Browsing by Subject "Kemi"

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  • Suuronen, Markus (Helsingin yliopisto, 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.
  • Fu, Shu Yi Vicky (Helsingin yliopisto, 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 (Helsingin yliopisto, 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.
  • Gabbouj, Selma (Helsingin yliopisto, 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.
  • Ruotsalainen, Sini (Helsingin yliopisto, 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.
  • Mustaniemi, Tuomas (Helsingin yliopisto, 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.
  • Rantanen, Noora-Kaisa (Helsingin yliopisto, 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.
  • Hoikkala, Aino (1948)
  • Junnonen, Kerttu (1975)
  • Heljala, Minna; Seppälä, Sirkka-Liisa; Elo, Tiina (Ympäristöministeriö & Lapin elinkeino-, liikenne- ja ympäristökeskus, 2013)
    Suomen ympäristö 15/2013
    Kemin kaupungin kulttuuriympäristöt löytyvät niin kaupungin ydinkeskustasta kuin sen lähiöistä ja reuna-alueilta. Kulttuuriympäristöt muuttuvat kaupungeissa kiihtyvällä vauhdilla ja siksi niiden dokumentointi on tärkeää. Ohjelmassa luodaan katsaus kaupungin kulttuuriympäristön historialliseen kehitykseen ja esitellään perustiedot rakennetun ympäristön ja arkeologisen kulttuuriperinnön nykytilanteesta. Ohjelmatyön päämääränä on tarjota tietoa kaavoituksen ja muun suunnittelun välineeksi sekä vahvistaa asukkaisen paikallisidentiteettiä ja tietoisuutta omasta ympäristöstään. Kirja toimii myös kotiseudun lukukirjana ja arvokkaiden kohteiden tietopankkina. Vastuu kulttuuriympäristöistä on niin yksityisillä ihmisillä kuin yhteisöillä.
  • Al Mussa, Wafa (Helsingin yliopisto, 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.
  • Vázquez Mireles, Sigifredo (Helsingin yliopisto, 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.
  • Mäntylä, Natalia (Helsingin yliopisto, 2021)
    The literature part of the thesis focused on reviewing published LC–MS/MS methods for cardiovascular drugs in biological matrices. Emphasis was given to the used sample preparation procedures and usability in different types of analyses, and their effects to the performances of the whole methods. Published methods for cardiovascular drugs in biological matrixes from the last decade were reviewed and presented. Insight into the challenges biological matrixes present was given, as well as a short overview of cardiovascular drugs. Plasma and urine were the most common sample matrixes, but some methods have also been published for serum and whole blood, and one even for fat tissue. Development and basic principles of liquid chromatography and mass spectrometry were presented, focusing on high and ultra-high performance liquid chromatography (HPLC and UHPLC) and triple quadrupole tandem mass spectrometry (QqQ–MS), as these seemed to be prevalent industry standard. Of sample preparation techniques, protein precipitation, direct dilution, liquid–liquid extraction (LLE), solid-phase extraction (SPE) and turbulent flow chromatography (TFC) were covered, with additions of some miniaturized versions. Some newer miniaturized online techniques have successfully been utilized for cardiovascular drug analysis, and their popularity will likely increase as the hardware in laboratories gets more and more modern. Advances in sample preparation techniques were relatively mild during the decade covered in this review, despite the significant proportion cardiovascular drugs hold in used medications. Newly published methods were either quantitative for a handful of analytes, or qualitative screenings for several analytes, some of which are cardiovascular drugs. Plasma and urine samples were used almost exclusively. In addition to the literary review, an experimental study was done at THL, where a LC–MS/MS method was successfully developed and validated during 2018–2019. The method has been used since 2019 as the primary qualitative method in cause–of–death investigations for 55 cardiovascular drugs analysed from post-mortem whole blood samples. In light of the done review, this method is exceptionally comprehensive regarding included analytes, and could potentially be at least partially automated with suitable instruments
  • Järvelä, Marjo (Helsingin yliopisto, 2022)
