Browsing by master's degree program "Kemian ja molekyylitieteiden maisteriohjelma"

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.

C-H bonds are abundantly present in organic compounds and therefore represent large class of targets for activation in modern synthetic chemistry. Starting from simple and usually inexpensive compounds, direct activation of C-H bonds provides atom efficient (low waste generation) access to highly functionalized products with high added value. One of the most desirable subclass of C-H bond functionalization is its transformation to C-B bond (borylation), as organoboron compounds are important and widely used building blocks in organic synthesis, in particularly pharmaceuticals, agricultural chemicals and organic materials. Traditionally, transition metal-based catalysts have been used for C-H borylation. Recently, interest has grown towards metal-free approaches. This thesis is focused on the development of metal-free Csp2-H borylation of arenes by coupling two main concepts: borenium cations and Frustrated Lewis Pairs (FLPs). Borenium cations are positively charged boron species possessing two σ-bound substituents, and the third coordination site occupied by a ligand (L) bound through coordinative dative interaction. Due to relative stability ensured by donor ligand and enhanced reactivity owing to unsaturated coordinate sphere and positive charge, chemistry of boreniums attracted considerable attention. FLPs comprise separated (intermolecular) or bound within one molecule (intramolecular) Lewis acidic and Lewis basic components, which are prevented from formation of classical Lewis adduct due to steric repulsion. Since FLPs posses unquenched reactivity they are capable to cleave heterotically σ and π chemical bonds, including C-H bonds. The method showed in the present work implies cooperative actions of 2-aminopyridinyl-borenium based FLPs, comprising borenium cation as LA component, and bulky aminopyridine ligand as LB component to borylate aromatic Csp2-H bonds. In this approach, LA serves as a reagent itself (source of boron), while LB (ligand), which abstract proton upon C-H bond cleavage, can be fully recovered from the reaction mixture. Thus, this approach offers high atom efficiency and low waste generation. We achieved borylation of electron-rich thiophenes, furans, and pyrroles under ambient conditions. Further we dedicated our efforts to improve efficiency and economical aspect of the proposed method.

Secondary Organic Aerosols (SOA), which cause adverse effects on health and climate, are formed through the oxidation of Volatile Organic Compounds (VOCs). One of the most abundant SOA precursors is α-pinene, a biogenic VOC. Eight different chamber experiments were performed in two different chambers, six experiments in ACD-C, at TROPOS, in Leipzig, and two experiments in COALA, INAR, in Helsinki to study α-pinene-derived accretion products as a result of OH and O3 oxidation with seed particles of varying acidities. The aim was to identify possible novel formation and degradation pathways of oxidation accretion products in the gas- and particle phase. It was found that more accretion products were observed in ozonolysis experiments in the particle phase and under OH oxidation and neutral seed particle conditions in the gas phase. The following degradation reactions were identified in high acidity conditions in the particle phase: C7H9O5 + C7H11O5 C14H20O8 + O2 and C7H9O5 + C10H17O4 C17H26O7 + O2. Furthermore, the contribution of HOMs to organic aerosol content was estimated for the high acidity conditions, 6.17 x 1014 molecules cm-3 ncps (normalised counts per second) for OH oxidation, and 1.02 x 1014 molecules cm-3 ncps for O3 oxidation, however, a linear growth for the formation of organic content had to be assumed.

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.

Antosyaanit kuuluvat flavonoideihin ja ne antavat hedelmille ja marjoille niiden punaiset ja siniset värit. Ne ovat luonnollisia pigmenttejä ja niiden tiedetään olevan hyviä antioksidantteja. Antosyaanit esiintyvät sekä aglykoneina ilman sokeriosaa että sokeriosan sisältävinä glykosideina. Kirjallisessa osassa esitellään viime aikoina käytettyjä uuttotekniikoita ja niiden hyödyntämistä marjojen ja rypäleiden antosyaanien ja sokerikompleksien analytiikassa. Käytettyjä uuttotekniikoita ovat kiinteä-nesteuutto, mikroaaltoavusteinen uutto, ultraääniavusteinen uutto, ylikriittinen hiilidioksidiuutto, paineistettu nesteuutto, alikriittinen vesiuutto ja kiinteäfaasiuutto. Uutto-olosuhteita ja uuttoliuottimia valittaessa on otettava huomioon antosyaanien polaarisuus, lämpöherkkyys sekä pH-riippuvuus. Antosyaaneja voidaan määrittää korkean erotuskyvyn nestekromatografialla ja ultrakorkean erotuskyvyn nestekromatografialla, joissa on käänteisfaasikolonnierotus sekä hydrofiilisen vuorovaikutuksen nestekromatografialla. Niitä voidaan määrittää myös kapillaarielektroforeesilla ja misellisellä elektrokineettisellä kapillaarikromatografialla. Kuitenkin kapillaarielektromigraatiotekniikoiden osalta tutkijat ovat keskittyneet viimeisen kymmenen vuoden aikana määrittämään marjoista ja rypäleistä muita polyfenoleja antosyaanien sijaan. Tutkielmaan on koottu kirjallisuusmateriaalia vuosien 2002–2022 ajalta. Kokeellisessa osassa marjojen (mansikka ja mustikka), rypäleiden ja viinin tutkimus toteutettiin kapillaarielektroforeesilla (CE) ja sähkösumutusionisaatio-lentoaikamassaspektrometrillä (ESI-TOF-MS). Tutkimukseen näytteet puhdistettiin kiinteäfaasiuutolla. Antosyaanit, fenoliyhdisteet ja sokerit fraktioitiin rypäle- ja viininäytteistä kiinteäfaasiuutolla Amino (NH2), StrataTM- X 3cc ja MAX 3cc uuttopatruunoilla. Sokerien kvalitatiivinen ja kvantitatiivinen analyysi suoritettiin vesifaasista CE-tekniikalla. Antosyaanien ja fenoliyhdisteiden kvalitatiivinen tutkimus suoritettiin rypäle- ja viininäytteiden metanolifaasista ja metanoli-vesifaasista ESI-TOF-MS- laitteistolla. Myös sokerit määritettiin kvalitatiivisesti, kun ne olivat ensin eluoituneet metanolifaasiin ja metanoli-vesifaasiin. Antosyaanit, fenoliyhdisteet ja sokerit määritettiin kvalitatiivisesti myös uuttamattomista mansikka- ja mustikkanäytteistä. Tutkimuksessa löydettiin kasviperäisiä sakkarideja, glykosideja, antosyaaneja ja fenoliyhdisteitä.

