Browsing by Subject "Analyyttinen kemia"

Sort by: Order: Results:

Now showing items 1-20 of 61
  • Jokela, Jesse (Helsingin yliopisto, 2018)
    Tämän pro gradu –tutkielman kirjallinen osuus on katsaus aerosolimassaspektrometrian kehitystä ja sen sovelluksia käsittelevään kirjallisuuteen viimeisen noin kymmenen vuoden ajalta. Aerosolimassaspektrometrialla tarkoitetaan massaspektrometrian soveltamista aerosolihiukkasten kokojaotellun kemiallisen koostumuksen mittaukseen. Erilaiset aerosolimassaspektrometrit on tutkielmassa jaoteltu kahteen ryhmään sen perusteella, analysoidaanko laitteella yksittäisiä hiukkasia vai kerrallaan ryhmittäin useita tietyn kokoisia lyhyen ajanjakson aikana kerättyjä hiukkasia. Hiukkasia ryhmittäin analysoivat aerosolimassaspektrometrit käyttävät yleensä lämpöhöyrystystä hiukkasten desorboimiseksi ennen ionisointia, kun taas yksittäisiä hiukkasia analysoivat aerosolimassaspektrometrit desorboivat hiukkaset yksi kerrallaan käyttäen tähän tyypillisesti pulssitettua laseria. Aerosolimassaspektrometreilla voidaan tehdä monenlaista ilmakehätutkimusta. Tutkielmassa on tuotu esille erityisesti orgaanisten aerosolien ja niiden alkuainekoostumuksen, merisuolan, metallien ja muiden hivenaineiden tutkimuksia. Omat kappaleensa on annettu aerosolihiukkasten kemiallista koostumusta mittaavalle monitorille sekä aerosolimassaspektrometriin liitettäville laitteille, joita ovat esimerkiksi lämpödesorptioaerosolikaasukromatografi, potentiaalinen aerosolimassakammio ja valonsironta-moduuli. Kirjallisuuskatsauksen lopussa on käsitelty lyhyesti aerosolien lähdeanalyysejä. Ilmakehän aerosolien nukleaation, kasvun ja ikääntymisen mekanismien ja kinetiikan kvantitointi ja selventäminen edelleen ovat tarpeen, koska ilmakehän aerosolihiukkasilla on vaikutuksia maapallon ilmastoon, paikallisiin ilmansaasteisiin ja ihmisten terveyteen. Aerosolimassaspektrometreilla on keskenään hyvin erilaisia ominaisuuksia, eikä ole olemassa yhtä jokaiseen tilanteeseen soveltuvaa aerosolimassaspektrometria. Mittaukset samanaikaisesti usealla eri tyyppisellä aerosolimassaspektrometrilla ja perinteisillä analyysilaitteistoilla täydentävät toisiaan ja parantavat kokonaisvaltaisesti ymmärrystä eri menetelmistä ja hiukkasten ominaisuuksista. Tutkielman kokeellisen osuuden tarkoituksena oli mitata hiukkasten kokojaoteltuja kemiallisia koostumuksia kaupunkiympäristössä näytteenkeräys- ja suoramittausmenetelmillä, ja verrata menetelmiä keskenään. Kenttämittauksia suoritettiin nokiaerosolimassaspektrometrilla (SP-AMS). Kaskadi-impaktorilla suodatinkalvoille kerättyjä kokojaoteltuja aerosolinäytteitä analysoitiin laboratoriossa ionikromatografilla (IC). Kokeellisen osuuden suoramittaus- ja näytteenkeräysmenetelmillä mitatut kokojakaumat vastasivat pääosin melko hyvin toisiaan. Suoramittausmenetelmien ylivertainen aikaresoluutio mahdollistaa ilmakehän pienhiukkasten luonnollisten lähteiden, ihmisen aiheuttamien päästöjen sekä sääolosuhteiden vaikutusten tutkimisen huomattavan tarkasti verrattuna näytteenkeräysmenetelmiin. Virheen määrittäminen on aerosolimassaspektrometrimittauksissa selvästi vaikeampaa kuin ionikromatografia-analyyseissä. Voidaan kuitenkin varmasti sanoa, että johtuen analyysivaiheiden lukumäärästä virhe IC- ja IC-MS –mittauksissa on huomattavasti suurempi kuin SP-AMS –mittauksissa.
  • Liangsupree, Thanaporn (Helsingin yliopisto, 2018)
    The literature part of this thesis contains the review of affinity chromatography using monolithic stationary supports in the separation and isolation of biomacromolecules, a technique known as affinity monolith chromatography (AMC). Affinity chromatography is a liquid separation technique operating on the principle of reversible binding of affinity ligands and target analytes. Experimentally, affinity chromatography involves the attachment of affinity ligands to the stationary support. By selecting appropriate ligands having high affinity and specificity towards the target, selective captures of analytes of interest are made possible, allowing their isolation from complex sample matrices. Subsequently, bound analyte species are released from the ligands by employing suitable elution solutions. In addition to the specificity, monolithic stationary phases offer a number of other benefits over conventional particulate supports, i.e., improved mass transfer characteristics, allowing convective rather than diffusional transport of analytes; and high permeability, permitting operations at high flow rates without suffering from backpressure. These benefits result in substantially reduced time requirements for isolation and separation while maintaining satisfactory separation efficiency. Different types of monolithic materials, including organic polymer-based monoliths (e.g., cryogels), inorganic monoliths (e.g., silica monoliths), and hybrid monoliths have been prepared and employed in AMC. A large range of affinity ligands, e.g., proteins, antibodies, immobilized metal ions, dye ligands, have been used with monolithic supports in different formats, and in different applications. The mentioned material-related topics, as well as recent applications of AMC, are discussed in detail in this review. The experimental part of this thesis deals with the isolation of lipoproteins, and low-density lipoprotein (LDL) in particular, from human blood plasma using a newly developed AMC technique. LDL, a globular and major lipid carrier in blood, is diagnostically a highly relevant subclass of lipoproteins due to its involvement in the genesis of atherosclerosis. The currently most frequently employed method for lipoprotein isolation from blood plasma is ultracentrifugation. However, this method suffers from drawbacks, such as being time-consuming, requiring expensive equipment, and the possible exchange of lipids and lipoprotein subclasses during sample processing. Therefore, the first goal was to develop a faster LDL