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Browsing by study line "Kemia"

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  • Peltoniemi, Martta (2023)
    The glymphatic system is a waste clearance system in the brain to prevent protein accumulation that negatively affects neural functions, leading to neurogenerative diseases such as Alzheimer's. Perivascular spaces surround the brain vasculature allowing cerebrospinal fluid (CSF) inflow into the brain parenchyma during NREM sleep. The CSF moves from perivascular spaces into the white matter through AQP4 water channels, and flows towards the efflux routes, from where the interstitial solutes are drained into the lymphatic system. The existence and functions of the glymphatic system raise controversies due to the lack of quantitative data. Imaging tools that do not negatively affect the flow are required to visualize the glymphatic system in health and disease. If the glymphatic flow could be intensified in a preventive or therapeutic manner or harness for CNS drug delivery, it would be revolutionary. Positron emission tomography (PET) is a rising imaging modality in glymphatic research. It provides an efficient and non-invasive method, even with nanomolar tracer concentrations, to follow the CSF within the entire animal, being also fully translatable for human studies. Albumin is the dominant protein the CSF and can act as a carrier for tracers extending the circulation time. More recently, truncated Evans Blue (EB) and 4-(p-iodophenyl)butyric acid (IP) have shown promising results in modulating the pharmacokinetics of radiopharmaceuticals through albumin-binding. This study aimed to develop and evaluate six new albumin- binding tracers ( three NODAGA conjugated and three DFO conjugated) for the PET imaging of the glymphatic fluid flow via binding of endogenous albumin in the CSF. The precursors were synthesized using coupling reactions and radiolabeled with [68Ga]GaCl3 (0.2M sodium acetate buffer, pH=4, 95°C or 25°C, 15 min). Radiochemical purities were determined by radio-TLC and radio-HPLC and LogD (octanol:PBS) with shake-flask method. The in vitro stability assays were done in rat serum, rat CSF, 2 mM EDTA, and 0.2 mM FeCl3 solutions at 37°C over 6 h of incubation. The in vitro albumin binding affinities were investigated at physiological rat CSF albumin concentration at 37°C over 1 h of incubation using radio-SEC- HPLC. The in vivo and ex vivo experiments of the three most stable tracers were done using healthy female Swiss mice, and the experiments included blood kinetic studies, ex vivo biodistribution studies, and analysis of urine, bile, and blood fractions (plasma, blood cells, proteins) for in vivo stability. The precursors were synthesized with high yields (69–96%) and radiolabeled with high radiochemical yield (64– 82%), radiochemical purity (97–99.5%), and molar activities sufficient for low-volume infusion into the CSF (9.2– 17.2MBq/nmol). The NODAGA conjugated tracers had higher radiochemical yield and molar activity than the DFO conjugated tracers. The radiolabeled DFO conjugated products were stable in rat serum and rat CSF, but stability assays with EDTA and FeCl3 showed major transchelation. The NODAGA conjugated tracers were stable in each medium, maintaining the percent of intact labeled compound above 97%. The albumin binding affinity studies showed full binding from the first time point of 5 min incubation until the last time point of 1 h. The blood kinetic studies of the three stable NODAGA conjugates showed decreasing %ID/g with varying biological half- lives depending on the tracers’ lipophilic properties. The ex vivo analysis of urine and bile showed eliminated free tracer or some metabolite of the free tracer with similar retention time with radio-HPLC, no free gallium was observed. The analysis of blood samples after fractionation showed that each tracer had the most significant %ID/g in the protein fraction, and no activity was observed in the plasma. The in vivo investigated tracers showed promising properties for possible future use as CSF tracer due to high radiolabel stability and rapid stable binding to albumin in vivo.
  • Suuronen, Markus (2021)
    People spend more than 90% of time indoors. That has made the analysis of indoor air quality an subject of interest. There is a growing popularity of miniaturized sample extraction techniques utilizing solid adsorbent materials and thermal desorption allowing direct sample introduction for analysis. This approach is solvent free and there is possibility for reusing adsorbent materials depending of adsorbent properties. This thesis covers the basics of adsorption-desorption process and takes detailed look on different adsorbent materials such as activated carbon (AC), metal-organic framework (MOF) and carbon nanotubes (CNT) and evaluates the effect of surface functionality and pore size distribution for adsorption process. In experimental part, a self-made autosampler functionality and its injection parameters were optimized. The autosampler is able to independently inject up to six in-tube extraction (ITEX) needles with complete desorption. The ITEX was constructed during this experiment with TENAX-GR adsorbent and the repeatability of autosampler and ITEXs were tested and compared to commercial system with extraction of different amines. The effectiveness of this system was also demonstrated for indoor volatile organic compound (VOC) analysis.
