Analysis of creatine phosphate disodium salt by ESI-MS/MS: A seven-centered rearrangement mechanism in gas phase

Creatine phosphate disodium salt was investigated by electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) both in positive- and negative-ion modes. The results indicate that an unusual seven-centered rearrangement mechanism was involved in the whole fragmentation. The positive product ion at m/z 165 is formed through the seven-centered rearrangement from the precursor ions of [M+Na](+) at m/z 278 and further confirmed by D-labeled experiment and DFT calculation. The negative product ion at m/z 190 resulting from the precursor ion [M-Na](-) at m/z 232 is formed through the seven-centered rearrangement, accompanied with internal residue loss of a methanediimine molecule. In addition, the processes producing the product ion at m/z 97 from [M-2Na+1-1](-) at m/z 210 also involved a seven-centered rearrangement. (C) 2015 Elsevier B.V. All rights reserved.