isolation protocol, capable of yielding LDL with good functionality and purity. Thus, the first section reports on the isolation of low-density lipoprotein (LDL) from human blood plasma by employing affinity monolith chromatography method using Convective Interaction Media (CIM) monolithic disk columns as stationary supports. Specifically, anti-apoB100-monoclonal antibody (mAb) was immobilized onto a CIM monolithic disk, providing a suitable capture medium for LDL through its major apolipoprotein, apolipoprotein B100 (apoB100). Other lipoprotein classes, namely very low-density lipoprotein (VLDL) and intermediate-density lipoprotein (IDL), also carry apoB100 and thus may be captured. To discriminate against these lipoproteins, and to obtain LDL with satisfactory purity, an additional CIM monolithic column was immobilized with a glycosaminoglycan, namely chondroitin-6-sulfate (C6S), which also binds lipoproteins, albeit with different specificity and interactions. Both of these affinity media were evaluated for LDL binding either individually or in combination. The quality of the isolated LDL was confirmed with different characterization techniques, such as size exclusion chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), enzymatic cholesterol and triglyceride assays, and enzymatic-linked immunoassays (ELISAs) specific to apolipoprotein B100 and apolipoprotein E. The results from these multi-method characterizations confirmed the successful LDL isolation with good activity. The second section of the thesis was devoted to quartz crystal microbalance (QCM) biosensor studies of LDL samples isolated from different individuals by different methods (affinity chromatography and conventional ultracentrifugation). A QCM sensor chip immobilized with anti-apoB100 mAb was used and challenged series of different LDL concentrations. The resulting sensorgrams were analyzed with a new numerical algorithm, namely Adaptive Interaction Distribution Algorithm (AIDA), permitting the determination of the number of analyte-receptor binding sites and the underlying kinetics. It was found that the obtained rate constant distributions, and clustering of antibody-LDL complexes were almost identical for all LDL samples, irrespective of sources or isolation techniques. For all samples, a total of five major complex clusters were identified. The major contributions of the two dominating clusters may arise from specific, yet heterogeneous LDL interactions at the antibody binding sites, while the other three clusters observed reflect most likely nonspecific low-affinity interactions from various sources, such as mass transfer effects, and the use of a non-orienting ligand immobilization chemistry.
  • Xue, Yu (Helsingfors universitet, 2016)
    Short-chain amines are the most common amines in the atmosphere, which are emitted from various natural and anthropogenic sources. These compounds may cause health effects through inhalation and skin contact. Short-chain amines have been analyzed from food samples, air samples, and environmental aqueous and solid samples. A variety of analytical techniques have been used for the analysis of these amines. Gas chromatography-mass spectrometry is one of the most widely used techniques, with short analysis time, and high selectivity and sensitivity. A sampling and analysis method was developed for the determination of dimethylamine from air samples. Sampling methods based on needle trap device and solid-phase microextraction were compared. Portable gas chromatography-mass spectrometry was used for sample analysis. The method with needle trap device and portable gas chromatography-mass spectrometry was selected for field measurements. The linear range of this method was 5 – 1000 ng, with correlation coefficient over 0.99. The detection limit was 3.49 ng. In field measurements, the sum of dimethylamine and ethylamine was analyzed. The relative amount of dimethylamine and ethylamine was observed to fluctuate in positive correlation with air temperature and relative humidity and in negative correlation with ozone concentration. In addition, when the relative amount of dimethylamine and ethylamine was high, it correlated negatively with total aerosol concentration.
  • Lizcano, Raymundo (Helsingfors universitet, 2013)
    In the literature part an introduction to emerging organic contaminants is presented as well as the subcategory of endocrine disrupting chemicals, which includes steroid hormones. An overview of liquid chromatography trends in environmental analysis as well as mass spectrometry operational conditions are discussed. Review is focused on ionization techniques and tandem mass spectrometry functionalities reported on state of the art studies of steroidal compounds in environmental samples. Experimental part presents an extensive sample preparation method and a liquid chromatography – mass spectrometry (HPLC-MS) method that were developed for the determination of concentration of eleven steroidal compounds: 4-androstene-3,17-dione (A1), trans-androsterone (A2), Corticosterone (C1), Cortisone (C2), Estrone (E1), 17-β-estradiol (E2), Estriol (E3), 17-α-ethynil estradiol (EE2), Progesterone (P), 17-hydroxy progesterone (HP) and Testosterone (T). Separation efficiency and analysis time were compared for three HPLC columns with different stationary phase: Pentafluorophenyl (PFP), C8 and C18 monolithic. Three atmospheric pressure ionization (API) techniques were tested to compare their performance: Electrospray ionization (ESI), Atmospheric Pressure Chemical Ionization (APCI) and Atmospheric Pressure Photoionization (APPI). The proposed method included the best column choice coupled with the API technique, which presented an efficient ionization for most of the target analytes. Best methodology was applied to the analysis of effluent and influent samples from the wastewater treatment plant in Viikinmäki, Helsinki.
