A further structural variation of product yield in collisional activation. Study of CH3S+ from dimethyl disulfide with high precursor ion resolution

The isobaric ions CH₃³²S⁺ and CH³⁴S⁺ from dimethyl disulfide were separated and collisionally activated in a four-sector mass spectrometer. The contributions of minor components to the collisional activation spectrum of the unresolved beam are not correctly predicted from consideration of isotope peak corrections using relative intensities of adjacent peaks in the mass spectrum of CH₃SSCH₃, because the isobaric components not only have different cross-sections for fragmentation but also different cross-sections for transmission of the unfragmented beam through the collision gas. Helium collision spectra of the two components are given.