  • Morante, Fjor (2024)
    Työn keskiössä oli tutkia reaktiota akrylaattien valmistamiseksi eteenistä ja hiilidioksidista. Kyseinen reaktio on atomiekonomian kannalta ihanteellinen, sillä siinä kahdesta runsaasti saatavilla olevasta kaasusta voidaan valmistaa käyttökelpoisia yhdisteitä. Atomiekonomialla tarkoitetaan sitä, että lähtöaineet reagoivat mahdollisimman täydellisesti halutuksi tuotteeksi. Lisäksi atomiekonomian näkökulmasta ei-toivottuja yhdisteitä ei olisi suotavaa syntyä. Atomiekonomia on yksi kahdestatoista vihreän kemian periaatteista. Tutkielmassa pyrittiin tarkastelemaan, pystyykö eteeniä ja hiilidioksidia yhdistämään käyttäen organometallikomplekseja katalyytteinä ja jos voi, minkälaiset ehdot ja olosuhteet ovat täytyttävä, jotta reaktio onnistuu. Havaittiin, että ensinnäkin eteenin on koordinoiduttava katalyyttinä käytettävään kompleksiin. Jotta eteeni koordinoituisi, on sekä metallin että ligandin oltava oikeanlaiset. Ainakin seuraavien metallien osalta koordinoitumisen on osoitettu olevan mahdollista: Cu, Ni, Pd, Mo, W, Rd, Ti ja Ru. Ligandien osalta vaihtelu on suurempaa. Yleisesti kirjallisuuden perusteella käytetyimmät ligandit ovat fosforipohjaisia, mutta myös esimerkiksi typpipohjaisia ligandejakin on raportoitu. Myös ligandin elektroneja työntävillä ja vetävillä funktionaalisilla ryhmillä on vaikutusta eteenin ja metallin väliseen koordinaatiosidokseen. Sen vaikutus voidaan havaita esimerkiksi eteenin kahden hiilen välisen sidospituuden muuttumisena sekä 1H NMR-spektristä tulkittavan eteenin siirtymän muutoksena suhteessa vapaaseen eteeniin. Eteenin koordinoitumisen jälkeen seurattiin laskettuja reaktioentalpioita apuna käyttäen, miten kompleksi voi reagoida hiilidioksidin kanssa katalyyttisesti. Katalyyttiseen sykliin kuuluu hiilidioksidin hapettava additio metalli-eteeni-kompleksiin muodostaen metallaktonirenkaan, rengasrakenteen rikkoutuminen β-H eliminaatiolla, metallin pelkistävä eliminaatioreaktio sekä lopuksi ligandin vaihto, jossa uusi eteenimolekyyli korvaa muodostuneen akrylaatin, jonka jälkeen sykli alkaa uudestaan. TON-arvo kuvaa, miten monta kertaa sykli on toistettavissa, kunnes metallikatalyytti deaktivoituu. Toistaiseksi nikkelille on raportoitu parhaimmat TON-arvot, mutta myös ruteniumille on kyseinen arvo määritetty, tosin ruteniumilla saadut arvot ovat huomattavasti heikommat. Palladiumin, molybdeenin, volframin, radmiumin ja titaanin on havaittu muodostavan metallaktonirenkaita ja joissain tapauksissa myös akrylaattia, mutta merkittävämpiä katalyyttisiä reaktioita niille ei ole vielä löydetty. Kuparin ei ole havaittu muodostavan kuparilaktonirengasta tai akrylaattia. Tutkielman kokeellisessa osuudessa oli tavoitteena tutkia, voidaanko kuparista muodostaa metallaktonirengas ja jos voi, voiko sen vapauttaa akrylaatiksi asti. Joitain kirjallisuudessa esitetyistä kupari-eteeni-komplekseista pystyttiin toistamaan, esimerkiksi [(phen)Cu(C2H4)]+ (reaktio FM-I-5B). Kirjallisuudesta saadusta tiedosta poiketen, valmistetun kompleksin eteenin 1H NMR siirtymä ei vastannut kirjallisuudessa esitettyä siirtymää. Syitä sille pohdittiin kappaleessa 3.2. Tulokset ja pohdinta. Myöskään elektroneja puoleensa vetäviä funktionaalisia ryhmiä sisältävillä ligandeilla valmistettuja kupari-eteeni komplekseja ei pystytty valmistmaan, vaikka niitä kirjallisuudessa esitettiin. Tutkielmassa kuitenkin onnistuttiin valmistamaan kaksi kompleksia (reaktiot FM-I-6A4 sekä FM-I-7A3), joita ei kirjallisuudessa oltu raportoitu. Valmistettuja kupari-eteenikomplekseja yritettiin saada reagoimaan hiilidioksidin kanssa, mutta sopivia reaktio-olosuhteita ei löydetty.
