JMSSJ On-line, Vol. 55 (2007) No. 5, pp. 343-351
Charge-Remote Fragmentation of Phospholipids in a Multi-Turn Tandem Time-of-Flight Mass Spectrometer “MULTUM-TOF/TOF”
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    Shuichi SHIMMA,1* Hirofumi NAGAO,2 and Michisato TOYODA1

    1 Department of Physics, Graduate School of Science, Osaka University, Toyonaka, OSAKA, JAPAN
    2 Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka Univeristy, Suita, OSAKA, JAPAN

High-energy collision-induced dissociation (CID) provides characteristic structural information about interested molecules, which cannot be obtained by low energy CID. High-energy CID is available using magnetic sector or time-of-flight (TOF) type mass spectrometers. In our laboratory, a multi-turn tandem TOF mass spectrometer (MULTUM-TOF/TOF) has been developed that has a multi-turn TOF mass spectrometer (MULTUM) as the first stage and a quadratic-field ion mirror as the second stage. MULTUM-TOF/TOF enables obtaining high-energy CID spectra with high resolving power for precursor ion selection. Furthermore, the signal-to-noise (S/N) ratio of the product ion mass spectrum is dramatically improved by increasing the number of cycles, because fragment ions caused by post-source decay are eliminated. The improved S/N ratio facilitates the recognition of signal peaks that have low intensity. In this paper, we performed the structural analysis of lysophosphatidylcholine (LPC) (18 : 1) using MULTUM-TOF/TOF. We obtained ions derived not only from a dissociation of the polar headgroup but also from charge-remote fragmentation generated by a high-energy CID process. Here, charge-remote fragmentation is the cleavage of a long-chain alkyl in a fatty acid moiety. Therefore, the position of the double bonds was successfully determined. The characteristics of product ion mass spectra obtained from sodiated and protonated LPC were also investigated.

Key words: Charge-remote fragmentation, Multi-turn time-of-flight, Quadratic-field ion mirror, High energy CID, Lysophosphatidylcholine

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