Tyrimo objektas ir metodai: Sorbus L. genties augalo S. aucuparia L. lapų ir žiedų tyrimas. Bendras fenolinių junginių kiekis paprastojo šermukšnio augalinėse žaliavose nustatytas UV spektrofotometriniu metodu, fenolinės rūgštys ir flavonoidai nustatyti ESC metodu. Darbo tikslas: nustatyti S. aucuparia L. lapuose ir žieduose esančius fenolinius junginius, jų kiekinės sudėties įvairavimą augalo vegetacijos metu ir augalinių žaliavų (lapų ir žiedų) laikymo metu. Darbo uždaviniai: Surinkti ir susisteminti literatūros duomenis apie Sorbus aucuparia L., paprastojo šermukšnio augalinių žaliavų cheminę sudėtį, fenolinių junginių analizės metodus, poveikį ir panaudojimą medicinos praktikoje; Ištirti S. aucuparia L. lapų ir žiedų kiekybinę fenolinių junginių sudėtį ir nustatyti bendro fenolinių junginių kiekio įvairavimą augalo vegetacijos metu; Ištirti S. aucuparia L. lapų ir žiedų kokybinę ir kiekybinę fenolinių rūgščių ir flavonoidų sudėtį ir nustatyti jų kiekinės sudėties kitimą augalų vegetacijos periodo metu; Nustatyti S. aucuparia L. lapuose ir žieduose esančių fenolinių junginių kiekybinės sudėties kitimus augalinių žaliavų laikymo metu. Išvados: S. aucuparia L. augalinės žaliavos gali būti kaip šaltinis išskiriant biologiškai aktyvius junginius, kurie gali būti naudojami medicinos praktikoje. S. aucuparia L. lapuose ir žieduose esančių junginių kiekis kinta augalo vegetacijos metu; lapuose daugiausia fenolinių junginių sukaupiama gegužės - birželio mėn., žieduose – žydėjimo... [toliau žr. visą tekstą] / Object and methods: Sorbus aucuparia L. leaves and flowers study. Total amaunt of phenolic compounds in mountain ash leaves and flowers were evaluated using UV spectrophotometry, phenolic acids and flavonoids were identified and evaluated using HPLC. Aim: to identify and evaluate the content of phenolic compounds in rowan leaves and flowers during mountain ash vegetation and during plant materials (leaves and flowers) storage. Objective: to collect and organise the information about the use of Sorbus aucuparia L., S. aucuparia L. leaves and flowers acumulated compounds, phenolic compounds analysis methods and the impact of the use in medical practice; to perform quantitative analysis of S. aucuparia L. leaves and flowers phenolic compounds and to determine the total phenolics content during rowan growing season; to perform qualitative and quantitative analysis of S. aucuparia L. leaves and flowers phenolic acids and flavonoids and to determine the variation of the phenolics content during rowan growing season; to determine phenolic compounds content changes in Sorbus aucuparia L. plant materials (flowers and leaves) during them storage. Conclusions: S. aucuparia L. leaves and flower is a source of biological active substances which can be used in medicinal practice. Phenolic compounds content in S. aucuparia L. leaves and flowers change during vegetation; mainly phenolic compounds in leaves was accumulated in May - June, in flowers - in the beginning of flowering and massive... [to full text]

Dissolved organic matter (DOM) is comprised of a complex array of molecular constituents that are linked to many globally-relevant processes and yet this material is still largely molecularly uncharacterized. Research presented here attempted to probe the molecular complexity of this material from both Arctic and temperate climates via multifaceted and novel approaches. DOM collected from remote Arctic watersheds provided evidence to suggest that permafrost-disturbed systems contain more photochemically- and biologically-labile material than undisturbed systems. These results have large implications for predicted increasing temperatures where widespread permafrost melt would significantly impact stores of organic carbon in polar environments. In attempting to address the complexities and reactivity of DOM within global environments, more information at the molecular-level is necessary. Further research sought to unravel the molecularly uncharacterized fraction via use of nuclear magnetic resonance (NMR) spectroscopy in conjunction with hyphenated and varied analytical techniques. Directly hyphenated high performance size exclusion chromatography (HPSEC) with NMR was explored. This hyphenation was found to separate DOM into structurally distinct fractions but proved limited at reducing DOM heterogeneity. Of the many high performance liquid chromatography (HPLC) techniques tested, hydrophilic interaction chromatography (HILIC) was found the most effective at simplifying DOM. HILIC separations utilizing a sample from Florida resulted in fractions with highly resolved NMR signals and substantial reduction in heterogeneity. Further development with a 2D-HILIC/HILIC system to achieve additional fractionation was employed. This method produced fractions of DOM that were homogenous enough to produce excellent resolution and spectral dispersion, permitting 2D and 3D NMR experiments to be performed. Extensive NMR analyses of these fractions demonstrated strong evidence for the presence of highly oxidized sterols. All fractions, however, provided 2D NMR spectra consistent with oxidized polycyclic structures and support emerging data and hypotheses suggesting that cyclic structures, likely derived from terpenoids, are an abundant, refractory and major component of DOM. Research presented within this thesis demonstrates that HILIC and NMR are excellent co-techniques for the analysis of DOM as well as that oxidized sterols and other cyclic components with significant hydroxyl and carboxyl substituents are major constituents in DOM.