  • Ekholm, Niko (Helsingfors universitet, 2016)
    Lipids are currently one of the most studied biological compounds in addition to proteins. The research field of lipidomics covers identification and quantification of lipid components in various biological systems. Lipidomics reveals answers to connection between lipid metabolism and lipid related diseases and malfunctions. Lipidomics belongs in the general group of metabolomics and is probably currently fastest growing field of so-called omic sciences. Mass spectrometric (MS) techniques have made probably highest impact on lipidomics and are gaining more and more popularity. MS has some major advantages over other conventional detection techniques. This is due to that MS allows identification and detection in lower concentration levels as well as analysis of intact lipid compounds. In the literature section, direct infusion mass spectrometric (DIMS) methods are studied from the viewpoint of lipid analysis. When direct infusion mass spectrometry is applied, the analysis is carried out by infusing the sample mixture directly into mass spectrometer without chromatographic separation and with very little sample preparation. Basic requirement for direct infusion mass spectrometric analysis is the utilization of tandem mass spectrometer in order to be measure analytes from the complex mixtures. There are two approaches in direct infusion mass spectrometry: targeted and global. DIMS is especially suitable for quick profiling and qualitative analysis of lipids, but also for quantitative analysis. The experimental part was carried out at the Neste Corporation R&D in Porvoo, Finland. Global approach for direct infusion ESI-MS/MS was studied to develop semi-quantitative profiling method for the different renewable diesel (NExBTL) feedstocks. The measured lipid classes were monoglycerides (MAG), diglycerides (DAG), triglycerides (TAG), ethyl esters (EE), wax esters (WE) and steryl esters (SE). Analytes were measured as ammonium adducts [M+NH4]+. DAG and TAG were measured with neutral loss scan (NL) and all the other classes with multiple reaction monitoring (MRM). The profiling method was developed to evaluate broader range of intact lipids for the NExBTL-process feedstock. Additional analytical methods are needed since the problems associated with the analysis are increased with the use of recycled lower price bio-oils or side streams as a feedstock, which is the upcoming trend in the field of biofuels. Study mainly consisted of fundamental work, including testing of infusion solutions, target ion selection for the mass spectrometric quantitation, mass spectrometric parameter optimization and generation of text database file, which was used as analyte database for the MRM-measured (MAG, EE, WE, SE) analytes. In addition to these, relative response factors and linearity were determined. Before the actual samples, also method performance was tested by artificial sample. Finally, analysis method was used to analyse several real samples. The results were compared to those obtained with the existing older GPC/SEC analysis method. Method showed good functionality in the quantitative or semi-quantitative level and it was taken into routine use in the R&D laboratory.
  • Burman, Jirka (Helsingfors universitet, 2013)
    Uusien mittaustekniikoiden nopea kehittyminen tuo mukanaan yhä paremmat mahdollisuudet tutkia biologisten molekyylien välisiä vuorovaikutuksia. Erityisesti lääkkeiden kehityksessä on ensiarvoisen tärkeää saada tietoa lääkeaineen ja biologisten molekyylien välisistä vuorovaikutuksista, sillä esimerkiksi lääkeaineen sitoutuminen plasman proteiineihin vaikuttaa merkittävästi lääkeaineen imeytymiseen, leviämiseen, metaboliaan ja eliminaatioon kehossa. Tärkeää on myös saada tietoa proteiini-hiilihydraatti ja vasta-aine-antigeeni vuorovaikutuksista, sillä ne liittyvät biologisiin prosesseihin, kuten hormonien toimintaan ja tunnistamiseen sekä biologisten molekyylien varastointiin. Biologisten molekyylien analytiikka on haastavaa, koska niiden aktiivisuus ja ominaisuudet usein muuttuvat niitä käsiteltäessä. Näistä mainittakoon mm. entsyymin aktiivisuus, joka saattaa kadota ja proteiinien denaturoituminen. Biosensori on analyyttinen laite, jossa biologista tai biologisesti johdettua materiaalia on joko sidottu tai kokonaan integroitu fysikaalis-kemialliseen anturiin. Biosensorien kehittämisen tavoitteena on valmistaa systeemejä, joiden avulla voidaan tutkia soluja, solukalvoja ja niiden ympäristöä reaaliajassa. Tarkoitus on saada biologisista prosesseista luotettavaa tietoa, jota hyödynnetään ihmisten hyvinvoinnin parantamiseksi. Biosensorien pitäisi olla edullisia, kestäviä, luotettavia ja lääketieteelliseen tutkimukseen soveltuvia. Tämän pro gradu -tutkielman kirjallisessa osassa tarkastellaan kvartsikidemikrovaa'an (QCM) hyödyntämistä biosensorina. QCM on laite, joka mittaa elektrodiin liitetyn kvartsikiteen värähtelytaajuutta. Kun sensorin massa muuttuu, myös sen värähtelytaajuus muuttuu. Värähtelytaajuuden muutoksesta voidaan tehdä johtopäätöksiä elektrodin pinnalla tapahtuvista muutoksista. Itsemuodostuvien pintakerrosten (SAM) avulla sensoripintaa voidaan muokata biologisten molekyylien havaitsemiseksi. SAM-pintojen käyttö perustuu kullan ja tioliyhdisteiden väliseen voimakkaaseen ja spontaaniin vuorovaikutukseen. Tioliyhdisteet muodostavat kullan pinnalle tasaisen ja stabiilin molekyylikerroksen. Tämän kerroksen ominaisuuksia muokkaamalla voidaan vaikuttaa pinnan kemiallisiin ja fysikaalisiin ominaisuuksiin. Kirjallisessa osassa käsitellään QCM:n soveltuvuutta biosensoriksi immunoglobuliini E:n ja kloramfenikolin kvantitointiin, R- ja S-enantiomeerien erotukseen, solutukirankaan sitoutuvien lääkeaineiden tutkimiseen sekä seerumin vasta-ainemääritykseen. Tulokset ovat varsin lupaavia, vaikka QCM-laitteiston herkkyys ei vielä monissa sovelluksissa oikein riitä kvantitatiiviseen määritykseen. Myös sensoripinnan uudelleenkäyttö aiheuttaa vielä ongelmia. Pro gradu -tutkielman kokeellisessa osassa sovellettiin kapillaarielektrokromatografiaa (CEC) matalatiheyksisen lipoproteiinin (LDL) ominaisuuksien tutkimuksiin. CEC:ssä käytettävien 50 µm halkaisijan avoputkisilikakapillaarien sisäpinta päällystettiin LDL:llä, joka toimi stationaarifaasina. Kehitetyllä menetelmällä tutkittiin mm. LDL:ssa tapahtuvia muutoksia sokerikäsittelyn ja hapettumisen jälkeen. Tutkimuksissa hyödynnettiin elektro-osmoottista liikkuvuutta pinnassa tapahtuvien muutosten indikaattorina. CEC osoittautui hyväksi tekniikaksi biologisella materiaalilla helposti muokattavien kapillaaripintojen, lyhyiden analyysiaikojen ja vähäisten reagenssi- ja näytemäärien ansiosta.