  • Meriläinen, Veronika (2022)
    As nuclear reactors come to the end of their lifetime, they undergo decommissioning. All the construction materials and spend nuclear fuel must be characterized according to their activities before final disposal. For the analysis of difficult to measure radionuclides, such as beta emitters, sample decomposition methods are used. Acid digestion, alkaline fusion and thermal combustion are examples of sample decomposition methods. In this work, alkaline fusion methods were tested to gain knowledge on the suitability of the method for volatile and non-volatile radionuclides in decommissioning waste. The sample materials tested were concrete and two difficult to dissolve reference materials: soil and coal fly ash. Results obtained with alkaline fusion were compared with that of routinely used acid digestion method. In addition, activated graphite was studied to familiarize with the analysis of difficult to measure radionuclides. Non-volatile 63Ni and 55Fe and volatile 3H and 14C were studied. The results were compared with modelled activities. Alkaline fusions were performed with a borate flux in an automated fusion oven as well as with a carbonate flux in a muffle furnace. Acid digestion was performed in an open vessel with aqua regia. The dissolved samples were analysed with ICP-OES and ICP-MS for determination of elemental concentrations. Borate fusion seemed to be the most effective method, as it was suitable for all the sample materials and released even refractory elements. Some of the volatile elements were lost during the fusion methods (Cd and Zn), while some were not affected by the high temperatures used (Pb). Alkaline fusion methods appeared to be suitable for decommissioning studies, however further research is needed. In analysis of graphite, non-volatile elements were analysed by acid digestion. 55Fe and 63Ni were separated from the matrix by hydroxide precipitation and from each other by ion exchange in an AG-resin. Ni fraction was further purified by extraction chromatography with a Ni-resin. Volatile elements were analysed by thermal combustion in a pyrolyser. The activities of 55Fe, 63Ni, 3H and 14C were measured with liquid scintillation counting. The measured activity concentrations of 63Ni were partially in agreement with the modelled values, but some samples gave higher activities. No 55Fe activities were found in any samples, as was expected based on the modelled values and the short half-life of the radionuclide. Activities of the volatile 3H and 14C were accurate and close to the modelled values. In the future, the determined activity results will be used for improving scaling factors, for the assessment of radionuclide concentrations in graphite.
  • Niskala, Iiro (2023)
    This study focuses on analyzing dust samples with gas chromatography coupled with mass spectrometer. Humans get exposed to dust daily and it is important to know the risks this exposure brings. Dust is a complex, mainly organic matrix, which absorbs compounds easily. Some of these absorbed compounds have adverse effects on human health. To identify these harmful compounds from samples, they must be extracted into a solvent and possibly cleaned, so that they can be analyzed with gas chromatography coupled with a mass spectrometer system. Analysis of dust samples requires the right gas chromatography column, which can separate analytes of interest and a mass spectrometer with an ion source that can be used to analyze the sample qualitatively and/or quantitatively depending on the depth and type of the study. Along with samples, standards are used in quality control of the analysis method and in finding limitations of the method. Methods and results of the studies used in this thesis are compiled into tables. Sources and health effects of found compounds are discussed. In the experimental part of the thesis, analysis of dust samples from Finnish museums was done for the Finnish Institute of Occupational Health. These samples were concentrated and analyzed with gas chromatography coupled with a mass spectrometer system. The system had calibration issues, which had to be solved before the data it provided was usable. After the calibration issue was fixed, the analysis results were obtained and studied. In these results many harmful compounds were found, of which many were related to the preservation of the items housed in the museums. The compounds' health effects were studied and tabulated. These results show that further studies are required for dust samples to avoid exposure to compounds found in them.
  • Kyökari, Mikko Matias (2023)
    The literature part of the thesis gives an overview of the occurrence, properties, biological activities, and analytical approaches used for the quantification of resin acids and their derivatives in tree resins, with the emphasis being on a balanced discussion of specific analytical merits and limitations. The quantification of resin acids is challenging due to their isomeric nature and limited stability, with these marker compounds being sensitive to light, oxygen, and strong acids. Methods employing reversed phase liquid chromatographic (LC) approaches in combination with UV/Vis, fluorescence, and mass spectrometric (MS) detection are covered. Gas chromatographic (GC) approaches, involving various derivatization schemes, are discussed, with detection being typically achieved by flame ionization (FI) and MS. Less frequently employed protocols, utilizing zone capillary electrophoresis with cyclodextrin additives and UV and/or fluorescence detection (FLD) are reviewed. Finally, emerging protocols employing supercritical fluid chromatography in combination with FI and MS detection are outlined. Baseline resolution of all major resin acids can only be readily achieved with GC and supercritical fluid chromatography (SFC) methods, while LC and CE protocols suffer from partial peak overlap. In terms of practical convenience, SFC may provide currently the most favorable analytical approach, obviating the need for derivatization and allowing for superior sample throughput. The objective of the experimental part of the thesis was to develop robust and expediate HPLC/UV methods for the detection and quantification of selected active marker compounds, i.e., vanillin, p-coumaric acid, pinoresinol and dehydroabietic acid, in Norwegian spruce resin extracts. Emphasis was placed on obtaining protocols characterized by operational simplicity and ready transferability to production settings. The developed methods involved continuous hot extraction of milled resin samples with 96% EtOH, followed by a simple filtration step and isocratic reversed phase HPLC/UV analysis. A preliminary validation of the developed reversed phase HPLC/UV methods was carried out to assess the limits of detection and quantification (LOD and LOQ); calibration linearity/range; precision and accuracy. LOD and LOQ values were lower than 3 µg/mL and 8.5 µg/mL for all quantified active marker compounds, respectively. To demonstrate the applicability of the developed methods, two batches of Norwegian spruce resin samples were analyzed in three replicate samples.
