Browsing by study line "Chemistry"

A geopolymer waste form containing gasified ion exchange resin loaded with stable analogues of radionuclides (e.g., Sr, Co, Ni, Cr, Cs) was studied using semi-dynamic batch leaching experiments. The experiments were conducted for 180 days using an alkaline groundwater simulant in a glove box with controlled N2 atmosphere with < 10 ppm CO2 and O2. The experiments were conducted to investigate the leaching behavior of the geopolymer in conditions relevant to a low- and intermediate-level waste repository. The leaching results of the geopolymers showed leaching of cesium, sodium, aluminum, and silicon from the geopolymer, while potassium and calcium in the leachant sorbed to the geopolymer. The leaching and sorption rates were at their highest for the first 28 days of the experiment, before slowing down to a steady state which were maintained until the end of the experiment. This suggests that the geopolymers immobilized the waste analogues effectively with exception of cesium which had leached by 55 wt% of the initial fraction by day 180. The leaching indices of sodium, aluminum, silicon, and cesium were determined as: 9.9 ± 0.38, 10.1 ± 0.47, 10.5 ± 0.40, and 9.1 ± 0.30 respectively. The leaching indices are well above 6, which is considered a minimum value for WAC of cementitious waste forms by USNRC. The solid phase analysis of the geopolymer samples showed both presence of calcium rich secondary phases and increasing calcium concentration in the bulk matrix on the leachant contact surface of the geopolymer. It was concluded that the secondary phases consisted of CaCO3 minerals.

The thesis gives an overview of indoor air pollution sources, health effects, and the detection of the fungal markers in indoor environment. In the experimental part of the thesis, solid phase extraction-liquid chromatography-tandem mass spectrometry method was developed for the quantitative analysis of 23 fungal secondary metabolites. The method was used to analyze the condensate water in indoor air from two sick houses in the Southern part of Finland. Furthermore, the practice was used to find other possible fungal marker compounds. The concerns of the indoor air pollution have been steadily increasing for the past couple decades since the prevalence of the irritative symptoms, such as skin, eye and respiratory track problems, that have been increasing without any clear reasoning. These symptoms are therefore being referred as building related symptoms since no other functionality have been discovered to be responsible for those. The general sources that could be linked to the cause of these symptoms are comfort parameters, material and burning related sources, and microbial metabolism products. From the microbes, the fungal species exhibit biggest concerns related to the indoor air quality since the growth of the fungus in the suitable conditions can lead to sizeable emissions of the particles and secondary metabolites which might be toxic, irritating or otherwise unhealthy. The traditional way of detecting the fungal contamination has required highly trained professional who investigates the interiors of the suspected contaminated house with the help of a moisture detector. When the contaminated spot is detected, the expert would conduct a visual inspection, and take a sample of the fungal growth for the microscopic analysis. Since then, methods focusing on the detection of the fungal particles and compounds have been developed. These include the collection of the bioaerosols and the detection of the volatile organic compounds originating from the fungal metabolism. However, there are challenges and limitations on these methods such as dependencies on time, low concentrations, and other pollution sources having similar chemical profiles than the fungal sources. Therefore, diverse ways to analyze the chemical profile of the sick houses is needed. Consequently, in the experimental part of this thesis, the method was developed to analyze fungal secondary metabolites from the condensate of the indoor air. The investigation consisted of the two fungal contaminated sick houses and from the one reference laboratory air sample. The results revealed twelve compounds to be elevated in the indoor air compared to the outdoor air and seven of these compounds were not detected in the reference sample. From these seven compounds, the studied amino acids and caffeine were the most promising fungal marker compounds since these compounds had consistently larger concentrations indoors than outdoors. Furthermore, the precursor ion scan revealed nine more potential marker compounds.

