The molecular mass distribution (MMD) obtained in synthetic polymer characterization by matrix-assisted laser desorption/ionizationtime-of-flight mass spectrometry (MALDI-TOF-MS) may be biased by preferential desorption/ionization of low mass polymer molecules,preferential ion attachment to larger polymers, or degradation and fragmentation due to the desorption process. In this study we focus on theeffect of matrix and laser energy on the MMD of four synthetic polymers of low polydispersity with varying thermal stabilities. The fourpolymers considered were polystyrene (PS), poly(ethylene glycol) (PEG), poly(methyl methacrylate) (PMMA) and poly(tetrahydrofuran)(PTHF). The matrix in which the polymer is analyzed may also influence the laser energy effect of MALDI and was also considered in thispaper. Three common matrixes were considered, dithranol, all trans-retinoic acid (RA) and 2,5-dihydroxybenzoic acid (DHB). Statisticalanalyses of the molecular mass distributions, obtained by varying laser energy and matrixes, reveal trends that can be used to describe theinfluences of matrix and laser energy on MALDI-TOF-MS data measurement of synthetic polymers. The statistical analysis revealed that thematrix has a greater effect on the polymer MMD than was expected. Polymers analyzed in DHB yielded lower mass moments than polymersanalyzed in RA and dithranol. The effects of laser power on the MMD of the polymers were found to be matrix dependent.
Citation: International Journal of Mass Spectrometry
Pub Type: Journals