  • Ilmarinen, Jenni (2023)
    Sizing agents are chemical additives used in paper and board making to improve hydrophobicity and to control the water penetration into the fiber network. This thesis reviews various analytical methods that have been reported to analyze three sizing agents: alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), and rosin. Overview of the analytical methods includes gas chromatography, high-performance liquid chromatography, and Fourier transform infrared spectroscopy, along with newer techniques like ultraviolet-visible absorption spectroscopy and near infrared spectroscopy. These agents are analyzed from various paper products, like paper, process waters and dispersion. While the goal is to retain all added sizing agents within the paper or board, complete retention is not achievable, and some agents are present in process waters. Analyzing sizing agent levels in process waters allows for the evaluation of sizing agent retention. In the experimental section, Kemira Oyj's AKD analysis method for process waters from paper mills is updated. The hazardous and possibly carcinogenic extraction Solvent A is replaced with the greener and safer Solvent B. Sample preparation is improved, reducing analysis time from six hours to one. Additionally, a new high performance liquid chromatography – evaporative light scattering detector (HPLC-ELSD) method is introduced, capable of simultaneously analyzing AKD and hydrolyzed AKD (HAKD) in a single chromatogram. This is the first time a HPLC method is reported for analyzing HAKD from process waters. This method achieves 99% recovery rates with 0.2 ppm LOQ for both AKD and HAKD.
  • Youngren, Cristina (2023)
    Novichok nerve agents are persistent, highly toxic chemical weapons which were added to the Chemical Weapons Convention in 2020 after their use on civilians in England. The detection and characterization of Novichok nerve agents and the degradation products formed after their exposure to decontamination products can be accomplished through complementary instrumental analyses. Chromatographic methods such as LC-MS/MS can be utilized to qualitatively detect Novichok degradation products such as hydrolysates and LC-HRMS can provide information about their structure via the elemental composition and fragmentation pathways. By contrasting these data to spectroscopic techniques such as 1H and 31P NMR, structural elucidation of decontamination products is possible as well as the determination of the kinetics of the decontamination process itself. The literature review contains a summary of all published instrumental methods with which Novichok nerve agents, degradation products, biomarkers and adducts have been analyzed and the efficacy of those methods. In the experimental research, Novichok nerve agent A-234 was decontaminated via six different decontaminants and analyzed by LC-MS/MS to identify the mass spectra of the degradation products of each, followed by LC-HRMS analysis to determine the elemental composition and fragmentation patterns of the degradation products. The A-234 rate of hydrolysis kinetics were measured by 1H and 31P NMR spectroscopy in three of the decontaminants and when possible, two dimensional analysis was used to correlate the structural data from the chromatographic analysis. Lastly, the A-234 hydrolysate was derivatized via TMSDAM methylation for GC-MS/MS analysis after testing with two silylating and three methylating agents. Decontamination of A-234 was successful within 48 hours with three decontamination agents and complete hydrolysis was observed within 5 hours with an oxidizer-containing quaternary salt based decontamination agent.
  • Fu, Shu Yi Vicky (2022)
    Biomacromolecules are large particles found in biological fluids. The upregulations and downregulation of some biomacromolecules, such as extracellular vesicles (EVs) have been linked to cancer and infectious diseases. The study of these biological particles can help us in understanding the progression of those conditions better. Furthermore, studying naturally occurring biological molecules, e.g., immunoglobulin G (IgG), DNA, nucleic acids and glycoproteins can help us to gain more insight to important biological processes in the human body. The first part of this thesis is a literature review of monolithic columns in the separation of large biological molecules in liquid chromatographic and capillary electrochromatographic applications. Columns, including novel monolithic stationary phases, also known as monoliths, have been developed to counter some of the problems associated with the traditionally used packed beds in separation science. Monoliths have a unique structure of interconnecting porous channels, which allows faster separation with better resolution, reproducibility and mass transfer characteristics compared to packed beds. Organic-based polymer monoliths are the most widely used monolithic materials in biological applications, but the use of inorganic-based silica monoliths and hybrid monoliths have grown in the last couple of decades. Monolithic columns are versatile and they can be utilized in several chromatographic techniques, such as reversed-phase chromatography, affinity chromatography, ion-exchange chromatography, capillary electrochromatography and mixed-mode chromatography. Due to the growing interest, miniaturized monoliths e.g. in microfluidic devices, small capillaries and microarrays have been exploited to allow faster separation using sample volumes even as low as a few femtolitres. For higher sample throughput, monoliths in the format of 96-well plates, tips, sheets and disks have been introduced, especially for sample pre-treatment purposes. In the experimental part, affinity monolithic chromatography was employed for the isolation of lipoproteins and EVs in both exomere and exosome size range. The main function of EVs is transporting signal molecules from cell-to-cell to maintain homeostasis of the body. Low-density lipoprotein (LDL), very-low-density lipoprotein and chylomicrons are lipoproteins that transport different lipids in the human blood stream. The study of these particles is important because lipoproteins and especially LDL have been associated with atherosclerotic cardiovascular diseases. The experimental part of this thesis is focused on studying the feasibility of Convective Interaction Media (CIM) monoliths in disk (1.3 µm pores, 0.34 ml) and 96-well plate (2.1 µm pores, 0.1 ml) formats in purifying nanosized biomacromolecules from human plasma. The preparation of the affinity monoliths and the isolation of particles in the disk format was conducted following existing protocols and methods, which were modified for the monolithic 96-well plate. Six different monoclonal antibodies (mAbs), anti-CD9, anti-CD34, anti-CD61, anti-CD63, anti-CD81 and anti-CD82 were immobilized on the monolithic supports to target EVs. Anti-apoB100 mAb was used in targeting apolipoprotein B100 present on the surface of apoB100-containing lipoproteins. The isolation in the disk format was done using an on-line immunoaffinity chromatography – asymmetric flow field-flow fractionation method connected to ultraviolet, dynamic light scattering and diode array detectors. To compare the two different formats with different pore sizes in lipoprotein and EV isolation, the immobilization protocol and isolation conditions were optimized for the monolithic well plate. The isolation on the monolithic 96-well plate was done within 20 minutes, and the operation consumed three times less sample and buffer than in the disk format. Both monolithic formats were suitable for LDL isolation and the disks could also be used in EV isolation and separation. However, due to the larger pore size, EVs were found to be unstable in the monolithic wells.