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.

This thesis examines the Particle-into-liquid sampler (PILS), a collection device for water-soluble aerosol components. The literature review is divided into four sections. A components section describes working mechanism of the PILS and components used in a typical PILS setup. A performance section discusses the collection efficiency, time response and resolution, background, and various other metrics of the PILS. A section on analysis methods reports on the various analytical methods uses in combination with PILS, while a research application looks at the various ways the PILS has been used in aerosol research. The experimental part focuses on untargeted analysis of water-soluble aerosol content of indoor and outdoor, using PILS for sample collection and off-line gas chromatography-mass spectrometry (GC- MS) and two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOFMS) for analysis. To increase the collection efficiency, various sampling parameters were optimized, but with no major success. Tentative identification of detected compounds revealed mostly small organic compounds: oxygen compounds, benzenoids, organic acids, hydrocarbons, lipids and lipid-like molecules and organoheterocyclic compounds.

Photocatalytic reactions utilize energy harnessed from light for the activation of a catalyst. In photoredox catalysis, an excited photocatalyst can take part in redox reactions with a substrate. The most common photocatalysts could be divided into three classes: metal catalysts, organic dyes, and heterogeneous semiconductors. These catalysts are often employed with a transition metal dual catalyst. The dual catalyst enables the cross-coupling of substrates, and the photocatalyst oxidizes or reduces the dual catalyst. Photocatalytic reactions can offer a milder alternative for the traditional C-N coupling reactions. In the literature review section, the photocatalytic N-arylation of pyrrolidines was examined. The review found that pyrrolidines were successfully N-arylated with all of the catalyst types, and multiple variations on the substituents on the aryl halide. In the majority of the research, electron withdrawing groups (EWG) as substituents enhanced product yields, but electron donating groups (EDG) decreased yields. In an organic dye catalysed reaction, the effects of the substituents were opposite. In addition, the photocatalytic reactions were compared with traditional C-N coupling reactions, such as the Buchwald-Hartwig reaction, Ullmann-type reactions nucleophilic aromatic substitution and the Chan-Lam reaction. These reactions often had harsh reaction conditions. The photocatalytic N-arylation of 3-substituted pyrrolidines was examined in the experimental part of this thesis. The objectives of this study were to investigate the use of photoredox methodologies for the C-N coupling of 3-substituted pyrrolidines to arenes and examine the scope and limitations of the reaction and the effects of substituents. In addition, the aim was to optimize the reaction conditions for multiple parameters and for each product separately, apply the reaction on a flow chemistry appliance, and execute scale-up reactions on both photoreactors. The study found 3-substituted pyrrolidines to be successfully coupled with aryl halides with great variation in the substituents of both starting materials. With optimization, the reactions with lower product yields were able to be improved significantly. The reaction was successfully upscaled, but the adaptation on the flow reactor requires further optimization. Photocatalytic C-N coupling reactions offer a promising alternative for traditional reactions.

Scandium-44 is a medically interesting positron and gamma emitting radionuclide with possible applications in molecular imaging. It is commonly produced with the use of a cyclotron in a calcium or sometimes a titanium based irradiation target. As the radiopharmaceutical use of scandium radionuclides commonly requires chelation, scandium needs to be separated from the target matrix. This is most often carried out either via extraction chromatography using a suitable solid phase or through precipitation-filtration. In this work, scandium-44 along with other scandium radionuclides was produced using cyclotron irradiation with 10 MeV protons and a solid, natural isotopic abundance calcium carbonate or calcium metal target. Scandium was separated from the irradiated targets using four different chromatographic materials and a precipitation method. Scandium-44 was produced in kilo- and megabecquerel amounts with an average saturation yield of 47 MBq/μA. The achieved separation yields in a single elution ranged from 28 ± 11 % to 70 ± 20 % with the best performing extraction material being UTEVA resin.

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.