Browsing by study line "Kemia"
Now showing items 21-40 of 56
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(2023)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.
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(2024)The processing of nuclear waste to reduce its volume and radiotoxicity is an important step before it can be safely disposed of. Partitioning and transmutation refer to the concept of separating elements from nuclear waste and converting one element into another through nuclear reactions. For the transmutation of nuclear waste, it is crucial to separate the waste into different groups, particularly lanthanides from actinides, because in transmutation the high neutron capture cross-section of lanthanides can cause neutron poisoning of nuclear reactors. Separation of nuclear waste has previously been carried out by solvent extraction, but this study focuses on solid-phase extraction, which is simpler and more environmentally friendly. In this study, the submicron ZrO2 fibers were produced by the electroblowing method. The fibers were chosen over the particles in this work based on the fibers’ ability to perform better in flow-through separation columns and their faster adsorption kinetics. Prepared fibers were calcined at different temperatures and then characterised using XRD, SEM, CHN-analysis, IR, TGA, and BET surface area analysis. Fibers were further functionalised with a phosphonic acid ligand ATMP to improve their separation capability. Hybrid fibers were characterised by SEM, CHN-analysis, IR, TGA, and EDS to see the success of ligand attachment by comparing them to metal oxide fibers alone. Hybrid fibers worked well as ion exchangers. Their ion exchange capability and selectivity were tested with 241Am and 152Eu nuclides. Tests were done at different pH levels, calcination temperatures, and NaNO3 concentrations. Pure zirconia fibers showed ion exchange properties above pH 5 while surface-grafted hybrid fibers worked still at pH 2 with a sorption percentage of ~100 %. All samples preferred europium, but the highest separation factor was rather modest 2.2.
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(2022)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.
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(2023)Radiocesiumin erotusmateriaaleille on jatkuvaa kysyntää maailmanlaajuisesti ydinjätteen käsittelyyn ja ympäristön dekontaminointiin liittyen. Tämän takia tarvitaan edelleen lisää tutkimusta tehokkaampien ja selektiivisempien cesiumadsorbenttien kehittämiseksi. Lisäksi näiden adsorbenttien regenerointitapojen kehittäminen on oleellinen tapa vähentää muodostuvan kiinteän radioaktiivisen jätteen määrää. Metalliheksasyanoferraatit ovat paljon käytettyjä ja tutkittuja materiaaleja cesiumin erotukseen ja yhdistettynä sähköisesti ohjattuun ioninvaihtoon niistä voidaan valmistaa tehokkaita, selektiivisiä, kestäviä ja uudelleenkäytettäviä ioninvaihtimia. Työn tavoitteena oli valmistaa tällainen sähköllä regeneroitava ja selektiivinen grafeeniaerogeelistä ja heksasyanoferraatista koostuva komposiitti-ioninvaihdin cesiumin erotukseen. Työn kokeellisessa osassa valmistettiin onnistuneesti erilaisia kylmäkuivattuja aerogeelejä eli kryogeelejä, joiden korkea hapettuneisuus teki niistä joustavia ja kestäviä ilmassa. Toisaalta vastaavat askorbiinihapolla pelkistetyt kryogeelit olivat kovia ja soveltuivat mekaanisilta ominaisuuksiltaan paremmin käytettäväksi adsorbenttina vesiliuoksissa. Yksi merkittävimmistä havainnoista oli sentrifugoinnin tärkeys grafeenioksidisuspension homogenisoinnin kannalta, jotta saatiin valmistettua yhtenäinen tuote. Valmistettujen grafeenikryogeelien ja indiumtinaoksidin pinnalle saostettiin nikkeliheksasyanoferraattia, jonka hapettumis-pelkistymisreaktioita mitattiin onnistuneesti syklisellä voltammetrialla. Näiden komposiitti-ioninvaihtimien avulla radiocesium voitiin erottaa vesiliuoksesta lähes kvantitatiivisesti, mutta kiinnittyneestä cesiumista saatiin eluoitua tämän jälkeen jännitteen avulla vain noin 10 %. Tuotteita karakterisoitiin myös jauheröntgendiffraktiolla ja energiadispersiivisellä röntgenspektroskopialla.