  • Puumi, Jukka (2021)
    An overview on utilization of dual nickel/photocatalyst protocols to conduct aryl-heteroatom cross-coupling reactions is presented. Basic concepts of photocatalysis, including different relaxation pathways, the difference of singlet and triplet states, and parameters used to predict reactivity are first disclosed. The general components used in dual nickel/photocatalyst protocols are presented followed by the discussion on reactivity trends. The reactivity trends are compared with other common aryl-heteroatom cross-coupling protocols (Buchwald-Hartwig-, Ullmann- and Chan-Lam couplings) illustrating the general advantages and disadvantages of each cross-coupling method. The scope of different dual nickel/photocatalyst protocols are then explored, concentrating on cross-coupling of amines, alcohols/thiols and carboxylic acids. The developments in mechanistic understanding on the dual nickel/photocatalyst aryl-heteroatom cross-couplings in recent years are reviewed. It is concluded that photocatalytic single electron transfer-based cycles, proposed for a number of coupling protocols, are very unlikely to take place. It is made clear that, based on the current knowledge, two principle mechanism are reasonable: energy transfer or thermal Ni(I)/Ni(III) cycles. Problems concerning energy transfer mechanisms are also discussed. Finally, applicability of dual nickel/photocatalyst aryl-heteroatom cross-coupling for industrially significant transformations is briefly discussed.
  • Perera, Ileperumage Dumidu Dasun (2024)
    In biomimetic chromatography chromatographic techniques are utilized to mimic biological membranes to study the interactions between analytes and bio membranes. Immobilized artificial membrane high performance liquid chromatography (IAM HPLC) is a leading technique that is used for mimicking biological membrane-analyte interactions. Biological membranes consist of several types of phospholipids, including phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylglycerol (PG), phosphatidic acid (PA) and sphingomyelin (SM). Even though IAM HPLC is a well-established technique, its stationary phases are limited to only a few different compositions. These stationary phases that intend to mimic biological membranes, consist of only PC as a phospholipid, resulting some doubts about their mimicking ability. Open tubular capillary electrochromatography (OT-CEC) is a comparatively novel technique that also can be used for biomimicking purposes with more flexibility in the stationary phase composition. Both these techniques, their applications, pros and cons are discussed in this work. Epinephrine and norepinephrine are drugs that are widely used to treat cardiovascular collapse during resuscitation with lipid emulsions in the treatment of toxicity caused by non-local anaesthetics. The effect of the Intralipid emulsion (ILE) on the vasoconstriction induced by epinephrine or norepinephrine is however still unknown. In the experimental part of this work, the interaction of epinephrine and norepinephrine with ILE was investigated by liquid-liquid extraction (LLE) and capillary electromigration (CE) techniques. Capillary (zone) electrophoresis (CZE) was used to determine the concentrations of the analytes in the aqueous and lipid phases after LLE, and capillary electrokinetic chromatography (EKC) was performed as an alternative way to determine the distribution constants by running the analytes through a capillary filled with the ILE. The obtained distribution constants determined by LLE and EKC, suggest that epinephrine and norepinephrine are very hydrophilic compounds and that they are minimally distributed into the ILE. Therefore, their application as drugs for vasoconstriction upon ILE treatment is well motivated as they do not show significant distribution into the Intralipid emulsion. In the second part of the experimental study, the impact of different liposome compositions towards the interactions between stationary phase was studied based on the retention factors determined by OT-CEC using various stationary phase compositions. Based on the obtained results, it is evident that analyte – bio membrane interactions are highly dependent on the composition of the biomimicking membranes.
