The observation of broad metastable ion peaks in the surface-induced dissociation mass spectra of protonated and cationated peptides

The product ion mass spectra of protonated and cationated peptides of relative molecular mass (RMM) 555–574 Da have been obtained by surface-induced dissociation of MH⁺ and [M + Cat]⁻ ions in a four-sector tandem mass spectrometer equipped with a specially designed collision cell. A linked scan of the electric and magnetic sector field strengths of the second mass spectrometer was used to transmit the fragment ions arising from collisions with a stainless steel surface. The resulting mass spectra contained broad metastable ion peaks produced by the dissociation of MH⁺ and [M + Cat]⁺ ions before the second magnetic sector, in the fourth field-free region of the instrument.