Atmospheric pressure matrix-assisted laser desorption/ionisation ion trap mass spectrometry of synthetic polymers: A comparison with vacuum MALDI-TOF

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Eur. J. Mass Spectrom. DOI: 10.1255/ejms.528

Atmospheric pressure matrix-assisted laser desorption/ionisation ion trap mass spectrometry of synthetic polymers: A comparison with vacuum MALDI-TOF

Colin S. Creaser^* and James C. Reynolds
School of Science, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK
William F. Nichols
Eastman Kodak Company, 1999 Lake Avenue, Rochester, NY 14650, USA
Andrew J. Hoteling
Eastman Kodak Company, 1999 Lake Avenue, Rochester, NY 14650, USA and Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA
Kevin G. Owens
Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA

ABSTRACT:

Atmospheric pressure matrix-assisted laser desorption/ionisation quadrupole ion trap mass spectrometry (AP-MALDI/QIT) has been investigated for the analysis of polyethylene glycol (PEG 1500) and a hyperbranched polymer (polyglycidol) in the presence of alkali metal salts. MS spectra of PEG-1500 obtained at atmospheric pressure showed dimetallated matrix/analyte adducts, in addition to the expected alkali metal/PEG ions, for all matrix/alkali metal salt combinations. The relative intensities of the desorbed ions were dependent on the matrix, the alkali metal salt added to aid cationization and the ion trap interface conditions (capillary temperature, in-source CID). These data indicate that the adducts are rapidly stabilised by collisional cooling enabling them to be transferred into the ion trap. Experiments using identical sample preparation conditions were carried out on a vacuum MALDI time-of-flight mass spectrometer. In all cases, vacuum MALDI-TOF spectra showed only alkali metal/PEG ions and no matrix/analyte adducts. The MS/MS capability of the ion trap has been demonstrated for a lithiated polyglycol yielding a rich fragment ion spectrum. Analysis of the hyperbranched polymer polyglycidol by AP-MALDI/QIT reveals the characteristic ion series for these polymers also observed under vacuum MALDI-TOF conditions.

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