Previously a new method was introduced for the mass spectrometry of saturated polyolefins Whereby an organic cation is covalently bonded to the polymer to produce the necessary ionization for the creation of intact gas-phase macromolecules by matrix-assisted laser desorption/ionization (MALDI).(1) In the present study that methodology was further optimized to produce mass spectra for higher molecular mass materials than had been achieved previously. NIST Standard Reference Material polyethylenes were extensively studied and found to give molecular masses that were systematically low, typically about two-thirds of the values determined classically. However, when comparison was made between conventional copper metal cationization of end-functionalized polybutadiene and the same material hydrogenated and subsequently covalently cationized, excellent agreement was found when the molecular mass distributions of these two materials were compared. Reasons for this discrepancy are explored and discussed.