A Comprehensive Analytical Approach for Characterizing the Impacts of Climate Change on Carbon Sequestration in Peatlands
Bill Cooper#, Suzanne Hodgkins#, Rachel Wilson*, Kelsey Rogers*, Jeff Chanton*
#Department of Chemistry & Biochemistry, Florida State University
*Department of Earth, Ocean and Atmospheric Science, Florida State University
Peatlands represent the largest stores of sequestered carbon on earth. The majority of global peatlands are found in boreal regions, where low temperatures and saturated soils preserve organic matter. Nonetheless, peat deposits exist at subtropical and tropical latitudes, where much warmer temperatures would be expected to promote rapid decomposition and thus inhibit peat accumulation. Mechanisms that protect natural organic matter (NOM) from microbial decomposition and release to the atmosphere as carbon dioxide and methane are not well understood, particularly the relationships between NOM composition and microbial enzyme expression. Of particular concern is how these mechanisms will be altered as global warming proceeds. In this presentation we will summarize results of comprehensive analytical characterization of NOM in peatlands across a hemispheric latitudinal gradient ranging from sub-arctic Sweden to tropical Borneo. Characteristics of solid phase organic matter (SOM) were identified by Fourier transform infrared spectroscopy (FTIR) and solid state 13C NMR (SS-NMR), while dissolved organic matter (DOM) in soil porewaters was characterized by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and excitation-emission matrix spectroscopy coupled with parallel factor analysis (EEM-PARAFAC). Results to date suggest strong correlations between preservation of NOM and its composition, as well as the microbial enzymes being expressed. These data further indicate that remineralization of peatland NOM to CO2 and CH4 may be more complicated than originally thought.
ELECTRODEPOSITION AND CHARACTERIZATION OF MANGANESE DIOXIDE ON GOLD NANOTUBES
Juliette Experton, Xiaojian (James) Wu, Charles R. Martin
Department of Chemistry, University of Florida, Gainesville, FL 32611
Bipolar electrochemistry is a powerful tool capable of localized and asymmetric electrodeposition on nano-objects in the absence of electrical contact. It offers a precise way to grow oxide nanoparticles on 3D substrates. We have developed a technique to synthesize MnO2 particles using bipolar electrochemistry at a low voltage (3.5 V). This voltage is applied across a gold nanotube membrane forming redox reactions, one cathodic and one anodic, at either end of the nanotube. The anodic reaction is chosen such that it forms MnO2 at the pore orifice. The resulting capped pores were used for the electrochemical analysis of MnO2 to determine its conductivity, surface charge and permselectivity. In this presentation, we will address the performance of this material for applications in batteries and catalysis.
Discovery and Targeted Monitoring of Lipids Under Different Cell Conditions using a Multidimensional Analytical Approach
Kendra J. Adams1, Cesar E. Ramirez1, Richard H. Gomer2, Francisco Fernandez-Lima1,3
1. Department of Chemistry & Biochemistry, Florida International University, Miami, FL
2. Department of Biology, Texas A&M University, College Station, TX
3. Biomolecular Sciences Institute, Florida International University, Miami, FL
The complexity of biological matrices demands the use of complementary analytical tools for separation, identification and quantitation of single components. For example, traditional lipid analysis is based on the use of liquid chromatography coupled to mass spectrometry (LC-MS/MS) for separation and identification based on the molecular mass and fragmentation pattern; however, reproducibility and the need for long separation times reduces the throughput of this technique. In order to overcome these challenges, a multidimensional separation technique is proposed based on the use of trapped ion mobility spectrometry coupled to mass spectrometry (TIMS-MS/MS) as a screening and quantification tool. In the present work, we compare traditional LC-MS/MS with TIMS-MS/MS workflows for the separation and detection of lipids from Dictyostelium discoideum cells at different developmental stages. TIMS-MS/MS provides a faster and more comprehensive lipid profile of Dictyostelium discoideum cells and has the potential to be further applied to other biological problems. Over 100 lipids have been identified from a wide variety of lipid classes (e.g., phosphoglycerols and ceramides) and levels of expression. Challenges and future trends are discussed for the development of discovery and targeted monitoring strategies using TIMS-MS/MS and LC-TIMS-MS/MS.