  • El Fellah, Samira (Helsingfors universitet, 2017)
    In the first part of this thesis the principles of capillary electrophoresis (CE) are presented from the aspects of steroid and sterol analysis focusing mainly on two separation techniques: micellar electrokinetic chromatography (MEKC) and capillary electrochromatography (CEC). Analytes are delineated in steroids, corticosteroids, phytosterols, and cholesterol. Conventional chromatographic methods: gas chromatography (GC) and high-pressure liquid chromatography (HPLC) are somewhat challenging for steroid and sterol analysis, since direct analysis of steroids/sterols and their conjugates is rarely feasible. Hence, alternative separation and analysis methods need to be approached. MEKC and CEC have provided intriguing new opportunities for steroids and sterols, respectively. The experimental part covers the study on finding out the steroid composition and concentrations of wastewater samples collected from wastewater treatment plants (WWTP) around Finland. In addition, the efficiencies of the WWTPs were resolved. There were two types of wastewater samples: influent and effluent. Influent is the unclean water and effluent is the cleaned water that has passed through the process steps. The sample pretreatment includes filtering (glass fiber and membrane filters), solid phase extraction (SPE) (with C18 (Strata-X) and quaternary amine (N+) sorbents), and liquid-liquid extraction (LLE) (with diethyl ether). SPE was effective in purifying and concentrating the water samples, with a concentration factor of 20,000. The analysis was performed with partial filling-micellar electrokinetic chromatography, utilizing UV detection. It was found that the method was suitable for both qualitative and quantitative analysis of endogenous steroids and their corresponding metabolites. Androstenedione, testosterone glucuronide, and progesterone were found from the samples. Some notable results are that biological treatment most likely increases the amount of androstenedione, whereas enzymatic processes remove efficiently progesterone. Overall, the lowest steroid concentrations were obtained from the samples of Espoo, Pori, and Uusikaupunki. On the contrary, highest concentrations were in Kajaani, Mikkeli, and Porvoo.
  • Battistuzzi, Cristina (Helsingin yliopisto, 2019)
    The large variety of shapes, functions, and conformations of proteins explains the challenges in protein identification and separation in solution. Gel electrophoresis, and more specifically SDS-PAGE, is an established technique applied to large proteins. Capillary gel electrophoresis offers the advantage of miniaturization coupled with higher speed of analysis and sample throughput. Protein analysis in silica capillaries is affected by the presence of charges on the silica surface, causing absorption, reliability and repeatability issues. Electroosmotic flow may also contribute, requiring buffer additives such as sodium dodecyl sulphate and dynamic or permanent coatings on the capillary wall. Coatings employed in capillary zone electrophoresis can be neutral or charged. They include copolymers such as poly((1-vinylpyrrolidone)-co-(2-dimethylaminoethyl methacrylate)), polyacrylamide, diazoresin as a coupling agent to form covalently bound coatings with polyvinyl alcohol, carboxyl fullerene and graphene oxide, and proprietary coatings. Capillary gel electrophoresis offers the advantages of a sieving matrix to enhance the separation of large proteins with similar charge-to-mass ratio. Dilute and semi-dilute polymer solutions with or without self-coating properties can be employed, such as polyacrylamide, polydimethyl acrylamide, and hydrophilic cellulose derivatives such as hydroxypropyl cellulose and hydroxyethyl cellulose. UV detection is enhanced by stacking techniques such as field-amplified sample stacking and the addition of sodium chloride to the sample. The focus of experimental laboratory works for this thesis was the identification of BSA, the lipoproteins HDL and LDL, and an apolipoprotein ApoB-100 using capillary gel electrophoresis. The polymer solution employed was cross-linked polyacrylamide. Instrumental factors such as run voltage, injection type, presence of sieving matrix and SDS in the BGE, sample concentration and presence of NaCl in the sample were examined. Repeatability was an issue throughout the study caused by current instability, although SDS in the BGE and addition of NaCl to the sample prior to injection had a positive effect. Stability of the BGE and the sieving matrix, together with addition of NaCl to the sample could be explored further.
  • Pesonen, Antto (Helsingfors universitet, 2012)
    The increased use of liquid biofuels has created a need for an accurate and a reliable technique for determining blend ratios of biofuel and fossil fuel due to technical reasons related to car engines and due to legislative reasons. The true portion of biological carbon in a fuel can be determined reliably only by radiocarbon measurement. Radiocarbon is created in upper atmosphere by cosmic radiation and is transferred to flora and fauna via photosynthesis. When an organism dies, the radiocarbon in its body starts do decay. Because the half-life of radiocarbon is very long and because biofuels are manufactured from relatively young feedstock materials, it is possible to calculate the biofraction of a fuel sample by determining its radiocarbon contents. The most popular techniques for determining this are, to date, accelerator mass spectrometry and liquid scintillation counting. Liquid scintillation counting is cheaper and easier to use, but in low concentrations the accuracy is not as good. In addition, the technique has the drawback of quenching effects. Accelerator mass spectrometry is the most accurate method, but the disadvantages are the price and size of the equipment and labor-intensive sample preparation process, which can take several days. In addition to the radioanalytical techniques, the biofractions of biofuels have been determined by infrared, Raman, nuclear magnetic resonance, X-ray and fluorescence spectroscopy and by gas and liquid chromatography, but these techniques have more limited applicability. In these techniques, the determination is usually based on direct or indirect detection of fatty acid methyl ester groups. However, the newer generation biofuels do not anymore contain these groups and their chemical composition is similar to fossil fuels. In addition, by using these techniques one cannot determine e.g. whether the ethanol in petrol blend is in fact manufactured from biological or fossil sources. In the experimental section of the thesis an elemental analyzer -based sample preparation method was developed, by which the time spent on sample preparation for accelerator mass spectrometer was decreased when compared to previous method, described by standard ASTM D6866-10. The biodiesel samples were combusted in the elemental analyzer and the carbon dioxide collected cryogenically. The carbon dioxide was reduced to graphite and their radiocarbon contents was measured by accelerator mass spectrometry. In addition, the results from elemental analyzer method were compared to previous results by closed-tube-combustion method. It was noticed that the elemental analyzer method was more accurate, faster and easier to use.
