Liquid atmospheric pressure MALDI (LAP‐MALDI) mass spectrometry: a versatile tool for the characterization of synthetic polymers

Kowalczyk, A. E., Brown, J., Morris, M. and Cramer, R. ORCID: https://orcid.org/0000-0002-8037-2511 (2026) Liquid atmospheric pressure MALDI (LAP‐MALDI) mass spectrometry: a versatile tool for the characterization of synthetic polymers. Rapid Communications in Mass Spectrometry, 40 (16). e70102. ISSN 1097-0231 doi: 10.1002/rcm.70102

Abstract/Summary

RATIONALE: Liquid atmospheric pressure matrix-assisted laser desorption/ionization (LAP-MALDI) mass spectrometry (MS) has previously been applied to the analysis of biopolymers such as peptides, proteins and DNA, producing ESI-like multiply charged analyte ions. In this study, LAP-MALDI MS has been investigated for the analysis of synthetic polymers for the first time. METHODS: A LAP-MALDI source was interfaced with a Q-TOF mass spectrometer. The study investigated synthetic polymer standards including polyethylene glycol (PEG), polypropylene glycol (PPG), polyacrylic acid (PAA), and polystyrene (PS) of different sizes in positive and negative ionization modes with and without ion mobility spectrometry (IMS). The acquired data were compared to ESI MS data using the same polymer standards and instrument but with a standard ESI source. RESULTS: LAP-MALDI MS enables the detection of singly and predominantly multiply charged ions with high ion signal stability (<10% RSD), though with lower charge states than ESI MS. Its flexible sample preparation and ion source setup allows for the controlled manipulation of charge states. Common salts facilitate ionization by metal cation adduct formation and improve detection of PEG, PPG and PS. PAA was efficiently detected in negative ion mode by deprotonation, and PS required a silver salt for ionization. IMS provides an additional dimension in separation and manipulating charge state distributions, and its data obtained for PEG corroborate previously published ESI IMS results. CONCLUSIONS: LAP-MALDI MS provides a rapid, less labor-intensive, and reagent-efficient way for the analysis of synthetic polymers and produces stable ion signals in both positive and negative ion modes. The source enables the detection of singly and multiply charged ions, with the flexibility to manipulate charge states over a wide range. LAP-MALDI MS tolerates diverse solvent compositions and offers a versatile platform for high-throughput polymer structural analysis, including MS/MS analysis, that can replace or complement standard polymer analysis tools.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/129786
Identification Number/DOI	10.1002/rcm.70102
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
Publisher	Wiley
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