Lipid metabolism is critically important to the normal function of individual cells and for signaling between tissues of the human body. There is a great need to quantify changes in lipid metabolism because of its implications in both normal healthy conditions and during disease development. In our first study, we developed a liquid chromatography mass spectrometry based workflow to assess in vivo metabolism of murine brain lipids. This involved sample preparation, data acquisition, and analysis software development and improvements. Regarding sample preparation, we maintained the mice at 5% body water for the duration of the experiment. As mouse metabolism proceeds, enzymes can add deuterium atoms (D) from D2O into lipid C-H bonds. These newly synthesized D-labeled lipids display shifts in their isotopic envelopes. To observe these shifts, we used mass spectrometry acquisitions to measure the mass spectra of isotopic envelopes. We calculated changes in these isotopic envelope shifts to deduce several metabolic metrics. We used these metabolic metrics to make inferences about metabolism changes. These metrics include n-value, fraction new, rate, and asymptote for each lipid. We deduced n-value by replacing one hydrogen with a deuterium at a time in the lipid's theoretical chemical formula. The number of deuterium atoms in the theoretical D-labeled chemical formula that agrees best with its respective empirical spectrum is the n-value. A large part of this effort was assessing the reproducibility and quality control of n-values that were derived from empirical spectra. We compared these n-values to two sets of ground truth n-values that we generated. We generated one set of ground truth n-values by referencing biochemical pathways and published n-values. We used a linear algebra approach to deduce the other set of ground truth n-values. We compared both sets of ground truth n-values to n-values derived from empirical D-labeled lipid spectra. We found that both sets of ground truth n-values correlate well with n-values from empirical spectra. Using these n-values, we calculated fraction new for each lipid. This fraction new indicates what percentage of a lipid's pool is newly synthesized at a given time. For a given lipid, we calculated the fraction new for each time point and biological replicate. We plotted these fraction values together against time in days. From this fraction new vs time plot for each lipid, we deduced its asymptote and rate constant. In our second study, we added the additional dimension of drift time to the data acquisition and analysis using ion mobility spectrometry. We added this additional dimension so that we could further separate lipid isomers and prevent spectral convolution. Preliminary results suggest that lipid isomers may have distinct metabolic regulation.

This thesis is a summary of five papers with focus on adsorption processes of various monocarboxylates and aminocarboxylates at the water/goethite interface. Interaction of organic acids at the water/mineral interfaces are of importance in biogeochemical processes, since such processes have potential to alter mobility and bioavailability of the acids and metal ions. In order to determine the coordination chemistry of acetate, benzoate, cyclohexanecarboxylate, sarcosine, MIDA (methyliminediacetic acid), EDDA (ethylenediamine-N,N’-diacetic acid) and EDTA (ethylenediamine-N,N’-tetraacetic acid) upon adsorption to the goethite (alpha-FeOOH) surface, a combination of quantitative measurements with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was utilized. Over the pH range studied here (pH 3- 9) all ligands, except for sarcosine, have been found to form surface complexes with goethite. In general, theses were characterized as outer sphere surface complexes i.e. with no direct interaction with surface Fe(III) metal ions. Furthermore, two types of different outer-sphere complexes were identified, the solvent-surface hydration-separated ion pair, and hydration-shared ion pair. For the monocarboxylate surface complexes distinction between these two could be made. At high pH values the solvent-surface hydration-separated ion pair was the predominating complex, while at low pH the surface complex is stabilized through the formation of strong hydrogen bonds with the goethite surface. However, it was not possible to clearly separate between the two outer-sphere complexes for coordination of the aminocarboxylates with the surface of goethite. Additionally, EDDA also formed an inner-sphere surface complex at high pH values. The EDDA molecule was suggested to coordinate to the surface by forming a five membered ring with an iron at the goethite surface, through the amine and carboxylate groups. Contrary to the other ligands studied, EDTA significantly induced dissolution of goethite. Some of the dissolved iron, in the form of the highly stable FeEDTA- solution complex, was indicated to re-adsorb to the mineral surface as a ternary complex. Similar ternary surface complexes were also found in the Ga(III)EDTA/goethite system, and quantitative and spectroscopic studies on adsorption of Ga(III) in presence and absence of EDTA showed that EDTA considerably effects speciation of gallium at goethite surface. The collective results in this thesis show that the affinity of these ligands for the surface of goethite is primarily governed by their chemical composition and structure, and especially important are the types, numbers and relative position of functional groups within the molecular structure.