  • Isomaa, Keijo (Helsingfors universitet, 2013)
    This study focuses on chemometric analysis of instrumental data that has been obtained from chemical analysis of plant extracts. Chemometric analysis applies statistical and mathematical tools on chemical data, aiming to find new information or classifying samples in categories defined by the analyst. Chemometric analysis is based on computational pattern recognition and reveals any features that studied samples may have in common. In the literature part of this study, chemometrics and relevant concepts closely related to it are first explained and four commonly used chemometric methods are introduced, namely principal component analysis, hierarchical cluster analysis, k nearest neighbors and soft independent modeling of class analogy. The text is written with emphasis on being easily understandable without prior knowledge on the subject. After introducing these concepts, the literature concerning metabolomic studies of plant extracts published in the recent ten years are reviewed. This literature commonly employs chemometrics, aiming to discover if two or more varieties of the same plant species have markedly differing metabolomes and whether they can be exploited to automatically recognize these varieties. Additionally, the chemometric approaches often attempt to discover what factors are causing the successful findings. The purpose of the literature survey is to concretely show how chemometrics can achieve these goals, and to learn what the most common ways to treat the analytical data prior to chemometric analysis are. The experimental part applies chemometric methods to study bean extracts of the Ricinus communis plant, aiming to reveal if seed extracts of a same plant variety can be observed being similar, but clearly different from extracts of other varieties. Such situation could be exploited to develop a method that automatically identifies unknown seeds of the plant. The experimental work consisted of extracting homogenized samples with dilute aqueous acid, analyzing the extracts by three different instrumental techniques (liquid chromatography with ultraviolet light detection, liquid chromatography-mass spectrometry, and proton nuclear magnetic resonance spectroscopy) and finally analyzing the instrumental data by chemometric methods. Chemometrics research suffers from nonexistent standard operating procedures, since there is no universal way to treat a sample or data derived from it. While the main steps are often same, the details of sample preparation and preprocessing of analytical data vary greatly and can have a significant impact on the outcome. Despite, the data preprocessing is often left partially or completely manifested. The experimental finding was that six varieties of Ricinus communis could be successfully discriminated by both principal component analysis and hierarchical cluster analysis, applied on chromatographic data, while the results for spectroscopic data were not successful. The results encourage continuing the research, but with more emphasis on peak alignment and further experimenting with the preprocessing of the spectroscopic data. Choosing different short segments of the original spectroscopic profile is suggested, to leave out excessive information that is not helpful in discriminating the plant varieties but could obscure the relevant information.
  • Jubele, Anna (Helsingin yliopisto, 2018)
    In the first part of this thesis literature about the determination amines in food samples of the past decade (2007 – 2017) has been reviewed. The sample preparation methods and chromatographic determination methods have been reviewed. The review is focused on biogenic amines (BA) since BAs are the most relevant in food samples. Monitoring the concentration levels of BAs in foods is important because elevated levels of amine concentrations in food products can indicate spoilage which can lead to food poisoning. Food samples are complex matrices therefore sample preparation is required prior to analysis. Amine extraction methods are reviewed in more detail, including conventional solid-liquid extraction (SLE) and solid phase extraction (SPE), and novel and miniaturized methods: solid phase micro extraction (SPME), liquid phase micro extraction (LPME) and dispersive liquid-liquid micro extraction (DLLME). The derivatization methods of Bas have also been reviewed including derivatization with o - phthaldialdehyde (OPA), dansyl chloride, benzoyl chloride and diethyl ethoxymethylenemalonate (DEEMM). Chromatographic methods are well researched tools in determination of amines in food samples. In the past decade only few application were found of thin layer chromatography (TLC). The gas chromatography (GC) has been used more often, especially in the analyses of beverages. However, the high performance liquid chromatography (HPLC) is the main method of choice in determination of amines in food samples as demonstrated by the large numbers of research articles. Recently also the ultra-high performance liquid chromatography (UHPLC) has been gaining popularity. In this master’s thesis experimental part several sets of experiments were performed. Adsorbing materials were synthesized using suspension polymerization and silica gel functionalization. Compositions of materials were estimated by FTIR. The materials were characterized in terms of their suitability for amine adsorption. Ion exchange capacity was determined by titration. Static and dynamic binding capacity was determined by HPLC-UV. Derivatization studies of atmospheric amines by 9-Fluorenylmethoxycarbonyl chloride (Fmoc-Cl) were carried out by HPLC-UV. Potential imine formation was investigated by HPLC-UV. The most promising adsorbing material was a hydrolyzed copolymer of divinylbenzene and methacrylic anhydride (DVB-(MAA)2O). Its ion exchange capacity was 4.8 meq/g, static binding capacity was 0.95 mmol/g of tertiary amine and dynamic binding capacity was 2.0 mmol/g for primary amine and 0.8 mmol/g for tertiary amine.
  • Aho, Jari (Helsingfors universitet, 2008)
    The purpose of this study is to describe the development of application of mass spectrometry for the structural analyses of non-coding ribonucleic acids during past decade. Mass spectrometric methods are compared of traditional gel electrophoretic methods, the characteristics of performance of mass spectrometric, analyses are studied and the future trends of mass spectrometry of ribonucleic acids are discussed. Non-coding ribonucleic acids are short polymeric biomolecules which are not translated to proteins, but which may affect the gene expression in all organisms. Regulatory ribonucleic acids act through transient interactions with key molecules in signal transduction pathways. Interactions are mediated through specific secondary and tertiary structures. Posttranscriptional modifications in the structures of molecules may introduce new properties to the organism, such as adaptation to environmental changes or development of resistance to antibiotics. In the scope of this study, the structural studies include i) determination of the sequence of nucleobases in the polymer chain, ii) characterisation and localisation of posttranscriptional modifications in nucleobases and in the backbone structure, iii) identification of ribonucleic acid-binding molecules and iv) probing of higher order structures in the ribonucleic acid molecule. Bacteria, archaea, viruses and HeLa cancer cells have been used as target organisms. Synthesised ribonucleic acids consisting of structural regions of interest have been frequently used. Electrospray ionisation (ESI) and matrix-assisted laser desorption ionisation (MALDI) have been used for ionisation of ribonucleic analytes. Ammonium acetate and 2-propanol are common solvents for ESI. Trihydroxyacetophenone is the optimal MALDI matrix for ionisation of ribonucleic acids and peptides. Ammonium salts are used in ESI buffers and MALDI matrices as additives to remove cation adducts. Reverse phase high performance liquid chromatography has been used for desalting and fractionation of analytes either off-line of on-line, coupled with ESI source. Triethylamine and triethylammonium bicarbonate are used as ion pair reagents almost exclusively. Fourier transform ion cyclotron resonance analyser using ESI coupled with liquid chromatography is the platform of choice for all forms of structural analyses. Time-of-flight (TOF) analyser using MALDI may offer sensitive, easy-to-use and economical solution for simple sequencing of longer oligonucleotides and analyses of analyte mixtures without prior fractionation. Special analysis software is used for computer-aided interpretation of mass spectra. With mass spectrometry, sequences of 20-30 nucleotides of length may be determined unambiguously. Sequencing may be applied to quality control of short synthetic oligomers for analytical purposes. Sequencing in conjunction with other structural studies enables accurate localisation and characterisation of posttranscriptional modifications and identification of nucleobases and amino acids at the sites of interaction. High throughput screening methods for RNA-binding ligands have been developed. Probing of the higher order structures has provided supportive data for computer-generated three dimensional models of viral pseudoknots. In conclusion. mass spectrometric methods are well suited for structural analyses of small species of ribonucleic acids, such as short non-coding ribonucleic acids in the molecular size region of 20-30 nucleotides. Structural information not attainable with other methods of analyses, such as nuclear magnetic resonance and X-ray crystallography, may be obtained with the use of mass spectrometry. Sequencing may be applied to quality control of short synthetic oligomers for analytical purposes. Ligand screening may be used in the search of possible new therapeutic agents. Demanding assay design and challenging interpretation of data requires multidisclipinary knowledge. The implement of mass spectrometry to structural studies of ribonucleic acids is probably most efficiently conducted in specialist groups consisting of researchers from various fields of science.
