Tandem Mass Spectrometry for Polymeric Structure Analysis: A Comparison of Two Common MALDI–ToF/ToF Techniques

Abstract

Tandem mass spectrometry is a powerful technique for investigating polymer architecture. However, in‐depth studies of the technique for polymers is relatively lacking when compared to other areas of mass spectrometry (MS). This paper examines the use laser‐induced dissociation and collision‐induced dissociation (CID) in MALDI–LIFT–ToF/ToF experiments to compare the usage of the two techniques on a range of polymeric analytes. It is demonstrated that for samples with an energetically preferable fragmentation pathway, such as those with a functional group in the backbone or a labile end group, post source decay (PSD) provides a simplified spectra with an increased pathway selectivity due to its utilization of metastable decay. This makes PSD a preferable technique for polymer sequencing, especially in low‐resolution time‐of‐flight techniques. Conversely, CID fragments less selectively, leading to higher intensity peaks from less favorable fragmentations. This makes CID more preferred for exact structural determination, such as finding the repeat unit structure.

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“…To verify the ω-Br functionality of the obtained polymers, matrix assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-ToF-MS) was employed for pMA 20 . 43,44 A single peak distribution corresponding to bromine-capped polymer chains was found, indicating the retention of the ω-end ( Fig. 2a & b) with a calculated mass for bromine terminated polymer with DP n = 25 of 2369.9 Da and an observed mass = 2370.2 Da with the associated isotopic pattern expected for incorporation of bromine, confirming the structure as shown in Fig.…”

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“…Application of the MALDI TOF/TOF allowed for observation of further fragmentation of the molecular ions. This technique successfully identifies macromolecular compounds such as proteins, peptides, DNA, and polymers [ 45 , 46 , 47 ]. Exemplary mass spectra of compound 3 are shown in Figure S33 , with masses noted for the most abundant ions.…”

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“…The path of decomposition generated in the ionization process quasimolecular ions [M+H] + of new octa- and tetrasubstituted Pcs was studied. For this task the MALDI-LIFT-TOF technique was chosen, which was used successfully in the identification of macromolecular compounds such as proteins, peptides DNA and polymers [ 40 , 41 , 42 ]. Scheme 2 A presents the observed fragmentation of parent ions [M+H] + .…”