Several biologically important arsenic compounds including methylarsonate, trimethylarsine oxide, tetramethylarsonium ion, arsenobetaine and arsenocholine were prepared, in good yields, from sodium arsenite, or dimethylarsinic acid. These organoarsenic compounds together with arsenite, arsenate and dimethylarsinic acid were used as standards for the development of analytical methods for determining the levels of individual arsenic compounds (arsenic speciation) present in natural matrices. / Arsenobetaine, arsenocholine and tetramethylarsonium ion were separated by high performance liquid chromatography (HPLC) with on-line detection by thermochemical hydride generation (THG)-AAS. The analytes were eluted from the cyanopropyl bonded phase HPLC column with a 1% acetic acid methanolic mobile phase which also contained diethyl ether triethylamine, and trimethylsulfonium iodide or picrylsulfonic acid. A surface response methodology and a univariate optimization procedure were used to determine the optimum concentration of solvent modifiers in the methanolic mobile phase. Limits of detection in the range 4-5 ng (as As) were obtained for the arsonium analytes under optimum chromatographic conditions. / A simple phenol extraction procedure was developed to isolate arsonium analytes from edible marine tissues (lobster tail muscle, peeled and deveined shrimp, and cod fillet), cod liver oil and human urine. The crude extracts were separated on the cyanopropyl column using a methanolic mobile phase and detected on-line by THG-AAS. Recoveries from tissues or from urine which had been spiked at 0.1-3.4 $ mu$g of As cation/g of fresh weight were 80% or greater for each of five sample types. / An improved HPLC-AAS interface which was compatible with either aqueous or organic mobile phases was also developed. The interface provided approximately equivalent responses to different arsenic oxidation states which resulted in low to subnanogram chromatographic limits of detection for arsenic oxyanions and arsonium cations in an aqueous or methanolic mobile phase. Nascent As anions and As cations were conveniently coextracted from aqueous solution or from fish muscle by phenol extraction and quantified in the same chromatographic run. This method has been applied to a standard reference sample of dogfish muscle (DORM-1), a marine reference sediment sample (PACS-1) and to sediment porewaters (SAG-15) from the Saguenay Fjord.

A novel analytical method is developed to examine the chemical composition of plant oils by electrospray ionisation high-resolution Fourier transform ion cyclotron resonance mass spectrometry in both positive- and negative-ion modes. To date, this is the first reported application of this technique for the study of macadamia nut oil. Samples of macadamia nut oil from the Macadamia Integrifolia- Proteaceae family (smooth shell) are examined. The fatty acid profile of the oil is obtained by this mass spectrometric examination of the transesterified and hydrolysed oil samples. The Fourier transform ion-cyclotron resonance mass spectrometry results are compared to those obtained from similar samples using gas chromatography-mass spectrometry techniques. High performance liquid chromatography and Fourier transform ion cyclotron resonance mass spectrometry are used to separate and assign the isomers present in the methanol extract of the oils in separate experiments. Significant results in this study include: - The first observation and identity of a number of oxidised triacylglycerols in macadamia oil samples. - The first observation of oxidised and free fatty acids, measured directly in hydrolysed oil and in the methanol extract of macadamia oil. - High resolution Fourier transform ion cyclotron resonance mass spectrometry in broadband mode which enables isobars to be observed. - Esterified oil Fourier transform ion cyclotron resonance mass spectrometry results are consistent with our gas chromatography-mass spectrometry results and with the results of similar studies on macadamia oil in the literature. - A number of fatty acids with odd number of carbon atoms are observed in the oil. - In electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry of oils, the sample preparation is straightforward. The sample is dissolved in methanol or acetonitrile and the solution is introduced to the electrospray source directly. Introducing oil samples to the gas chromatograph-mass spectrometer needs the oils to be esterified prior to the analysis. - In this work, state-of-the-art mass spectrometry demonstrates distinct advantages in comparison to gas chromatography measurements such as direct identification of free fatty acids in oil samples, whereas this is not possible in gas chromatography-mass spectrometry due to the required esterification step prior to the analysis. - High performance liquid chromatography fraction collection is combined with Fourier transform ion cyclotron resonance mass spectrometry in off-line mode and found to improve the sensitivity, selectivity and signal to noise levels due to the lower number of compounds in each high performance liquid chromatography fraction compared to the methanol extract of macadamia oil sample. Also isomers of monoacylglycerols have been resolved using the high performance liquid chromatography technique.

Thesis (Ph. D.)--Ohio University, March, 2001. / Title from PDF t.p.

Thesis (Ph. D.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 23, 2008) Includes bibliographical references.

Thesis (Ph.D.) -- University of Western Sydney, 2002. / A thesis submitted to fulfil the requirements for the degree of Doctor of Philosophy, School of Science, Food and Horticulture, University of Western Sydney, August, 2002. Includes bibliographical references (leaves 247-260).

Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 15, 2008) Vita. Includes bibliographical references.

Thesis (MSc.(Chemistry)) - University of Pretoria, 2008. / Summary in English. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains x, 73 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references (p. 48-51).