  • Idström, Linda (Helsingin yliopisto, 2018)
    Accurate and sensitive analysis of mono-, di-, and oligosaccharides is desired in several different scientific areas due to the wide appearance of saccharides. This work focuses on the detection of mono-, di-, and oligosaccharides utilizing capillary electrophoresis (CE). Saccharide analysis with CE is challenging due to the lack of UV-absorbing chromophores in the molecular structure. CE also requires that the analytes are in their charged form, which is demanding in the case of mono-, di-, and oligosaccharides due to their high pKa-values. The first part of this work presents several detection methods and procedures to succeed in saccharide analysis with CE. A selection of the scientific work published in this area is presented to highlight the different detection possibilities. Derivatization of the analytes is commonly used to transform the saccharides into UV absorbing species. Special compositions of the background electrolyte, e.g. borate buffers and copper(II) containing buffers can be exploited to form charged complexes with the saccharides, which enhance the separation. Indirect UV detection is not as sensitive as direct UV detection of saccharide derivatives, but it is fast and useful in applications where high sensitivity is not required. Electrochemical detection (pulsed amperometric detection and contactless conductivity detection) is especially useful in miniaturized and portable systems. An advantage of electrochemical detection is also that no sample pretreatment or special reagents are required. Mass spectrometry (MS) detection is a powerful tool when detailed information about oligosaccharide structures is required and when the sample amounts are small. MS detection is therefore especially suitable in biochemical applications. In the second part of this work, CE was utilized for the separation and quantification of five novel ionic liquids and the quantification of acetate and xylose in ionic liquid matrices. The internal standard method was used in the quantitative work. The novel ionic liquids were detected with direct UV detection and the limit of detection ranged from 2-5 µg/mL. Resolution and number of effective plates were calculated from the separation studies. In the quantitative work, calibration curves were obtained for four of the novel ionic liquids. CE with indirect UV detection was used for the quantification of acetate, which is a typical counter ion in ionic liquids. A calibration curve for acetate was obtained and the linearity ranged from 0.0025 to 0.2 mg/mL. The method was successfully applied to the determination of the concentration of acetate in a standard sample containing the ionic liquid [MTBDH][OAc]. In the last part of the work, solid phase extraction was utilized to extract ionic liquids from industrial samples. CE with direct and indirect detection was used to check if the extraction was complete and if saccharides were present in the extracts. A calibration curve for xylose was constructed and the linear range for xylose was 0.05 to 3 mg/mL. It was found that the developed method for xylose detection was not sensitive enough to detect possible saccharide residues in the extracts and the analytical procedure requires further development.
  • Helin, Aku (Helsingin yliopisto, 2018)
    Short-chain aliphatic amines (SCAA) are present in multiple different matrices in the environment at low concentration levels. SCAA are considered to be environmentally relevant compounds due to their role as precursors in the formation of carcinogenic N-nitrosoamines in various matrices and new particle formation in the atmosphere. SCAA are characteristically highly volatile, polar, reactive and basic compounds. Consequently, the quantitative determination of SCAA tends to be rather challenging. In the literature part of this thesis, different analytical methods used for the determination of SCAA in environmental samples are reviewed. The typical approach for the analysis of SCAA has been the use of derivatization techniques. Derivatization converts SCAA into less polar and less volatile form, which enables the use of conventional separation techniques, such as gas chromatography (GC) and high-performance liquid chromatography (HPLC). However, the methods involving derivatization can be quite time consuming, require the usage of excess reagents and are mainly applicable for the analysis of primary and secondary SCAA. To reduce the amount of reagent and solvent consumption, microextraction techniques have been implemented as part of the derivatization methods. For the analysis of free SCAA, mainly ion chromatography (IC) and GC have been used. In recent years, also novel online mass spectrometry techniques have been used for the determination of free SCAA in atmospheric air. In the experimental part of this thesis, a novel solid-phase microextraction (SPME) device called SPME Arrow was used for the extraction of free SCAA. Different SPME Arrow sorbent materials were tested, including commercial and custom sorbents, extraction conditions were optimized and the performance of SPME Arrow was compared to conventional SPME fiber. The developed method was applied for the determination of SCAA in wastewater samples and atmospheric air samples. In general, the performance of the custom sorbent coated SPME Arrow was not adequate due to the deterioration of coating, although the preliminary results indicated possible selectivity towards dimethylamine. Considering the commercial sorbent coated SPME devices, the SPME Arrow was better than the SPME fiber in terms of limit of quantification and performance in real sample analysis. When the SPME Arrow was used for wastewater sample analysis, no matrix interferences were observed, opposite to the results obtained with the SPME fiber. In addition, the SPME Arrow could be used for the determination of SCAA in atmospheric air samples following prior preconcentration by using denuder for sampling.