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(2024)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).
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(2022)In chemical forensics inorganic analysis is for example used to detect traces of explosives and drugs, to find residues of firearms, and as aid when searching for hidden burial sites. Forensic investigators also utilise inorganic information in chemical source attribution or fingerprinting, which seeks to identify chemical profiles of inorganic and/or organic compounds and elements that can provide information on the origin of the sample, how it has been produced and using which raw-materials. As the chemical profiles typically contain information for several compounds, comparison of profiles have to be analysed by multivariate statistical tools such as principal component analysis (PCA), hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA). In this work the applicability of inorganic source fingerprinting on soil samples was investigated. For this an extraction procedure and an ion chromatographic (IC) method for the determination of F–, Cl–, Br–, NO3–, PO43–, SO42– and AsO43– in soil were developed and validated. Extraction of anions was done by microwave assisted solvent extraction, with good recoveries (86.15 % – 115.23 %) for nearly all recovery samples. The recovery of F– from soil was 174.77 %, due to enhanced extraction efficiency caused by the high extraction temperature. AsO43– could not be quantified due to low extractability and interfering matrix components. Development of a method for elemental analysis of soil samples by inductively coupled plasma mass spectrometry (ICP-MS) was also attempted. Complete dissolution was not achieved with microwave assisted acid digestion mainly because of the large particle size of the soils analysed. Samples were analysed for As, Co, Cr, Cu, Fe, Mn, Mo, Ni, V and Zn, but Ni could not be quantified from any of the samples because of the high detection limit caused by contamination of samples. Due to contamination and incomplete dissolution the variation in the results were large, leading to a large uncertainty for the results. Analysis of variance (ANOVA) revealed that there is a significant (α = 0.05) difference in the concentrations of all analytes but Mo and V between the samples. Two step PCA and LDA were performed on tha anion and elemental results separately. Better clustering of sample results were typically got with LDA than with PCA. LDA on the anion results was able to discriminate all samples while only four out of seven samples were identified by PCA. The large variation in the data meant that only the reference soil could be identified when all elemental concentrations were included. Removal of outliers from the data lead to identification of all samples by both PCA and LDA. This work showed that samples can be identified by their inorganic profiles, but large variations in the measured concentrations will make the discrimination by multivariate statistics difficult. Further work should focus on improving the separation of the IC method and on decreasing the variation in the data by decreasing sample heterogeneity and contamination during the sample preparation.
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(2023)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.
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(2022)Amidien ja esterien tehokas valmistaminen neutraaleissa olosuhteissa vaatii kytkentäreagenssien tai aktivaattoriyhdisteiden käyttämistä. Niistä jää tuotteisiin kuitenkin epäpuhtauksia, joiden poistaminen vaatii usein työlään kromatografisen puhdistusvaiheen. Tutkielmassa tarkastellaan kiintokantajareagenssien käyttöä karboksyylihappojen dehydrokondensaatioreaktioissa. Kantajareagenssit toimivat kytkentä- ja/tai aktivaattorireagensseina ja tehostavat reaktioita liuosfaasisynteesiin nähden monin tavoin. Mikäli tuote tai intermediaatti pysyy sidottuna kiintokantajaan, voidaan muut yhdisteet erottaa kantajasta suodattamalla, jolloin tuotteen kromatografinen puhdistus ei useinkaan ole tarpeellinen. Kantajareagensseja on myös liitetty osaksi automatisoitua synteesiä, ja menetelmät voivat tarjota ekologisen mahdollisuuden kierrättää kantaja uudelleen käytettäväksi. Tutkimusosuudessa kehitettiin täysin uudenlainen fosforyloiva kiintokantajareagenssi nukleosidivetyfosfonaattien valmistamiseen. Liuosfaasisynteesillä valmistettujen vetyfosfonaattien eristämisessä käytetään vesiuuttoa, mikä heikentää vesiliukoisten substraattien saantoja. Kehitetty menetelmä mahdollistaa vesiuuton sekä kromatografisen puhdistusvaiheen välttämisen. Taloudellinen ja suoraviivainen menetelmä voi nukleosidien lisäksi olla myös sovellettavissa muidenkin substraattien fosforylointiin. Tutkimustuloksissa kuvataan menetelmän kehityskaari, reaktioiden optimointi sekä menetelmän käyttäminen 5’-O-DMTr-tymidiini-3’-vetyfosfonaatin valmistamiseksi.
