Authors:Beate Fuchs, Jürgen Schiller, Rosmarie Süß, Ariane Nimptsch, Martin Schürenberg, and Detlev Suckau
Lipids are important natural products and essential in nutrition, cosmetic formulations, pharmaceuticals, etc. Lipids and, particularly, phospholipids are of substantial medical interest (some are molecules with messenger function) and of diagnostic potential (for instance, the lipoproteins in human blood). Among the different soft-ionization mass spectrometric methods that enable detection of the intact lipid molecules, matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has several advantages, for instance, simple performance, high sensitivity, and robustness against contaminants. Additionally, MALDI-TOF MS analyzes a solid sample. This enables (in contrast with isotropic solutions) acquisition of spatially-resolved mass spectra (‘mass spectrometric imaging’). However, separation of complex mixtures into the individual lipid classes is normally required to enable detection of all the components. It will be shown with the example of a lipid extract from hens’ egg yolk that MALDI-TOF MS can be easily combined with TLC, enabling detection of as little as picomole amounts of lipids directly on the HPTLC plate. This results in sensitivities higher than those from established staining procedures. Additionally, because of the substantial spatial resolution, lipids separated by normal-phase TLC may not only be differentiated according to differences of their headgroups but also according to differences of their fatty acyl composition. Finally, MS-MS experiments, providing further insights into the structures of the relevant lipids, can be also performed directly on the HPTLC plate. Although the HPTLC-MALDI coupling can be easily established, there are different points to which special attention should be paid. Aspects of matrix application, data acquisition (including the stability of lipids and reproducibility), and data evaluation will be emphasized in this paper
Laser desorption ionization (LDI) mode of matrix-assisted laser desorptionionization time-of-flight mass spectrometry (MALDI-TOFMS) analysis of uranium(VI)leads to the formation of uranium oxides clusters, as with fast atom bombardment(FAB). Different uranium clusters than those with FAB were observed. Threedifferent families of formula (UO2)x Oy2+, and two of formula (UO2)x Oy2+ were found.
Authors:N. Dragoe, K. Nakahara, L. Xiao, H. Shimotani, and K. Kitazawa
The thermal decomposition of methano-fullerene derivatives such as ethoxycarbonyl methano fullerene and various isomers
of bis-(ethoxycarbonyl methano) fullerene leads to new fullerene derivatives, which have been preliminary characterized.
The analysis of separated species was performed by UV-VIS, IR, H- and C-NMR, STM, FAB, LDI and MALDI-TOF MS spectroscopy.
One of the isolated phases is a C122 molecule with a dumbbell-like structure.
Authors:J.A. Campbell, W.P. Hess, J.R. Lohman, and S.C. Goheen
Matrix-assisted laser desorption/ionization coupled with time-of-flight mass spectrometry (MALDI/TOF-MS) was used for the analysis of low-molecular phosphate compounds found in Hanford tank wastes. The mass spectra of these compounds indicate protonated peaks as well as sodium adducts. Analytical methods presently utilized for the analysis of the phosphate-related organics are both time consuming and labor intensive. A promising alternative is MALDI/TOFMS. The MALDI process produces both positive and negative ions directly and very little sample is required. In addition, there is limited sample preparation and minimal hazardous waste production.
Authors:A. Bischoff, M. Eibisch, B. Fuchs, R. Süss, M. Schürenberg, D. Suckau, and J. Schiller
The analysis of lipid-phospholipid oxidation products is of primary importance. Although there are established HPLC and LC-MS techniques, it is shown here for the first time that the combination of matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) and TLC represents a sensitive, fast, and convenient alternative. A mixture of 1-palmitoyl-2-linoleoyl-sn-phosphatidylcholine (PLPC) and -ethanolamine (PLPE) was oxidized under the influence of atmospheric oxygen and characterized by direct positive ion MALDI-TOF MS as well as combined TLC-MALDI. It is shown that much more detailed information — particularly related to the oxidation products of PLPE that have so far been scarcely investigated — can be obtained by TLC-MALDI. However, it is also shown that further methodological improvements are necessary to make this method generally applicable to complex lipid mixtures.
Authors:Hui-Zhou Gao, Qi Yang, Xiao-Yan Yan, Zhu-Jun Wang, Ji-Li Feng, Xia Yang, Sheng-Li Gao, Lei Feng, Xu Cheng, Chao Jia, and Ke-Wu Yang
previously [ 12 ]. The L1 purity was identified by SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis), and confirmed by MALDI-TOF (matrix-assisted laser desorption ionization, time-of-flight) mass spectrum. The calorimetric experiments at
Authors:Wenwen Huang, Sreevidhya Krishnaji, David Kaplan, and Peggy Cebe
purity. MALDI-TOF was used to confirm protein identity. The materials were obtained in solid form after lyophilizing and then cast into films from water solution for the purpose of our studies. The number of residues, the amino acid sequences, and the