  • Tsai, Chen-Yeh (Helsingin yliopisto, 2018)
    Sugar and Sugar alcohol are indicative compounds in the environmental aerosol which make them really important. The concentration of sugar and sugar alcohol reveal biogenic and anthropogenic information such as climate, air quality, wood consumption, the activity of plantation and pollution. The conventional analysis methods of sugar and sugar alcohol are reverse phase High Performance Liquid Chromatography–Mass Spectrometry (HPLC-MS/MS), and Gas Chromatography-Mass Spectrometry (GC-MS/MS). However, both of them have some limitations due to the sugar and sugar alcohol aerosol sample which are not easy to analyze. For reverse phase HPLC-MS/MS, the separation of analytes is not satisfied. For the GC-MS/MS, the derivatization process requires extra work and the derivatization compound is not stable. Besides, the matrix effect from the aerosol sample is a significant challenge which needs to be solved. Hence, the hydrophilic interaction chromatography (HILIC) and the Solid Phase Extraction (SPE) are introduced. The retention factors of HILIC column are the hydrophilic partition, the hydrogen bonding, and the electrostatic interactions. Polar stationary phase is used in HILIC mode, and the highly organic solvent is employed in mobile phase. Hence, a stagnant aqueous-rich layer is generated in HILIC mode, which can separate sugars and sugar alcohol efficiently. Furthermore, the interference and the matrix effect are solved by SPE. The development and the optimization of SPE-HILIC-MS/MS method for sugars were done in the experimental part. Eventually, the real environmental aerosol was analyzed by the optimized parameters and methods. The sugars and sugar alcohols were analyzed successfully from atmospheric aerosol samples.
  • Lehtonen, Markus (Helsingin yliopisto, 2019)
    We humans utilise many kinds of chemicals, some of them are safe to use and some of them are dangerous to use. There are chemicals that fall into grey area in the terms of safety. Surfactants are one of them. They are used abundantly and they find their ways to the environment. It is an established fact that surfactants can more or less hinder normal functions of cells, and in the worst cases can cause cell deaths. Despite of this, it is not completely understood what harm surfactants can do to the living organisms in the environment. We live and work in houses that are cleaned with washing chemicals and surfactants. Recently, surfactants were supposed to exist in indoor air, and new studies prove this hypothesis. Literature explains that there might be the possibility that surfactants can adsorb into aerosols. However, analysis methods capable to be used directly for determination of surfactants in aerosol condensate samples are not available. In this M.Sc. thesis a new surfactant determination method was developed with capillary electrophoresis using UV detection and tetraborate complex formation. First surfactant determination methods, found from the literature for environmental samples were reviewed and described in this M.Sc. thesis. Then their suitability for experimental studies was evaluated. Among many options, capillary electrophoresis coupled with ultraviolet detection was selected. The method was developed for determination of didecyldimethylammonium chloride (DDAC) and polyethylene glycol monoalkyl ether (Genapol X-80), which are representatives of cationic and nonionic surfactans, respectively, and represent the surfactants in cleaning chemicals. In the experimental work method development was focused on composition of the electolyte solutions, since they played an important roles in separation and sensitivity of the analytes. First Tricine was selected for electrolyte, because it provided the best responses in the preliminary tests. However, in the later studies it, unfortunately, proved to be unsuitable for the determination of cationic and nonionic surfactants. Therefore, in accordance with published literature tetraborate electrolyte was chosen. As application studies, we demonstrated that the studied surfactants are present in water vapour by analysing seperately DDAC and Genapol X-80 in collected water condensates by laboratory scale piloting tests.The developed method was also applied to authentic samples of indoor water condensates and washing solutions that were collected from two elementary schools with air quality issues. Surfactants were detected in these samples too.
  • Tse, Yu Tat (Helsingin yliopisto, 2018)
    The literature part of this thesis contains the review of development of portable gas chromatograph (GC) and its application in gas analysis. The scope includes portable capillary GC and chip-based GC. Gas chromatography is a separation technique based on different retention behavior of compounds in stationary phase. The use of portable GC enables chemists to carry out rapid on-site chemical analysis. Rapid, on-site analyses are valuable in fields such as air quality monitoring, emergency reaction and forensic application. Studies have shown that performance of portable GC analysis in these fields was as promising as conventional, bench-top GC analysis. The aims of portable GC development were mainly improved separation efficiency, faster analysis, greater portability, reduced power consumption, increased autonomous time and lower detection limit. Different components of portable GC are reviewed: they are separating channels/columns and stationary phases, temperature programming system, pre-concentrator, injector and detector. Semi-packed column and materials with great surface-area-to-volume ratio as stationary phase support were researched to increase surface area of retention. An improved separation efficiency was observed. Multi-channel capillary chips were fabricated to increase sample capacity of the column. Resistive heating was used in portable GC to provide high heating rate. This enables high efficiency separation in fast GC analysis. Efforts were made to reduce power consumption of the heating system to increase portable time. Using ambient air as the carrier gas eliminate the need of helium gas tank in the portable GC system. Researches were done to overcome the limitations of using ambient air. Vacuum-outlet GC technique was used to speed up the analysis. Air purification method was discussed to provide stable supply of clean air. Stability of stationary phase in ambient air was compared. A pre-concentrator is always used to lower the detection limit of gas analysis. Solid-phase microextraction (SPME) devices were commonly used. Micro-fabricated pre-concentrators were designed to enrich the analyte on-line prior to sample injection. The type of adsorbent in pre-concentrator and methods to achieve selectivity were discussed. Miniaturized detectors reported in portable GC were reviewed. Changes in the detector design were made to enhance signal quality and sensitivity in various detectors. They were made very small and light to increase portability of the GC. At last, portable GCxGC system is also mentioned. GCxGC has higher separation power than one-dimensional GC system. It allows chemist to separate analytes from complicated matrixes. Pneumatic and thermal modulation that transfer analyte bands from column to column was described. The advantages of adaptive GCxGC were also explained. The experimental part of this thesis describes a standard gas generation system of volatile organic compounds (VOCs) and its use in VOCs quantitation with internal standard, using SPME arrow as the sampler. The standard generation system was based on diffusion of analyte vapour through a deactivated capillary out of a GC vial. The vapour was carried away by nitrogen gas then diluted in various mixing ratio with nitrogen gas. The standard gas generation system can produce gas standard from any compound with high vapour pressure. The concentration of gas standard generated was validated with liquid standard. After choosing the appropriate sampling time with SPME arrow, calibration curves were constructed with conventional GC-MS and portable capillary GC-MS. Internal standard, octanal in this experiment, was generated using similar method. At various dilution factor of VOC standard, the peak area of internal standard was similar despite fluctuations. It showed the mass of internal standard extracted on the SPME arrow was relatively constant in different points on the calibration curves. Calibration curves of the VOCs with internal standard showed an improved correlation coefficient compared to calibration curves of the same VOCs without internal standard. It showed the use of internal standard in the can compensate the errors during sampling procedures. For real sample analysis, VOCs emitted from lemon sample was analyzed using the system to estimate emission rate of VOCs from lemon sample. Possible add-ons to the system were also discussed to make the system portable and reduce the uncertainty arising from variation of temperature and humidity in air during air sampling.