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(2023)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.
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(2024)In the theoretical part of the thesis, the main trends in the study of lipid aggregates as a pseudostationary phase in capillary electrokinetic chromatography (EKC) over the past 15 years is reviewed. Due to ability of liposomes to mimic cell membranes, they have found wide application in the biomedical field and analytical chemistry. Currently, various liposomal formulations are used as background electrolyte solutions in liposome EKC. The possibility to vary the lipid content in the lipid aggregates is increasingly expanding the usage of liposome for solving specific tasks. One of the main components of vertebrate cell membranes is cholesterol. The enormous effect of this sterol on the bilipid layer has been well studied. Properties of the lipid layer in the liposomes can be altered by changing the molar percentage of cholesterol and by this it is possible to regulate and bring the experimental conditions closer to biological conditions. In the kingdom of fungi, the function of cholesterol is performed by ergosterol. The similarity of the sterols suggests that compounds would have a similar effect on the lipid bilayer. However, comparative analyses of systems involving cholesterol and ergosterol show less obvious results. Understanding the mechanisms of drug interactions with ergosterol-containing liposomes may provide ideas for the potential development of e.g., antifungal drugs. The experimental part of the thesis describes LEKC experiments with five steroids, namely 21-deoxycortisol, corticosterone, testosterone, 17α-hydroxyprogesterone, and progesterone. Two different sets of liposome formulations containing ergosterol or cholesterol were investigated. A total of nine pairs of both liposome dispersions were used as background electrolytes for the study the interactions between the liposomes and the steroids. The experimentally determined retention coefficients and the corresponding calculated distribution constants (KD) reflected the dependency of the interaction with the lipophilicity of the analytes. With increasing lipophilicity (hydrophobicity), the affinity of the steroids to the liposomes increased, as seen by stronger interactions with the lipid phase. The average relative standard deviation of the distribution constants for each steroid was not more than 5.5% for the cholesterol-rich liposomes and 4.3% for the ergosterol-rich liposomes. The regression model of log KD Ergo vs. Log KD Chol demonstrated a linear correlation between the obtained data. The linear determination coefficient (R²) was 0.9254. Pearson's linear correlation coefficient reflected also a strong linear correlation (r = 0.9615).
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(2023)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.
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(2024)Allylamines and benzylamines are a structural class of antifungal agents, which includes three compounds: terbinafine, naftifine and butenafine. These compounds are generally used in pharmaceutical products for topical administration, although terbinafine is also available as tablets for oral administration. Chemical analysis the mentioned antifungal agents is frequently required in various fields of pharmaceutical, clinical and environmental monitoring. In relevant literature over the past 10 years, analysis of the antifungal compounds is typically performed utilising liquid chromatography together with matrix-specific sample preparation and detection methods. Simple samples, like compositionally well-defined pharmaceuticals, can be analysed with little sample preparation, while complex samples, like environmental and most clinical samples, require more extensive sample preparation. Commonly used sample preparation methods include solid phase extraction, liquid-liquid extraction and, for biological sample matrices, protein precipitation extraction. Detection of samples is typically performed with ultraviolet-visible spectrophotometry or, in the case of more complex samples, mass spectrometric devices. The experimental section reports the development and preliminary validation of a gradient elution high-performance liquid chromatographic method for the determination of terbinafine from pharmaceutical cream formulations. The analyte was extracted efficiently using strong cation exchange solid phase extraction, and detection was performed by ultraviolet-visible spectrophotometry at detection wavelengths 210 nm and 230 nm. The method achieved a limit of detection of 360 ng/mL and a limit of quantification of 690 ng/mL for the more sensitive detection wavelength 230 nm. Analyte recoveries were in the range of 103-109 %, indicating that the method is fit-for-purpose for quantitative analysis of terbinafine in cream formulations.
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(2024)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.
