1. ABOUT THE DATASET ------------ Title: Dataset supporting 'LAP-MALDI MS: A Versatile Tool for the Characterization of Synthetic Polymers' Creator(s): Agata E. Kowalczyk (https://orcid.org/0009-0009-6810-8644) and Rainer Cramer (https://orcid.org/0000-0002-8037-2511) Organisation(s): University of Reading Rights-holder(s): University of Reading Publication Year: 2026 Description: This dataset includes raw and processed data demonstrating the use of liquid atmospheric-pressure matrix-assisted laser desorption/ionisation (LAP-MALDI) mass spectrometry (MS) and MS/MS for the analysis of synthetic polymers. The data was acquired as a part of the PhD project 'Novel applications of LAP-MALDI MS' and compared to data obtained with a standard ESI source on the same mass spectrometer, i.e. a Waters SYNAPT(TM) G2-Si mass spectrometer with a commercial (Waters) ESI source and with a LAP-MALDI source as previously reported (Ryumin, P. et al. Methods 2016, 104, 11-20). Commercially sourced polymers (PEG, PPG, PS, PAA) were prepared in suitable solvents (water, acetonitrile, THF, DMSO) with and without the addition of metal chloride, iodide and acetate salts as well as 3-NBA at different concentrations, leading to different average charge states. PEG, PPG and PS were analysed in positive ion mode, and PAA in negative ion mode. Different ion transfer tube temperatures and cone voltages were also investigated, and shifts in the detection of the different polymer chains were recorded with the associated shifts in calculated Mn and Mw values. LAP-MALDI samples were analysed using a CHCA, HABA, DHB and dithranol-based liquid matrix formulations stabilised with propylene glycol. Stable polymer ion signals (TICs within ~10% RSD) were obtained. Changelog: N/A Cite as: Kowalczyk, A.E. and Cramer, R. (2026): Dataset supporting 'LAP-MALDI MS: A Versatile Tool for the Characterization of Synthetic Polymers'. University of Reading. Dataset.https://doi.org/10.17864/1947.001488 Related publication: Agata E. Kowalczyk, Jeffery Brown, Michael Morris and Rainer Cramer (2026): 'Liquid Atmospheric Pressure MALDI (LAP-MALDI) Mass Spectrometry: A Versatile Tool for the Characterization of Synthetic Polymers'. Submitted for publication to Macromolecules. Contributors: Jeffery Brown and Michael Morris (Waters Corporation) Contact: Prof. Rainer Cramer, Department of Chemistry, University of Reading, Reading RG6 6DX, United Kingdom, Tel: 0118 378 4550, Email: r.k.cramer@reading.ac.uk 2. TERMS OF USE ------------ Copyright 2026 University of Reading. This dataset is licensed under a Creative Commons Attribution 4.0 International Licence: https://creativecommons.org/licenses/by/4.0/. 3. PROJECT AND FUNDING INFORMATION ------------ Title: Novel applications of LAP-MALDI MS Dates: 2023-2026 Funding organisation: This dataset relates to a funded PhD project sponsored by Micromass (Waters Corporation) and the University of Reading. 4. CONTENTS ------------ File listing: 'RawData_10Feb2026' contains all raw ESI and LAP-MALDI MS and MS/MS data. Files are named starting with the acquisition date (YYYY/MM/DD), followed by the initials of the operator (AK), source type (ESI, LAPMALDI), the polymer names (PAA, PEG3000, PPG2700, PPG4000, PS), the matrix chromophore (where applicable) and any additional information such as additives, instrument parameter changes or the data acquisition mode (e.g. MS, MSMS, POS = positive ion mode, NEG = negative ion mode, TT = transfer tube, 1P = 1%, 20P = 20%, BLANK = 0%, 3SPOTS = data acquired from 3 spot replicates). The '20250423_AK_LAPMALDI_PEG3000_DHB_COMBINEDADDUCTS_MS_POS' file contains data acquisitions from 5 samples with LiCl (scans ~81-100), NaCl (scans ~21-40), KCl (scans 41-60), CsI (scans ~1-20) and AgTFA (scans ~61-80) salt additions, respectively. The '20250620_AK_LAPMALDI_PAA_HABA_CONEBIAS_MS_NEG' file contains data acquisitions from a sample using increasing cone voltages, i.e. 10 V (scans ~1-15), 50 V (scans ~16-30), 100 V (scans 31-50) and 150 V (scans 51-70), as well as 200 V and data acquisitions using decreasing cone voltages, respectively. 5. METHODS ----------- The dataset contains data that was generated using a commercial mass spectrometer SYNAPT(TM) G2-Si HDMS (Waters) equipped with an in-house developed AP-MALDI and a commercial ESI source. MassLynx(TM) software (ver. 4.2; Waters) was used to collect and process the data, and further processing was carried out using Origin 2024b, UniDec, and MSPolyCalc as per the methods section in the related publication, which also contains further information on the methods and subsequent data processing.