at the beginning of this dissertation summarizes the current research in the area of breath analysis. It is describing the common breath metabolites, benefits and challenges of the method for therapeutic monitoring and clinical diagnosis and current applications. The next chapter of the theoretical introduction describes the techniques suitable for this area of research, with a special emphasis on mass-spectrometric techniques (in particular the selected ion flow tube mass spectrometry, SIFT-MS, method that allows accurate quantification of trace gases and vapours in humid air/human breath). All these parts are elaborated via the scientific literature review. The following chapters are then directly related to my own research and describes the conducted experiment, including the results obtained. This experimental part "Results and Discussion" is divided to the individual subsections, which are conceived as the commentaries to the enclosed research papers published in peer reviewed journals. The first is the detailed step by step...