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(2022)Ihmistoiminnan seurauksena luonnonvesiin päätyy haitallisia metalli-ioneja, joiden aiheuttamista ongelmista kärsivät nykyään eniten köyhät ja kehittyvät maat. Metalli-ionianalytiikalla on tärkeä rooli sekä luonnonvesien tarkkailussa että tutkimisessa kuin myös teollisten prosessien laadunvalvonnassa ja kehityksessä. Induktiivisesti kytketystä plasma-massaspektrometrista (ICP-MS) on tullut yksi yleisimmistä metallianalytiikassa käytettävistä analyysilaitteista. Useiden metalli-ionien pitoisuudet vesinäytteissä ovat kuitenkin laitteen määritysrajaa matalampia, jonka vuoksi analyytit täytyy esikonsentroida mittausta varten. Lisäksi suuri liuenneen kiintoaineen määrä saattaa vahingoittaa ICP-MS -laitetta. Edellä mainitut ongelmat ovat usein ratkaistavissa kiinteäfaasiuuton avulla, josta on kehittynyt erittäin monipuolinen ja helppo esikäsittelymenetelmä erilaisten vesinäytteiden analysointiin. Tutkielman kirjallisessa osiossa perehdytään metalli-ionianalytiikan merkitykseen sekä tutkituimpien metalli-ionien ominaisuuksiin ja terveysvaikutuksiin. Osiossa esitellään yleisimpiä ja uusimpia kiinteäfaasiuuttotekniikoita sekä vertaillaan off-line- ja on-line-sovellusten erityispiirteitä. Lisäksi perehdytään tekijöihin, jotka saattavat vaikeuttaa tai haitata kiinteäfaasiuuttoprosessia ja ICP-MS -mittausta. Kirjallisen osion loppupuolella käsitellään mielenkiintoisimpia, pääsääntöisesti vuosina 2010-2022, raportoituja kiinteäfaasiuuttosorbentteja, joita on käytetty tutkimuksissa, joissa mittaus on suoritettu ICP-MS:lla. Tutkielmassa käsitellään eräiden sorbenttien ja analyysiprosessien erityispiirteitä sekä tarkastellaan tärkeimpiä analyysiparametreja. Tutkielman kokeellisessa osiossa määritettiin hopea- ja koboltti-ionipitoisuuksia ICP-MS:lla Loviisan ydinvoimalaitoksen boorihappopitoisesta primääripiirin jäähdytteestä. Ydinreaktorissa aktivoituvat hopea- ja koboltti-ionit aiheuttavat merkittävän osan voimalaitostyöntekijöiden vuotuisesta säteilyannoksesta, jonka vuoksi kyseisten ionien tarkkailulla on suora vaikutus laitosturvallisuuteen. Määritystä varten boorihappo poistettiin aluksi selektiivisellä N-metyyliglukamiinipohjaisella ioninvaihtohartsilla. Tämän jälkeen hopea- ja koboltti-ionit esikonsentroitiin iminodiasetaattipohjaisella kiinteäfaasiuuttosorbentilla. Tulosten perusteella kehitettiin esikäsittelylaittoisto, joka koostui kahdesta päällekkäin asetetusta kolonnista. Metalli-ionipitoisuudet määritettiin ICP-MS:lle kehitetyn menetelmän avulla.
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(2023)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.