UNRAVELING THE STRUCTURAL COMPLEXITY OF CRUDE OILS USING TIMS-FT-ICR MS
Paolo Benigni1, Francisco Fernandez-Lima1,2
1Department of Chemistry and Biochemistry, Florida International University, Miami, USA
2Biomolecular Sciences Institute, Florida International University, Miami, USA
Crude oil is one of the most complex mixtures in the world, with over 100,000 estimated number of unique molecular components. Characterization of a crude oil is particularly difficult because current analytical techniques are only able to identify a small fraction of the molecular components in a crude oil. Therefore, our knowledge of crude oil, at the molecular level, has been limited to the molecular species that can be separated by Gas Chromatography MS; However, this greatly limits the molecular species that can be analyzed, primarily due to the volatility requirements of the GC separation. In this work, for the first time, Trapped Ion Mobility Spectrometry is coupled to FT-ICR MS for the analysis of standard crude oils. When utilizing TIMS-FT-ICR MS we are able to separate isomeric molecular species using high resolution ion mobility spectrometry (R>150). These two dimensions of analysis increases the peak capacity, allowing for a greater number of identifications compared to MS alone. Another advantage of TIMS is that is it a time independent separation, therefore the FT-ICR MS analysis step does not have to be reduced in order to have an analytical number of points characterizing the peak. An unsupervised candidature structure workflow was developed to proposed candidate structures based on their chemical formula and mobility measurements.
Influence of the bath Gas on the mobility separation and stability of common explosives
Alan McKenzie-Coe1, Francisco Fernandez-Lima1,2
1 Department of Chemistry and Biochemistry, Florida International University, Miami, USA
2 Biomolecular Science Institute, Florida International University, Miami, USA
In a previous work, we showed the potential of Trapped Ion Mobility Spectrometry Mass Spectrometry for the separation and characterization of common explosives in air. In particular, we showed that adduct complexes of explosives can undergo exponential losses in their ion abundance due to interactions with the residual gas molecules. In the present work, a systematic study was performed in other to evaluate the stability and reactivity of common explosives as a function of the bath gas composition. Theoretical calculations were performed to study the effect of residual gas molecules on the reaction landscape of the explosive complexes. In addition, dopant gases were introduced to TIMS-MS operation to tailor the interactions using methanol, 2-propanol, and acetone as gas modifiers. Preliminary results show that gas modifiers can significantly affect the separation and mobility of common explosive complexes during a TIMS-MS experiment.
Predicting and refining crystal structures with NMR data
James Harper, Keyton Kalakewich, Luther Wang
University of Central Florida, Department of Chemistry
Theoretical crystal structure predictions (CSP) usually ranks candidates by lattice energy. Despite significant recent progress, the consistent selection of a correct structure remains challenging and is largely limited to rigid structures. This presentation explores an alternative in which NMR parameters are calculated for candidate structures then compared with experimental data to obtain rankings. This approach is demonstrated to eliminate approximately 90% of CSP candidates when carbon-13 data are employed and lattice effects are ignored. Inclusion of lattice fields significantly improves selectivity and allows a single correct structure to be consistently chosen. An important component of these studies is the discovery that an ab initio refinement of geometry is required in to ensure accurately selection. Surprisingly, most published crystal structures can also be improved by a lattice-including refinement. Several NMR parameters are able to track and guide these refinements, but they are largely undetectable by conventional diffraction methods. This “NMR crystallography” approach to refining and improving certain crystal structures is illustrated using lauric acid and other small organic structures. Harper, J. K. and Grant, D. M. (2006). Cryst. Growth Des., 6, 2315–2321.  Kalakewich, K. et al.(2013) Cryst. Growth Des. 13, 5391–5396.  Harper, J. K. et al. (2013) CrystEngComm, 15, 8693–8704.