MALDI-TOF MS coupled with collision-induced dissociation (CID) measurements of poly(methyl methacrylate)

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was chosen for an in-detail analysis of poly(methyl methacrylate) (PMMA) in order to determine the possible fragmentation mechanism with the help of collision-induced dissociation (CID). All experiments were performed on a well-defined PMMA standard and were optimized for sample preparation and measurement conditions of both MS and MS/MS. In order to investigate the fragmentation pathways, two parent peaks-both charged with sodium (m/z=1625.9 and 2226.2 Da, respectively)-were selected, thus permitting the examination of possible cleavages, and reaction pathways. For both chosen peaks, the MALDI-TOF MS/MS spectra revealed four fragmentation series that could be explained by single or multiple main chain scissions and secondary reactions of the PMMA side groups. According to the molar mass of the fragments, a loss or migration of the side group to the end of the free radical, followed by a beta-scission, was favored. These insights are the first steps toward the construction of a library with fragments and fragmentation pathways, complementary to proteomics libraries, in order to obtain fast and automated identification of substances.