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(2022)Nukleiinihapot ovat luonnollisia yksi- tai kaksisäikeisiä polymeerejä, jotka koostuvat deoksiribo- tai ribonukleosideistä linkitettynä toisiinsa fosfodiesterisidoksella. Kun tällaisia ketjuja valmistetaan kemiallisin menetelmin fosfaattiryhmä olisi aktivoitava tietyllä tavalla ja funktionaaliset ryhmät, jotka eivät osallistu reaktioon, olisi suojattava väliaikaisesti tai pysyvästi. Kiinnostus nukleiinihappokemiaan johtuu synteettisten oligomeerien ja niiden analogien kasvavasta tarpeesta välttämättöminä tutkimusvälineinä molekyylibiologiassa ja lääketieteessä. Tutkielman kirjallisessa osassa esitettiin erilaisia menetelmiä lyhyiden oligonukleotidien kemialliselle synteesille. Fosfodiesterisidosten muodostuminen tapahtuu yleensä joko fosfotriesterin tai fosfiitti-triesterin välituotteiden avulla. P(III)-välituotteiden suuremman reaktiivisuuden vuoksi fosfiitti-triesterimenetelmä ja erityisesti fosforamidiittimenetelmä ovat herättäneet huomiota. Oligonukleotidisynteesin lähtöaineiksi on ehdotettu useita erilaisia nukleosidi-fosforamidiitteja, kun on etsitty tasapainoa stabiilisuuden ja reaktiivisuuden välillä. Tämän vuoksi H-fosfonaattimenetelmää, jossa yhdistetään sekä fosfotriesteri- että fosfiitti-triesterimenetelmien edut ja lisäksi fosfodiesterimenetelmän edut (esim. fosforikeskuksen suojaavan ryhmän puute), voidaan käyttää vaihtoehtona fosforamidiittimenetelmälle erityisesti RNA:n sekä hapoille labiilien oligonukleotidianalogien synteesissä. Kaikilla menetelmillä on kuitenkin hyvät puolet sekä huonot puolet, joten ei olisi vielä olemassa yleisesti sovellettavaa ja tehokasta synteesimenetelmää, vaan ne sopivat eri tapauksiin. Esimerkiksi suuren mittakaavan synteesin tapauksessa tulee ottaa huomioon reaktioaika, reagenssi, puhdistusmenetelmä ja muut resurssit. Lisäksi lähestymistavat ovat yleensä joko erittäin työläitä etenkin lopputuotteen puhdistuksessa tai monivaiheisia sekvenssejä, joiden kokonaistuotto on alhainen. Kokeellisessa osassa valmistettiin kolmenlaisina Brønsted happokatalyytteinä pentakarboksisyklopentadieenit (PCCP). Tutkittiin mahdollisuutta käyttää PCCP-johdonnaisia regioselektiiviseen nukleosidin 5’-hydroksyyliryhmän suojaamiseen asetaaliryhmällä. Menetelmällä onnistuttiin valmistamaan tyydyttävä määrä 5’-O-asetaalisuojattua tymidiiniä. Menetelmä vaikuttaa lupaavalta pienellä jatkokehityksellä.
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(2023)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.
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(2024)Tutkielmassa käsitellään pyrimidiiniemästen, etenkin sytidiinin, suojaryhmiä nukleiinihappokemiassa. Katsauksessa tarkastellaan suojien eri ominaisuuksia, kuten niiden kiinnitystä ja poistamista, sekä millaisia olosuhteita ne kestävät. Kirjallisuuskatsauksessa käsiteltyjä suojia ovat esimerkiksi sytidiinin asyylisuoja ja karbamaattisuojat, tymidiinin bentsoyylisuoja ja uridiinin metoksietoksisuoja. Tymidiinin suojausta on tehty myös valoherkällä p-hydroksifenasyylillä, joka on varsin ainutlaatuinen. Sytidiinin tapauksessa suojaryhmiä löytyi monia erilaisia, joita voi soveltaa eri käyttökohteisiin. Kokeellisessa osuudessa on tutkittu 2’-deoksisytidiinin suojaryhmän vaikutusta liukoisuuteen käyttämällä 3,3,3-trifenyylipropionyyliryhmää emässuojana. Liukoisuuden huomattiin parantuvan huomattavasti verrattuna sytidiinin bentsoyylisuojaukseen. Lisäksi tutkimusosuudessa on valmistettu 3-(3-(bentsyylioksi)-2,2-bis(bentsyylioksi)metyylipropoksipropionihappoa, jota votaisiin mahdollisesti käyttää emässuojaryhmänä sytidiinille.
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(2021)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.
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(2024)This work focused on studying and modelling the through-diffusion and retention properties of repository basin concrete for four radionuclides common in low and intermediate level radioactive waste (LILW). With supporting C-14 PMMA autoradiography and micro-X-ray fluorescence scans, through-diffusion experiments with repository concrete samples were set up for 256 days and measured weekly with liquid scintillation counting. A model of the experimental setups was built with COMSOL Multiphysics modelling software and the experimental results were used to calculate distribution and diffusion coefficients for the studied concrete samples.
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