Matrix glycerol

Leisner, A. Rohlfing, A. Berkenkamp, S. Rohling, U. Dreisewerd, K. HUlenkamp, F. IR-MALDI With the Matrix Glycerol Examination of the Plume Expansion Dynamics for Lasers of Different Pulse Duration. 36. DGMS Jahrestagung 2003, Poster. 

Ionization is achieved through the impact of fast and non-ionized heavy atoms (Ar and Xe) targeting the sample being previously dispersed in a non-volatile liquid matrix (glycerol or diethanolamine) and deposited into the source at the end of a sample probe. 

Figure 1.2 High-speed time-lapse photographs of IR-MALDI plumes generated with an optical parametric oscillator laser with 6-ns pulse width (left panels) and an Er YAC-laser with 100-ns pulse width (right panels). Both lasers were operated at 2.94 4m wavelength. Matrix, glycerol time resolution, 8 ns spatial resolution, 4 im. The top three panels represent gradients of gaseous material density creating gradients...

Polymers for a fatty matrix glycerol behenate, glycerol palmitostearate, waxes, cetyl alcohol... 

The phytotoxin showed a quasi molecular ion at m/z 579 (M -i- H) witfi FAB-MS (matrix glycerol), tiie molecular formula of whidi was deto mined to be C33H55O11 based on the results of high resolution FAB-MS (m/z 5793867, calcd. 579.3897). The UV spectrum of the toxin showed maxima at X 205 and 267 nm. In the H-NMR spectrum (500 MHz, CDCI3), 5 doublet mefliyl, 2 oleHnic or ac l methyl, 1 methoxy m hyl and 6 olefinic proton signals w e observed as characteristic peaks. 

The second electron shuttle system, called the malate-aspartate shuttle, is shown in Figure 21.34. Oxaloacetate is reduced in the cytosol, acquiring the electrons of NADH (which is oxidized to NAD ). Malate is transported across the inner membrane, where it is reoxidized by malate dehydrogenase, converting NAD to NADH in the matrix. This mitochondrial NADH readily enters the electron transport chain. The oxaloacetate produced in this reaction cannot cross the inner membrane and must be transaminated to form aspartate, which can be transported across the membrane to the cytosolic side. Transamination in the cytosol recycles aspartate back to oxaloacetate. In contrast to the glycerol phosphate shuttle, the malate-aspartate cycle is reversible, and it operates as shown in Figure 21.34 only if the NADH/NAD ratio in the cytosol is higher than the ratio in the matrix. Because this shuttle produces NADH in the matrix, the full 2.5 ATPs per NADH are recovered. 

Fast-atom bombardment (FAB) is one of a number of ionization techniques which utilize a matrix material, in which the analyte is dissolved, to transfer sufficient energy to the analyte to facilitate ionization. In FAB, the matrix material is a liquid, such as glycerol, and the energy for ionization is provided by a high-energy atom (usually xenon) or, more recently, an ion (Cs+) beam. In conventional FAB, the solution of analyte in the matrix material is applied to the end of a probe which is placed in the source of the mass spectrometer where it is bombarded with the atom/ion beam. 

The matrix, which in most reported applications appears to be glycerol, may either be incorporated directly into the mobile phase pre-column or added postcolumn. If added to the mobile phase, its effect on the separation must be considered, while if added post-column, significant peak broadening may be observed. 

The correct choice of matrix is fundamental to successful f.a.b.-m.s., and the solubility of the sample in the matrix is a prime consideration. Glycerol (2) is the matrix most commonly used in f.a.b. experiments, and it is ideal... 

FC as sensor molecule has been used to investigate the low-energy mobility, i.e., the nature of the Boson peak and of the trawi-Boson dynamics, of toluene, ethylbenzene, DBF and glycerol glasses [102]. The spectator nucleus Fe is at the center of mass of the sensor molecule FC. In this way, rotations are disregarded and one selects pure translational motions. Thus, the low-energy part of the measured NIS spectra represents the DOS, g(E), of translational motions of the glass matrix (below about 15 meV in Fig. 9.39a). 

FAB has been used to analyse additives in (un) vulcanised elastomer systems [92,94] and FAB matrices have been developed which permit the direct analysis of mixtures of elastomer additives without chromatographic separation. The T-156 triblend vulcanised elastomer additives poly-TMDQ (AO), CTP (retarder), HPPD (antiozonant), and TMTD, OBTS, MBT and A,lV-diisopropyl-2-benzothiazylsulfenamide (accelerators) were studied in three matrix solutions (glycerol, oleic acid, and NPOE) [94]. The thiuram class of accelerators were least successful. Mixture analysis of complex rubber vulcanisates without chromatographic separation was demonstrated. The differentiation of matrix ions from sample ions was enhanced by use of high-resolution acquisition. 

Sample preparation for the common desorption/ionisation (DI) methods varies greatly. Films of solid inorganic or organic samples may be analysed with DI mass spectrometry, but sample preparation as a solution for LSIMS and FAB is far more common. The sample molecules are dissolved in a low-vapour-pressure liquid solvent - usually glycerol or nitrobenzyl alcohol. Other solvents have also been used for more specialised applications. Key requirements for the solvent matrix are sample solubility, low solvent volatility and muted acid - base or redox reactivity. In FAB and LSIMS, the special art of sample preparation in the selection of a solvent matrix, and then manipulation of the mass spectral data afterwards to minimise its contribution, still predominates. Incident particles in FAB and LSIMS are generated in filament ionisation sources or plasma discharge sources. 

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