Final LDRD report : development of sample preparation methods for ChIPMA-based imaging mass spectrometry of tissue samples.

The objective of this short-term LDRD project was to acquire the tools needed to use our chemical imaging precision mass analyzer (ChIPMA) instrument to analyze tissue samples. This effort was an outgrowth of discussions with oncologists on the need to find the cellular origin of signals in mass spectra of serum samples, which provide biomarkers for ovarian cancer. The ultimate goal would be to collect chemical images of biopsy samples allowing the chemical images of diseased and nondiseased sections of a sample to be compared. The equipment needed to prepare tissue samples have been acquired and built. This equipment includes an cyro-ultramicrotome for preparing thin sections of samples and a coating unit. The coating unit uses an electrospray system to deposit small droplets of a UV-photo absorbing compound on the surface of the tissue samples. Both units are operational. The tissue sample must be coated with the organic compound to enable matrix assisted laser desorption/ionization (MALDI) and matrix enhanced secondary ion mass spectrometry (ME-SIMS) measurements with the ChIPMA instrument Initial plans to test the sample preparation using human tissue samples required development of administrative procedures beyond the scope of this LDRD. Hence, it was decided to make two types of measurements: (1) Testing the spatial resolution of ME-SIMS by preparing a substrate coated with a mixture of an organic matrix and a bio standard and etching a defined pattern in the coating using a liquid metal ion beam, and (2) preparing and imaging C. elegans worms. Difficulties arose in sectioning the C. elegans for analysis and funds and time to overcome these difficulties were not available in this project. The facilities are now available for preparing biological samples for analysis with the ChIPMA instrument. Some further investment of time and resources in sample preparation should make this a useful tool for chemical imaging applications

Synthesis, structural characterization, and thermal decomposition study of Mg(H2O)6B10H10·4H2O

Compound 1 (Mg(H2O)6B10H10 3 4H2O) was synthesized and characterized using NMR, IR, XRD, and elemental analysis. Its thermal decomposition behavior was studied using Simultaneous Thermogravimetric Modulated Beam Mass Spectrometry (STMBMS), TGA, DSC, IR, and 11B NMR. The crystal structure of 1 reveals multiple dihydrogen and hydrogen bonding interactions that form a 3D extended structure. A reaction network characterizing the thermal decomposition of 1 and its secondary products over a temperature range from 20 to 1000 _C has been developed. Thermal decomposition of 1 is primarily controlled by two competing branches in the reaction network, where coordinated water evolves as either H2O (dehydration) or H2 (dehydrogenation). The extent of reaction to form H2 depends on the fraction of the coordinated water remaining in the sample when its temperature is between 160 and 225 _C. The evolution of coordinated water is reversible and controlled by dissociative sublimation. For the release of coordinated water between 160 and 215 _C, the vapor pressure of water is given by Loge P (Torr) = 30.4561 _ 12425.2/T (K) and ΔHs = 103.3(0.3 kJ/mol. The nature of the condensed phase secondary product remaining after all coordinated water is removed by either dehydration and/or dehydrogenation depends strongly on the extent of reaction to form Mg(OH)xB10H10_x. Results of STMBMS experiments where x varies from 0.2 to ∼4 are used to develop the reaction network that characterizes the thermal decomposition process. Heating of 1 at 205 _C resulted in the formation of water-soluble Mg(OH)x(H2O)2_xB10H10_x, while prolonged heating of 1 at 270 _C and heating up to 1000 _C led to decompositio

The structural characterization of (NH4)2B10H10 and thermal decomposition studies of (NH4)2B10H10 and (NH4)2B12H12

The structure of (NH4)2B10H10 (1) was determined through powder XRD analysis. The thermal decomposition of 1 and (NH4)2B12H12 (2) was examined between 20 and 1000oC using STMBMS methods. Between 200 and 400oC a mixture of NH3 and H2 evolves from both compounds; above 400oC only H2 evolves. The dihydrogen bonding interaction in 1 is much stronger than that in 2. The stronger dihydrogen bond in 1 resulted in a significant reduction by up to 60oC, but with a corresponding 25% decrease in the yield of H2 in the lower temperature region and a doubling of the yield of NH3. The decomposition of 1 follows a lower temperature exothermic reaction pathway that yields substantially more NH3 than the higher temperature endothermic pathway of 2. Heating of 1 at 250oC resulted in partial conversion of B10H102 to B12H122 Both 1 and 2 form an insoluble polymeric material after decomposition. The elements of the reaction network that control the release of H2 from the B10H102 can be altered by conducting the experiment under conditions in whichpressures of NH3 and H2 are either near, or away from, their equilibrium values