Characterisation of electrosprayed polymers with MALDI-FT-ICR-MS

The combination of an ionisation technique like Matrix Assisted Laser Desorption Ionisation (MALDI) with mass spectrometry has already proven to be a valuable technique to characterise the molecular weight distribution and the dispersity of synthetic polymers. In this paper we have used the unequivocally high resolution of Fourier Transform Ion Cyclotron Mass Spectrometry (FT-ICR-MS) to additionally identify the elemental composition of the monomer and endgroup of several (homo) polymers. The information thus obtained provides insight in both initiation and termination of the polymerisation reaction cycle, as parts of the reactants are found back as structural components in the end-groups. In all experiments, MALDI performed in a homebuild external ion source was used as ionisation technique. Sample preparation turned out to be critical for the succes of this method. In the following sections we will discuss a new sample preparation method which we found to yield very strong and reproducable MALDI-FT-ICR-MS signals of polymeric compounds.