  • Känsäkoski, Silja (2023)
    Lignin is an abundant aromatic polymer found in renewable biomass sources such as trees and grasses. Lignin is largely formed as a side product in paper and pulping industries, and recent research has been trying to valorize it for value-added products such as fuels and chemicals through catalytic depolymerization. This thesis work consists of two parts: a literature review on lignin and it depolymerization methods and the experimental part where lignin is depolymerized, and the products are analyzed. In the literature review an overview of lignin, its structure and different sources is given. Furthermore, different extraction methods of lignin from the biomass source are reviewed, and more specifically the organosolv process is highlighted. Different products formed in the depolymerization of lignin are presented along with their applications. Depolymerization methods including pyrolysis, oxidative depolymerization, solvolysis and reductive depolymerization are reviewed. Finally, different metal catalysts, with a focus on molybdenum-based ones, used in reductive lignin depolymerization are presented. In the experimental part two molybdenum phosphide catalysts are synthesized and characterized. They are used in the depolymerization of fraunhoferk130 and GVL lignin using ethanolysis in a batch or autoclave reactor. The mass balance of product fractions and monophenol yields are presented. Monophenol yields ranged from 3.5 wt.% to 22.8 wt.%. Additional hydrogen pressure suppresses repolymerization and char formation but has negative impact on monomer yields so the true role of hydrogen gas remains unclear. Increasing reaction temperature led to smaller molar mass but higher char formation. The different catalysts used are compared in the results with the help of the monomer yields, mass balance and molar masses. Overall, the molybdenum-based catalysts showed promise as monomer yields were in lieu of those found in literature and can be synthesized with lower costs than noble metal catalysts.
  • Gabbouj, Selma (2022)
    Chemical attribution encompasses the detection and characterization of compounds of interest to find signature impurity, isotopic, and elemental profiles, which can be used to link illegal material to specific manufacturers, stocks, precursors, synthetic routes, or geographical locations. Explosives have been increasingly used for criminal purposes world-wide due to the availability of explosive material, precursors, and synthesis instructions. Nitrate ester, nitramine, and nitroaromatic military explosives as well as homemade organic peroxides are examples from over 250 explosive materials listed in the 2020 Federal Register of the US Bureau of Alcohol, Tobacco, Firearms, and Explosives. The first part of the thesis is a literature review, which aims to 1) present published mass spectrometric (MS) and liquid chromatographic (LC) detection methods for explosives and 2) explore chemical attribution studies of explosives and related compounds, such as illicit drugs and chemical warfare agents. The second part presents the experimental research carried out at the Finnish Institute for Verification of the Chemical Weapons Convention (VERIFIN), which aims to 3) develop an analysis method for multiclass explosives using liquid chromatography-high resolution mass spectrometry (LC-HRMS) and 4) perform chemical attribution of the nitrate ester explosive pentaerythritol tetranitrate (PETN) from different sources by isotopic and impurity profiling. Multiclass explosives detection required optimization of MS parameters, such as lower ion transfer tube and vaporizer temperatures and negative ion detection mode, as well as introduction of additives into LC eluents to promote adduct formation. PETN, 1,3,5-trinitro-1,3,5-triazinane (RDX), 1,3,5,7-tetranitro- 1,3,5,7-tetrazocane (HMX), 2,4,6-trinitrophenyl-methylnitramine (tetryl), 2-amino-4,6-dinitrotoluene (2- ADNT), and 4-amino-2,6-dinitrotoluene (4-ADNT) were detected from a mixture as nitrate adducts. Optimal parameters for the isotopic profiling of PETN were found to be 500 000 resolution, 2E4 (5 %) automatic gain control (AGC) target, and 50 ms injection time. Student’s t-tests revealed statistically significant differences between oxygen isotope ratio (18O/16O) values of PETN from two different sources. However, lack of repeatability of the isotope ratio results was an issue. 7 different methods were tested for the impurity profiling of PETN. Samples were rather pure but clear differences in the high mass range (m/z 600–900) impurity profiles of the two types of PETN were discovered, leading to the conclusion that they are indeed from different sources. Tentative structures of PETN homologue derivatives were assigned to the impurities using MS2 fragmentation and literature. Based on the results of this work, LC-HRMS is suitable for impurity analysis even for pure samples, but not very efficient or practical for analyzing isotope ratios.
  • Witharana, Dilmi (2024)
    The use of natural dyes and pigments is a practice that dates back to the beginning of civilization. With the invention of synthetic dyes, these natural dyeing practices gradually decreased due to the convenient synthesis methods and wider range of applications of synthetic dyes. However, in recent years, bio-based colourants are starting to gain more attention as green alternatives to synthetic dyes which have limitations such as environmental persistency and low biodegradability. Nevertheless, natural dyes have poor brightness and fastness properties that they tend to fade easily. To overcome these limitations, organic modifications can be done to natural colour molecules which can bring about better interactions with textile fibres. This also helps to eliminate the use of metalated mordants in the dyeing process, reducing the environmental impact. The aim of this study was to modify bio-based dyes to have better interactions with natural fibres such as wool and cellulose. This thesis will mainly focus on non-covalent dye fibre interactions. Dyes with acidic functionalities show interactions with natural fibres such as wool whereas dyes with basic functionalities interact better with cellulose fibres. Natural dyes such as quercetin, emodin and alizarin can be modified such that one or more of their hydroxyl groups are substituted with an organic moiety with various functionalities. Click chemistry is a convenient strategy to introduce these new functionalities to colour compounds. The organic moiety can be modified to achieve hydrophobicity, hydrophilicity, acidity or basicity to accommodate the dyeing process and the nature of the textile. Thus, these modified bio-based colourants offer a broader scope for potential dyeing applications.