Although hot particles can be released to the environment via many pathways (nuclear accidents, warfare, industry), the understanding of their behavior in the human body, as well as their consequent health impacts. This study aims to understand how uranium particles (UO2 particles) and particles derived from nuclear accidents (Cesium-rich Micro-Particles, CsMPs) behave chemically after inhalation and how they impact human lungs. Specifically, the study aims to ascertain the duration of particle persistence within tissues post-inhalation, investigate the likelihood of translocation or chemical modifications, and evaluate both the chemical and possible radiobiological risks posed to organisms. To achieve this objective, the physicochemical alterations of UO2 particles and CsMPs after exposure to simulated lung fluids and their resulting cytotoxicity in cell models are studied. Dissolution studies are conducted, first using simulated lung fluid (SLF), that represents the interstitial lung fluid in the lung alveolar, followed by artificial lysosomal fluid (ALF), which mimics the conditions particles encounter after internalization by alveolar macrophages. Particle solubility is assessed using chemical analytical techniques (ICP-MS). Thus, the potential dissolution of these particles or their ability to persist as intact point sources of radiation over extended periods is explored. Particles after dissolution are examined using SEM-EDX analysis to study changes in the surface morphology and chemical composition. Additionally, the initial uptake and cytotoxic effects of these particles is investigated using murine lung fibroblast and macrophage cell lines, aiming to establish a detailed understanding of their radio- and chemical toxicity. UO2 particles presented minimal dissolution in SLF(< 2% of U dissolved) during 60 days of dissolution and a formation of a secondary phase on the surface of the particle was observed (mineral of uranyl associated with phosphates, most likely autunite). After exposure to ALF for 30 days, UO2 particles dissolved extensively ( ̴ 90% of U dissolved). From the single-particle dissolution for the CsMPs generated from the Fukushima-Daiichi accident, preliminary data has shown that within 30 days, a range of 10-25% of Cs-137 was leached into the SLF solution. Modified UO2 (after dissolution in SLF for 10 days, 180 days or ALF for 30 days) shown similar cell cytotoxicity profile as unmodified UO2 particles (20-40% cell viability after 24 hours).

Bioorthogonal chemistry and click chemistry have gained tremendous attention during the past few years. They do not refer to a single reaction but to a class of reactions that take inspiration from nature. Click reactions are driven by a strong thermodynamic driving force and therefore they proceed via well-controlled and consistent reaction pathways. Click reactions afford specific products in high yields with negligible by-products. Bioorthogonal chemistry builds on the boundaries set by click chemistry. Bioorthogonal reactions can occur within a living system without interacting or interfering with the natural biological processes therefore both the reactants and the products must be inert and stable under physiological conditions. Bioorthogonal reactions have allowed the real-time study of several biomolecules such as glycans, lipids, nucleic acids, and proteins within living systems without cytotoxicity. In the literature section of the thesis, the most important physical properties of both the isonitrile and chlorooxime are introduced and the most important bioorthogonal reactions for both functionalities are highlighted. The bioorthogonal isonitrile-chlorooxime ligation is discussed in more detail and an example is given of how the ligation can be used to label the cell membrane of living cells with fluorescent moieties. To install a moiety on the cell membrane it must first be modified with small non-natural chemical functionalities also called “chemical reporters.” which can be installed with metabolic oligosaccharide engineering (MOE) using monosaccharide analogues. After installation of the “chemical reporters” onto the cell surface, molecules containing the corresponding bioorthogonal counterpart can be attached to the cell membrane. Lastly, the sulfur(VI) fluoride exchange (SuFEx) click chemistry is discussed. Traditionally, SuFEx click chemistry has been used in organic chemistry to build inorganic connecting bridges between two carbon centres. More recently, SuFEx chemistry has found utility in the radiosynthesis of fluorine-18 containing [18F]sulfonyl fluorides and [18F]fluorosulfates. Fluorine-18 is one of the most commonly used and important positron emitters utilized in radiopharmaceutical chemistry and positron emission tomography (PET). The experimental section of the thesis presents the synthesis routes of the bioorthogonal reaction partners, a peracetylated isonitrilepropanoylmannosamine (Ac4ManNC) and an aryl fluorosulfate chlorooxime. The research hypothesis of the study was that the isonitrile of the Ac4ManNC could be installed onto the cell surface of living Jurkat cells (human T lymphoblast) with MOE. Afterwards, the fluorine-18 labelled aryl [18F]fluorosulfate chlorooxime could have been attached to the cell surface from the isonitrile with the bioorthogonal isonitrile-chlorooxime ligation. This cell surface labelling method could have then been used in the future to research and develop cell therapy treatments by utilizing PET imaging.

Kultakomplekseille on tyypillistä typpi- ja rikkidonoreita sisältävät ligandit. Suurin osa tunnetuista kultakomplekseista on homoleptisiä, eli niissä kulta on liittynyt vain yhdentyyppisiin ligandeihin. Heteroleptisissä komplekseissa keskusatomiin on liittynyt useammanlaisia ligandeja. Heteroleptiset kompleksit ovat kiinnostavia, sillä kompleksien rakenteen muutokset vaikuttavat mm. katalyyttien tehokkuuteen. Kahden erilaisen ligandin avulla voidaan esimerkiksi vaikuttaa keskusatomin koordinaatiokykyyn merkittävästi. Kirjallisuuskatsauksessa tarkastellaan kullan komplekseja ja erilaisten ligandien käyttäytymistä kullan kanssa. Kirjallisuudesta löytyneiden heteroleptisten kultakompleksien ominaisuuksia, synteesireittejä ja käyttökohteita on esitelty. Kirjallisuudesta on etsitty esimerkkejä heteroleptisistä kultakomplekseista sekä kultatiolaattien reaktioista. Kokeellisessa osuudessa tutkittiin kullan liuotusreaktiota sekä pyrittiin valmistamaan ja analysoimaan heteroleptistä kultatiolaattia, jollaisia ei kirjallisuuskatsauksen perusteella ole valmistettu. Kullan liuotusreaktiossa, jossa hyödynnetään kahta eri tiolaattiligandia, on havaittu muodustuvan välituotteena heteroleptinen tiolaattikompleksi, jonka tarkempi karakterisointi oli työn tavoitteena. Vaikka valitulla synteesistrategialla kompleksia ei saatu eristettyä puhtaana, sen muodostuminen varmistui mm. massaspektroskopian avulla.

