Enhanced Cationization of Polymers Using Delayed Ion Extraction with Matrix-assisted Laser Desorption/Ionization

Cation attachment during matrix-assisted laser desorption/ionization (MALDI) of various synthetic polymers was investigated. The ions were created in a field-free source and extracted by a pulsed electric field applied at a known and variable time delay after the laser pulse. This is shown to increase the magnitude of the cationized polymer signal obtained, and also allows higher laser intensities to be used to induce fragmentation in the polymer. Additional structural information is thus provided about the monomers and end groups that is not available from measurements solely of the mass distribution of the intact cationized polymer. Delayed extraction can also provide important information about the timescale of the cation attachment processes occurring during MALDI.