  • Silenius, Karola (2024)
    As part of the SAFER2028, ABCRad (Alternative Buffer/Backfill Characterization and Radionuclide Interactions) research project, two alternative bentonite materials supplied by Posiva Oy were investigated in this thesis. The aim of the thesis was to investigate and determine the sorption behavior of these two buffer material candidates, with a deliberate reference to a well- known Na-Wyoming type bentonite serving as a benchmark. In order to closely imitate conditions relevant to repository settings, a synthetic reference water was prepared, and the experiments were conducted within a glove box in N2 atmosphere excluding CO2 and O2. This thesis provides valuable perspectives on the behavior and attributes of the alternative bentonite materials, which is crucial for guiding decisions in the design of repositories for radioactive waste and strategies for managing spent nuclear fuel. More specifically, this thesis provides thermodynamic sorption models (TMS) for two risk-driving radionuclides, uranium (U) and cesium (Cs). Batch sorption isotherms were made using a 1:20 solid-to-liquid ratio including 0.5 g of bentonite in 10 cm3 of reference water. Gamma spectroscopy and Liquid Scintillation Counting (LSC) were employed for the analysis of reaction supernatants. Complementary to these techniques, additional bentonite properties, including Cation Exchange Capacity (CEC) and Exchangeable Cations (EC), were determined. Pre-characterization was done for the bentonites using Fourier Transform Infrared Spectroscopy (FTIR) and the Specific Surface Areas (SSA) were determined. These analyses provide a comprehensive characterization of the alternative backfill materials under investigation. This thesis focuses on combining quantitative sorption data (e.g., distribution coefficient, Kd) with mechanistic understanding (e.g., FTIR spectroscopy). This contributes to an improved understanding of radionuclide sorption mechanisms, thereby bolstering safety considerations. The CEC determined for the bentonites, Laviosa, LMS, and Na-Wyoming were 87 (±0,048) meq/100 g, 95 (±0,34) meq/100 g, and 91 (± 1,23) meq/100 g, respectively. The distribution coefficient (Kd) values of uranium ranged from 130–135 cm3/g with Laviosa and 78–110 cm3/g with LMS, while those of cesium ranged from 130–280 cm3/g with Laviosa and from 150–425 cm3/g with LMS. Cesium demonstrated sorption of 95% within the 10-10 to 10-6 M range, decreasing slightly to 85–95% at concentrations up to 10-2 M. Uranium showed sorption in the range 80–100% across both clays, peaking at lower concentrations and declining at higher concentrations. These data align with those of the reference buffer material, indicating that these bentonites could potentially serve as feasible alternatives if they exhibit additional favorable sorption capacity with other risk-driving radionuclides (e.g., Eu, Ni, Th).
  • Lempinen, Antti (2023)
    Development of machine learning models for reaction design has garnered growing interest. Notably, the benefits of predictive models include the elimination of trial and error in selecting suitable reaction conditions. In addition, mechanistic insight may be gained to help rational catalyst design. The aim of this study is to develop modeling and parametrization method for transition metal complexes which would enable the combined parametrization of mono- and bidentate ligands for the first time. Performance of novel parametrization method is demonstrated through a ligand classification model for Suzuki–Miyaura reaction. In this literature review, an overview of the computational catalyst modeling and performance prediction is presented. The history of physical and computational chemistry is reviewed, ranging from early structure-property relationships and linear models to modern physical organic density functional theory (DFT) parameters and machine learning models. The necessary theoretical background for reaction modeling is presented in terms of transition state theory, which can be used to model selectivity or reaction rate. Additionally, the reaction yield is discussed as typical performance score for reaction modeling. Furthermore, the initial structures of typical transition metal complexes used for modeling are presented, along with the methods employed for structure optimization and ligand parametrization. By utilizing this background, the evolution of modeling methods from linear free energy relationships to machine learning is discussed. Additionally, modern classification methods for catalyst design are reviewed. Finally, the mechanistic details of Suzuki–Miyaura reaction are explored to justify the modeling methodologies in the experimental part. In the experimental study, a novel method to combine parametrization for mono- and bidentate ligands was successfully invented. As a proof of concept, performance classification of ligands for Suzuki– Miyaura reaction was conducted. Suzuki–Miyaura reaction was chosen as the model reaction due to wide data availability. Initial transition metal complexes were built according to ligation state of nickel. The initial structures always included two carbonyl ligands and either one bidentate ligand, or two monodentate ligands, or one bulky monodentate ligand. The structures were optimized with semiempirical quantum mechanical method xTB and parametrized using a newly developed in-house parametrization method. Calculated parameters include global and local steric and electronic descriptors, and local geometric descriptors. Classification models were built with selected training data. Models were used to predict the performance of new ligands. Successful results were achieved, and ligands that provided better yields were identified. In addition, it was discovered that model reaction proceeds without the presence of phosphine ligand if superbase is used as a base. Nitrogen-containing bases were screened, additional active superbases were found, and correlating descriptor with activity was detected. Based on results, more active superbases were designed.