    Tässä työssä käsitellään orgaanisten superemästen, amidiinien ja guanidiinien, reaktiota ja hajoamisreittejä. Superemäksiä käytetään monipuolisesti orgaanisessa kemiassa, esimerkiksi vahvoina emäksinä reaktioissa, ionisina nesteinä ja katalyytteinä. Superemästen etuina verrattuna epäorgaanisiin emäksiin, on niiden alhainen vesipitoisuus ja hyvä liukoisuus orgaanisiin yhdisteisiin. Amidiinit ja guanidiinit voivat toimia reaktioissa kahdella erilaisella tavalla, sekä Brønsted emäksenä, että nukleofiilisesti. Superemäs voi toimia reaktiossa kaksoisroolissa, sekä vahvana emäksenä että nukleofiilinä. Liuottimella voidaan vaikuttaa superemäksen nukleofiiliseen käyttäytymiseen, proottiset liuottimet vähentävät niiden nukleofiilisyyttä. Liuottimena voidaan käyttää esimerkiksi vettä tai etanolia. Kirjallisuuskatsauksessa perehdytään amidiinien ja guanidiinien emäksisyyteen, valmistukseen ja hajoamiseen kemiallisissa reaktioissa sekä yhdisteiden muihin reaktioihin. Amidiinit ja guanidiinit hajoavat helposti hydrolyysissä. Muita hajoamisreaktioita ovat esimerkiksi nukleofiiliset reaktiot, joissa bisyklisen amidiinin renkaan aukeamisen seurauksena muodostuu vastaava laktaami. Superemäksestä voidaan valmistaa sen suola, ioninen neste. Ionisilla nesteillä voidaan liuottaa selluloosaa, joka on kestävä tapa valmistaa tekstiilikuituja, sillä menetelmässä voidaan kierrättää käytetty ioninen neste. Vaikka menetelmä on jo toimiva, voidaan sitä kehittää tehokkaammaksi. Kun tunnetaan eri superemästen ominaisuudet, voidaan prosessiin valita stabiilein superemäs. Superemäksestä valmistetun suolan lämpökestävyys on hyvä, mutta hydrolyysi voi aiheuttaa hajoamista ja johtaa sivutuotteiden muodostumiseen. Bisyklisestä amidiinista tai guanidiinista valmistettu ioninen neste hydrolysoituu amiiniksi ja jatkoreaktiona voi muodostua amidi. Hajoamista voidaan estää hapon avulla, mutta happo saattaa vähentää liuotuskykyä. Kokeellisessa osuudessa tutkittiin bisyklisten guanidiinien hajoamisreaktioita ja niissä muodostuvia tuotteita. Tutkittavina yhdisteinä olivat 7-metyyli-1,5,7-triatsabisyklo[4.4.0]dek-5-eeni (MTBD) ja 5-metyyli-1,5,7-triatsabisyklo[4.3.0]non-6-eeni (MTBN). Kokeissa tutkittiin niiden hydrolyysiä ja eristettiin hajoamistuotteet puhtaina aineina. Puhdistusmenetelminä käytettiin uudelleenkiteytystä ja flash-kromatografiaa. Lisäksi näiden guanidiinien hajoamistuotteille, amiineille, kehitettiin valmistusmenetelmä amideiksi. MTBD:n havaittiin hajoavan hydrolyysin vaikutuksesta kahdeksi isomeeriksi. MTBN:n koostuessa kahdesta isomeerista oletuksena oli, että se voisi hajota kuudeksi eri isomeeriksi. Tutkimuksessa kuitenkin huomattiin, että se hajoaa pääosin kahdeksi isomeeriksi. MTBD:n ja MTBN:n amiineista valmistettiin amidit, ja molempien superemästen toisesta amiinin isomeerista muodostui asyloitaessa kaksi amidin isomeeria.
  • Uosukainen, Moona (Helsingin yliopisto, 2021)
    Haihtuvia yhdisteitä, mukaan lukien haihtuvia orgaanisia yhdisteitä, tuottavat sekä ihmiset että mikrobit osana niiden normaalia aineenvaihduntaa. Ihmiskehossa joko normaalisti tai esimerkiksi bakteeri-infektion johdosta syntyneet haihtuvat yhdisteet pystyvät kulkeutumaan veren mukana läpi ihmiskehon, ja päätyä esimerkiksi verestä keuhkorakkuloiden kautta uloshengitettävään ilmaan tai munuaisten kautta virtsaan, jolloin niiden läsnäolo on mahdollista havaita näistä näytematriiseista. Myös bakteerit voivat päätyä esimerkiksi verenkiertoon tai virtsateihin, jolloin niiden muodostamia haihtuvia yhdisteitä voidaan mahdollisesti havaita näistä näytematriiseista ja yhdisteitä voitaisiin käyttää indikaattorina esimerkiksi tietyn taudinaiheuttajan läsnäolosta. Tämän tutkielman kirjallisuusosuudessa tutustutaan mikrobiperäisten haihtuvien yhdisteiden potentiaaliin ja haasteisiin diagnostiikassa. Bakteerien tuottamia yhdisteitä voidaan tutkia erilaisilla in vitro-malleilla, jolla tarkoitetaan bakteerien kasvattamista ihmiskehon ulkopuolella esimerkiksi kasvatusliuoksessa tai kliinisissä matriiseissa. Tämän avulla bakteerien tuottamia yhdisteitä voidaan tutkia ilman mahdollisia ihmiskehon aikaansaamia isäntävasteita bakteereille ja näin tutkia tietyn taudinaiheuttajan eli patogeenin tuottamia merkkiaineyhdisteitä. Toinen lähestymistapa on tutkia esimerkiksi tiettyä sairautta potevan ihmisen uloshengitysilmaa ja pyrkiä erottamaan tiettyä sairautta potevat terveistä henkilöistä. Kirjallisuusosassa käydään läpi haihtuvien yhdisteiden analytiikassa käytettyjä analyysimenetelmiä sekä niiden etuja ja rajoituksia verrattuna kaasukromatografia-massaspektrometriaan (GC-MS). Tässä tutkielmassa käydään myös läpi suun patogeenisten bakteerien, tarkemmin sanottuna hampaiden