FAQ: How often does hydrogen-shift rearrangement occur?

High charge states can lead to hydrogen-shift rearrangement resulting in loss of the double bond with the addition of two hydrogens. This may only occur in certain mass spectrometers. We saw this occurrence in the ion trap MS (the [M-4H]4- ion has an observed value of 382.74; the theoretical value after hydrogen-shift rearrangement is 382.75); however we did not see hydrogen-shift analysis in the TOF MS.