Mining the NIST Mass Spectral Library Reveals the Extent of Sodium Assisted Inductive Cleavage in Collision-Induced Fragmentation

Interpretation and annotation of fragmentation mass spectra strongly depends on our knowledge of collision-induced fragmentation mechanisms. Computational methods for interpretation of fragmentation operate in the boundaries of recognized fragmentation rules. The prevalence of non-sodiated fragment ions in sodiated ion fragmentation spectra is not yet fully recognized by the mass spectrometry community. Here, we investigated the extent of “Sodium Assisted Inductive Cleavage” (SAIC), a charge migration fragmentation occurring in the fragmentation spectra of sodiated precursors. The NIST17 fragmentation library was mined for evidence of SAIC. A substantial amount of fragment ions in sodiated precursor spectra can be linked to SAIC. Thus, this fragmentation mechanism must be considered to allow for accurate interpretation of fragmentation spectra.