  • Pettersson, Annette (Helsingin yliopisto, 2019)
    Paralytic shellfish poisoning toxins belong to a group of marine biotoxins that can cause severe food poisoning. The marine biotoxins have highly varying properties, such as molecular weight, solubility and toxicity. They accumulate into shellfish during harmful algal blooms. The global fish industry monitors sea food prior to releasing them to the market to ensure the safety of consumers, and permitted levels of marine biotoxins are regulated worldwide. Possible bioterrorism use of marine biotoxins is a concern to the governments due to their high toxicity and availability. The main emphasis in this thesis is on paralytic shellfish poisoning toxins, saxitoxin and its analogues. Saxitoxin is listed under the Chemical Weapons Convention. The paralytic shellfish poisoning toxin analogues share physico-chemical properties such as solubility, but they differ highly from each other in toxicity. The most toxic analogues of paralytic shellfish poisoning toxins are the Saxitoxin and Neosaxitoxin. The toxicity of the paralytic shellfish poisoning toxins is due to the blocking of the voltage gated sodium channels, which is a reversible process. The symptoms of paralytic shellfish poisoning can be numbness, weakness and even paralysis, which can lead to respiratory failure. The paralytic shellfish poisoning can be lethal and there is no antidote. A new liquid chromatography- tandem mass spectrometric method using multiple reaction monitoring was developed. Several different hydrophilic interaction liquid chromatography type analysis columns were compared. A liquid chromatography- high resolution mass spectrometric analysis methods using full scan and product ion scan were developed for several of the paralytic shellfish poisoning toxin analogues. The limit of detection and limit of quantification for Saxitoxin analyzed with the high resolution mass spectrometry method were 0.2 ng/ml and 0.7 ng/ml respectively. In average the detection and quantification limits obtained with the high resolution mass spectrometry were around ten times better than the values obtained using triple quadrupole mass spectrometry. New sample preparation methods were developed for four different matrices (mussel, urine, milk and juice) applying solid phase extraction as the primary sample clean-up technique to be used in proficiency tests. Proficiency test samples analyzed during this thesis contained mussel, urine and unknown saxitoxin samples. The proficiency test samples were analyzed using three different chromatography-based analysis techniques to determine the presence of paralytic shellfish poisoning toxins. A comparison was done between the developed triple quadrupole mass spectrometric method, high resolution mass spectrometric method and a standardized fluorescence detection method.
  • Johansson, Maria (Helsingfors universitet, 2013)
    Dispersive liquid-liquid microextraction was developed in 2006 for the extraction of organic compounds from water samples. Since then, more complex matrices have been processed and the technique includes nowadays a variety of subsets. To the advantages of the technique are, for example, its rapidity, low cost and high enrichment factors. A pretreatment and analysis method was developed for the five harmful flame retardants, dechlorane plus (syn and anti) and dechloranes 602, -603 and -604 (component A) from solid environmental samples. The pretreatment method included extraction with pressurised liquid extraction and clean-up with multilayer silica and basic alumina columns. The analytes were separated and analysed with gas chromatography coupled to mass spectrometry. Electron capture negative ionisation was applied as the ionisation technique. The developed method was sensitive, resulting in acceptable recoveries and low detection limits. The chosen ionisation technique was proven to be superior over the more used electron ionisation.
  • Holma, Paula (Helsingfors universitet, 2017)
    Denna avhandling behandlar elektrokinetisk kapillärkromatografi (EKC) och omfattar en litteraturöversikt och en experimentell studie. Litteraturöversikten består av en inledande teoretisk genomgång av principerna för EKC. Den följs av en presentation av litteraturen rörande tillämpning av EKC vid analys av lokalbedövningsmedel. Micellär elektrokinetisk kapillärkromatografi (MEKC) är den äldsta versionen av EKC och hittills den mest använda för separation av lokalbedövningsmedel. Under de senaste åren har dock speciellt användningen av vesiklar och lipiddispersioner samt mikroemulsioner som pseudostationär fas ökat. I den experimentella delen av arbetet användes liposom elektrokinetisk kapillärkromatografi (LEKC) för att studera växelverkningar mellan bioimiterande membraner och sex lokalbedövningsmedel och ett typiskt konserveringsmedel. De bioimiterande membranerna bestod av liposomer uppbyggda av 1-palmitoyl-2-oleyl-sn-glycero-3-fosfatidylkolin (POPC) och 1-palmitoyl-2-oleyl-sn-glycero-3-[fosfo-rac-(1-glycerol)] (POPG), med eller utan kolesterol. Retentionsfaktorer och fördelningskonstanter bestämdes för samtliga analyter. Liposomernas mobilitet, vilken behövs för beräkning av analyternas retentionsfaktorer, bestämdes genom en iterativ procedur som innebar bestämning av retentionsfaktorer för en homologisk serie alkylbenzoater. Analyternas fördelning i liposomer jämfördes med litteraturvärden för fördelningen i oktanol/vatten-system. Temperaturens inverkan på växelverkningarna undersöktes genom att utföra separationer vid 25°C, 37°C och 42°C. Studierna visade att analyternas fördelning i liposomerna minskar då kolesterol tillsätts till liposomerna. Temperaturförändringen hade en smärre, osystematisk inverkan på växelverkningarna. Korrelationen mellan de experimentellt bestämda fördelningskonstanterna i liposom/vatten-system och litteraturvärden för fördelningen i oktanol/vatten-system är relativt svag.