In the literature part, different analytical techniques for investigating drug-lipid interactions were reviewed, with the emphasis being on capillary electromigration and liquid chromatog-raphy techniques involving the use of artificial lipid vesicles called liposomes. Special interest was reserved for studies on beta blockers, a class of cardiovascular drugs. In addition, com-mercial intravenous lipid emulsions were introduced and in vivo and in vitro research on them was reviewed, mainly focusing on studies of their application in treatment of drug over-doses. Other methods for studying drug-lipid interactions were also briefly discussed and compared to electrophoretic and chromatographic techniques. In the experimental part, the interactions of seven beta blockers with a commercial intrave-nous lipid emulsion, Intralipid, were studied by a capillary electrophoresis technique called liposome electrokinetic chromatography. Electrophoretic mobilities of the analytes in a capil-lary filled with Intralipid solution were determined. From the mobilities of the analytes and Intralipid solution, retention factors and distribution coefficients for the beta blockers were determined. The values were compared with literature octanol/water partition coefficients and experimentally determined partition coefficients from previous research. The particle sizes of the lipid emulsion were studied by dynamic light scattering and flow field-flow fractionation. Other capillary electromigration techniques such as partial-filling electrokinetic chromatog-raphy and capillary electrophoresis frontal analysis were also briefly performed, and the results were compared with liposome electrokinetic chromatography. Also, interactions of the In-tralipid solution with the silica capillary wall were studied.

The relentless demand for diverse aromatic scaffolds, essential in fields ranging from material science to pharmaceuticals and agrochemicals, has driven the development of efficient aromatization reactions. The 20th century saw significant advancements in transition metal (TM) catalysis, leading to numerous metal-catalyzed systems for converting non-aromatic precursors into aromatic compounds. However, current research is increasingly guided by sustainability and green chemistry principles. This review provides a historical context for aromatization reactions and presents a comprehensive overview of metal-free methods, with a particular emphasis on the aromatization of carbocycles. The potential of these metal-free approaches to offer greener, more economically feasible alternatives to traditional methods is critically evaluated.

Black carbon is an aerosol that is a product of incomplete combustion, the main sources are anthropogenic, such as internal combustion engines and burning of biomass. It is ideally absorbing across the visible light spectrum. Carbonaceous aerosols have a range of negative effects such as lung diseases in the local population and radiative force on the Earth. Therefore it is important to determine not only the concentration of these aerosol particles but also identify their sources. Typical measurement methods for monitoring of aerosols involves instruments employing a filter based technique such as an aethalometer. The major drawbacks to such instruments are that the time resolution is in the order of some minutes and some form of correction factors must be applied depending variations such as the time of year the measurement and differing compositions of carbonaceous aerosols based on locality. A 3 wavelength cantilever enhanced photoacoustic spectroscopy instrument was developed during this work to detect the absorption of these particles across the visible range. The benefits of using cantilever enhanced photoacoustic spectroscopy are a time resolution in the order of seconds rather than minutes and that no correction factor is required for the measured absorption value for the particles. In this thesis it is demonstrated that multi-wavelength photoacoustic spectroscopy can be used for measuring black carbon aerosols and the information obtained can be used estimate the source of those particles.