kiinnityskudoksia tuhoavaan parodontiittiin liitettyjen bakteerien roolia taudinaiheuttajina, bakteerien tuottamia haihtuvia yhdisteitä sekä yhdisteiden mahdollista biologista alkuperää. Suun patogeeniset bakteerit ja parodontiitti voivat aiheuttaa myös lukuisia muita sairauksia, joten suun patogeenien tunnistaminen on yksi haihtuvien yhdisteiden analytiikan potentiaalinen sovellutusalue. Sen lisäksi, että näillä haihtuvilla yhdisteillä on potentiaali diagnostiikassa olla tiettyä patogeenia indikoivia merkkiaineyhdisteitä, ne ovat myös osallisena parodontiitin syntymisessä sekä etenemisessä. Tutkielman kokeellisessa osassa identifioitiin suun patogeenisten anaerobisten bakteerien tuottamia haihtuvia yhdisteitä in vitro käyttämällä kiinteäfaasimikrouutto-kaasukromatografi-massaspektrometriä (SPME-GC-MS). Mittauksia varten rakennettiin näytteenottosysteemi, jonka avulla yhdistettiin bakteeriviljely, SPME-näytteenotto sekä yhdisteiden reaaliaikainen analyysi protonisiirtoreaktio-massaspektrometrillä (PTR-MS). Työn tarkoituksena oli tutkia, millaisia haihtuvia yhdisteitä suun bakteerit tuottavat ja tuottavatko bakteerit sellaisia yhdisteitä, joita voidaan mahdollisesti käyttää kyseisiä bakteereja indikoivina merkkiaineyhdisteinä tulevaisuudessa. Tutkimuksessa identifioitiin kahden patogeenin, jotka olivat Porphyromonas gingivalis ja Prevotella nigrescens, tuottamat haihtuvat yhdisteet ja molemmille bakteereille löydettiin kaksi potentiaalista merkkiaineyhdistettä, joiden avulla bakteerit voidaan erottaa toisistaan sekä mahdollisesti muista suun patogeeneista. P.gingivalis tuotti kaksi spesifistä esteriä, isoamyyli asetaattia ja isoamyyli propionaattia, ja P.nigrescens 3-(metyylitioli)propionaalia sekä 2-metyylibutaanihappoa. Tutkimuksen perusteella ei voida kuitenkaan tehdä laajoja johtopäätöksiä, koska kyseisissä analyysi- ja bakteeriviljelyolosuhteissa on analysoitu vain kahden patogeenisen bakteerin tuottamat yhdisteet, sillä kahden muun tutkimukseen valitun bakteerin viljely ei onnistunut.
  • Parviainen, Riku (Helsingin yliopisto, 2022)
    The literature section of this thesis provides an overview of modern ion-mobility spectrometry techniques in context with recent applications in analytical chemistry. While ion-mobility spectrometry is an “old” separation technique, it has received in recent years increasing attention for its unique ability to achieve separation of isomeric molecular species. Ion-mobility spectrometry can be readily hyphenated with chromatographic and mass spectrometric techniques, introducing an additional separation dimension with the unique capability of differentiating isobaric analyte ions based on their collision cross sections. After a brief introduction into the theory of ion-mobility spectrometry, most recent applications in the field are presented with the focus being on the discrimination of small isomeric molecules. The research project section of the thesis reports the synthesis of isomerically pure standard materials of the commercially unavailable pepper alkaloids piperettine and piperettyline, and the qualitative and quantitative analysis of piperettine in selected pepper fruit samples. Strategies for the synthesis of piperettine reported in the literature are reviewed, and critically evaluated in terms of practicability and overall yields. A new, expedient, and operationally convenient synthetic approach to isomerically pure piperettine and piperettyline from inexpensive starting materials is described. In course of stability studies, both alkaloids were found to be stable in the crystalline states and as solutions in a range of organic solvents under exclusion of ambient light. However, diluted solutions of both compounds proved extremely photosensitive, with extensive double bond isomerization occurring within seconds upon sunlight exposure. An analytical method for the quantification of piperettine in pepper fruit samples was developed, involving liquid extraction, extract clean-up by solid-phase extraction, and HPLC-UV analysis. The use of a chiral stationary phase (Chiralpak IB) under optimized reversed phase condition allowed for the first time clean separation of piperettine from its naturally co-occurring isomers, and thus for its unambiguous quantification. Subsequently, this method was employed to quantify piperettine in black, green, white, and red long pepper samples. The observed piperettine content were 1.4 – 3.7 mg/g in the pepper fruit samples, representing 46 – 69% of the total sum of isomers.