  • Tuna, Yasemin (2023)
    Nuclear power plant decommissioning is a difficult process that combines industrial decommissioning techniques, radiation safety standards, and legal requirements for the final disposal of nuclear waste. The goal of nuclear decommissioning is to completely purge the plant of all radioactive material so that it can be released from regulatory oversight. The range of corrosion products generated on the steel surface are known to have a significant impact on the corrosion process of steel. Corrosion products have a complicated structure. The corrosion products are created when metallic components, mostly iron, react with oxygen and water that are drawn from the atmosphere, and their structure is then significantly influenced by environmental factors. Quantitative characterisation of the atomic scale structure of corrosion products is critically needed for identifying the corrosion products reliably. This thesis provides the characterization process of corrosion products formed on the steel surfaces and this process was executed with the help of XRD (X-ray Diffraction), SEM/EDS Scanning Electron Microscope/ Energy Dispersive Spectrometry, and Raman spectroscopy. Within the scope of this project, besides characterization of steel samples, Loviisa ground water and synthetic water samples which have been in a long-term contact with activated steel samples were also examined. Separation processes was carried out for determining Fe-55 and Ni-63 in the waters and the presence of Co-60 was removed from the samples before the activity determination of Fe-55 and Ni-63 by LSC (Liquid Scintillation Counting). This master's thesis has been carried out in connection with the DEMONI project, which has been a coordinated project of VTT and the University of Helsinki (KYT2022 Research Program). The outcome of the thesis will benefit possible decommissioning and disposal strategies for the nuclear power plant's reactor pressure vessels.
  • Melnik, Elena (2024)
    Mercury is a toxic heavy metal that poses significant risks to human health. In many industrial and occupational settings, employees are at high risk of mercury exposure due to the nature of their work. Consequently, biomonitoring and routine testing mercury levels in the working environment are crucial to ensure occupational health and prevent adverse health effects. This master’s thesis reviews the literature on occupational exposure to mercury and its impact on human well-being. The review focuses on the pathways through which mercury enters the body and the transformations it undergoes. Protective strategies and adopted regulations are also investigated. The analytical methods used for detection of mercury in biological samples, such as cold vapor atomic absorption spectroscopy (CV-AAS) and inductively coupled plasma mass spectrometry (ICP-MS), are explored, including comparison of their efficacy. The primary objective of the experimental part of this research was to validate the use of flow injection mercury system (FIMS) as a method for determining mercury levels in human blood and urine samples. Additionally, ICP-MS was employed for comparative analysis of mercury levels in urine samples. The analytical parameters of FIMS and the potential for selective analysis of two reducing agents, stannous chloride (SnCl2) and sodium tetrahydroborate (NaBH4), were evaluated. This process included calibration, analysis of control materials, optimization of reductant concentration, and calculation of limits of detection (LODs) and quantification (LOQs). Various approaches for the preparation of blood samples were tested. Issues associated with the incompatibility of a particular FIMS setup with the intended goals were identified, and possible solutions were proposed. The study demonstrates practical value, as it clarifies the prospects for using FIMS in the biomonitoring of mercury.
  • Ruotsalainen, Sini (2022)
    The literature review of this thesis presents the most utilized sample preparation and analysis methods for determination of trace elements from refinery feedstocks and end products during the last decade. The advantages and disadvantages of used methods and trends are presented. The challenges associated especially on silicon determination are discussed and possible solutions provided by publications are highlighted. The experimental part of this thesis is conducted in Neste’s Research and Development unit in Porvoo. The experimental part includes method development, study of siloxane compounds behavior and method validation for various sample matrices. The method development was performed by introduction of peristaltic pump to inductively coupled plasma- mass spectrometer (ICP-MS) sample introduction for two different methods (ASTM D8110M, NM 534) to replace previously used free aspiration method. The study of behavior of volatile siloxane compounds in different sample matrices including liquified waste plastics (LWP), and determination of these compounds was done with ICP-MS. The studied siloxanes showed great challenges due to their high volatility with the chosen methods. The method (ASTM D8110M, NM534) validation for different sample matrices were also done with ICP-MS. The validated matrices included several renewable matrices such as liquified waste plastics, fatty acids and other liquified waste samples and heavy fossil distillates. Repeatabilities of silicon concentration of sample as such and as spiked in intra- and inter-day, and spiked recoveries played an important role for method validation.
  • Åström, Hugo (2022)
    I discuss recent work regarding electronic structure calculations on quantum computers. I introduce quantum computing and electronic structure theory, and then discuss different mappings from electrons and excitation operators, to qubits and unitary operators, mainly Jordan–Wigner and Bravyi–Kitaev. I discuss adiabatic quantum computing in connection to state preparation on quantum computers. I introduce the most important algorithms in the field, namely, quantum phase estimation (QPE) and variational quantum eigensolver (VQE). I also mention recent modifications and improvements to these algorithms. Then I take a detour to discuss noise and quantum operations, a model for understanding how quantum computations fail because of noise from the environment. Because of this noise, quantum simulators have risen as a tool for understanding quantum computers and I have used such simulators to do electronic structure calculations on small atoms. The algorithm I have used, QPE, yields the exact result within the employed basis. As a basis I use numerical orbitals, which are very robust due to their flexibility.