Oxidized compounds in the atmosphere can occur as emitted primary compounds or as the products of secondary formation when volatile emitted precursors react with various oxidants. Due to the polar functional groups, their vapor pressures decrease and they condense onto growing small particles or forming new particles by the cloud condensation nuclei reaction. Small particles affect climate change by the formation of clouds and scattering solar radiation. The particles and oxidized compounds themselves could cause serious health problems when inhaled. Thereby, the study of oxidized compounds in the atmosphere is very important. Based on the literature review, the focus of the research is to discover new oxidized species, and to evaluate their sources and factors affecting their formation. Monitoring of biogenic and anthropogenic primary oxidized compounds or secondarily oxidized products in chamber experiments or field campaigns is common. New discoveries have been reported including various new oxidized compounds and a new group of compounds called highly oxidized organic molecules (HOMs). Analytics is mainly focused on chromatographic methods identifying and quantifying compounds in low concentrations. The analytics of HOMs are currently based on high-resolution mass spectrometry employing chemical ionization. Oxidized compounds could also be monitored by spectrophotometric methods in which the determinations of total amounts are based on functional groups. In the experimental part of this thesis, a liquid chromatography-tandem mass spectrometric method applying hydrophilic interaction chromatography was developed to analyze 18 organic acids. The developed method was sensitive to C4-C10 dicarboxylic acids and aromatic acids. In contrast, for smaller and multifunctional acids, the sensitivity decreased due to broader chromatographic peaks. Acids were determined from aerosol samples which were collected with conventional filter sampling and miniaturized filter sampling on a drone. The aim of the work was to compare samples collected with two different sampling techniques to assess if they provided comparable results. Concentration differences between daytime and night-time was assessed from samples taken with conventional filter sampling. C4-C9 dicarboxylic acids, cis-pinonic acid, benzoic acid, phthalic acid, and glycolic acid were detected in both sample types. Possible elimination of adsorption from gas phase to particle phase was demonstrated for cis-pinonic acid and succinic acid due to the lower sample volume in drone sampling. Other detected acids’ concentrations were comparable between two different sampling strategies, considering different sampling sites and extraction methods. Daytime and night-time comparison suggest that acids’ concentrations are higher in daytime when photo-oxidation reactions occur.

Piperine represents the major plant alkaloid encountered in various Piperaceae species and has received in recent years considerable attention because of its broad range of favorable biological and pharmacological activities, including antioxidant, immunostimulant, bioavailability-enhancing and anti-carcinogenic properties. The literature part of this thesis gives a selective overview of advanced methods for the quantitative analysis of piperine in plant-base materials, and various approaches employed for instrumental analysis, including spectroscopic, chromatographic, and electrochemical techniques. An effort was made to evaluate the potential of the reported methods based on the analytical figures of merit, such as total sample throughput capacity, analytical range, precision, accuracy, limit of detection and limit of quantification. The objective of the experimental part of the thesis focused on the development of a convenient, robust, simple, efficient and reliable method to quantify piperine in pepper fruits. The analytical method established in this thesis involves liberation of piperine by continuous liquid extraction of ground pepper fruits with methanol, and cleanup of the crude extracts with reversed phase solid phase extraction. Analyte quantitation was accomplished using gradient reversed phase High Performance Liquid Chromatography with mass spectrometric detection, using Electrospray Ionization-Ion Trap Mass Spectrometry. To enable reliable internal standardization, deuterium labelled piperine surrogate (piperine-D10) was synthesized from piperine in three steps in a reasonable overall yield (65 %) and standard-level purity (99.7 %). It may be worth mentioning that the commercial market value of the amount of piperine-D10 synthesized in-house exceeds 167,400 euros. One of the major challenges encountered during the development and optimization of the analytical method was the extreme photosensitivity of piperine and piperine-D10, both suffering in solution extensive photoisomerization upon exposure to ambient light within matter of minutes. This issue was addressed by carrying out all tasks associated with synthesis, sample preparation and analytical measurements under dark conditions. For the preparation of calibrators, a fully automated procedure was developed, being controlled by custom-written injector programs and executed in the light-protected sample compartment of a conventional autosampler module. In terms of merits, the developed analytical method offers good sample throughput capacity (run time 20 min, retention time 8.2 min), excellent selectivity and high sensitivity (Limit of Detection= 0.012 ppm, Limit of Quantification= 0.2 ppm). The method is applicable over a linear range of 0.4 to 20 ng of injected mass (r2= 0.999). The stability of standards and fully processed samples was found to be excellent, with less than 5% of variations in concentrations occurring after a 3-week (calibrators) or 4-month (samples) storage at 4 °C and 23 °C respectively, under dark conditions. Intra-day repeatability were better than 2.95 %. Preliminary validation data also suggest satisfactory inter-operator reproducibility. To test the applicability of the developed LC-MS method, it was employed to quantify piperine in a set of 15 pepper fruit samples, including black, white, red and green varieties of round and long peppers, purchased from local markets and retailers. The piperine contents obtained were in the range of 17.28 to 56.25 mg/g (piperine/minced sample) and generally in good agreement with the values reported in the scientific literature. It is justified to assume that the developed analytical method may directly be applicable to the quantitation of related pepper alkaloids in herbal commodities, and after some modifications in the sample preparation strategy, also for the monitoring of piperine in biological fluids, such as serum and urine.