Hydrogen-deuterium exchange in time-of-flight secondary ion mass spectra of polystyrene

A mixture of perdeuterio-(DPS) and perhydro-(HPS) polystyrene was examined by time-of-flight secondary ion mass spectrometry to determine whether hydrogen/deuterium exchange would occur between the two polymers during the SIMS ion emission process. Examination of the spectra showed that no observable hydrogen/deuterium exchange occurred for small polystyrene fragments (less than 500 Da), main-chain fragments (800-3000 Da), or oligomers. A variety of data analysis procedures, including correlation techniques, linear least squares regression analysis, principal component analysis, and spectral reconstruction (triple H) were used to examine the differences between the individual HPS and DPS components and the mixtures. No significant differences between the individual components and the mixtures were determined using any of the data analysis procedures. Thus, polymer fragmentation in TOF-SIMS, which involves H transfer, must occur vis intramolecular rather than intermolecular mechanisms.