Polymer molecular weight distribution: Results from matrix‐assisted laser desorption ionization compared with those from gel‐permeation chromatography

A sample of poly(methyl methacrylate) (PMMA), of which the molecular weight was known from light‐scattering measurements, was subjected to gel‐perrneation‐chromatographic analysis, and the resulting Weight versus log molecular weight (MW) plot was converted by suitable computation to a Number versus linear MW plot. This could then be compared directly with the matrix‐assisted laser desorption ionization MW distribution results obtained for the same sample. The MW distributions obtained by the two methods were significantly different. Two explanations for the discrepancy are offered.