Updating evidence for cationization of polymers in the gas phase during matrix-assisted laser desorption/ionization

Eur. J. Mass Spectrom. 11, 23–30 (2005)
DOI: 10.1255/ejms.715

Updating evidence for cationization of polymers in the gas phase during matrix-assisted laser desorption/ionization

Scott D. Hanton,^a,* Kevin G. Owens,^b Cynthia Chavez-Eng^b,d Anne-Mette Hoberg^c,e and Peter J. Derrick^c
^aAir Products and Chemicals, Inc. Allentown, PA USA 18195, USA. Email: hantonsd@apci.com
^bDepartment of Chemistry, Drexel University, Philadelphia, PA 19104, USA
^cInstitute of Mass Spectrometry and Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK

ABSTRACT:

Matrix-assisted laser desorption/ionization (MALDI) techniques have been developed to determine the chemical structure of a variety of industrial polymers. Despite the enormous popularity and power of MALDI, the details of the cationization mechanisms of the process are currently rather poorly understood. The MALDI cationization of polymer analytes was investigated previously by Hoberg and co-workers.1 They used layered samples to explore the role of gas-phase cationization in MALDI of polymers. This paper seeks to extend the work initiated by Hoberg and co-workers and update the results of the earlier work. The new experiments take advantage of a MALDI instrument with delayed extraction and show that separation in the initial acceleration region of the mass spectrometer is not a key component of cationization. Investigations of tri-layer samples by time-of-flight secondary ion mass spectrometry (ToF-SIMS) also show that there is considerable interaction among the layers. These interactions, specifically the solubility of the salts in the solvents, account for the presence of the bottom layer cation in the mass spectra. The absence of the top layer cation in the mass spectra is due to the inability of the polymer oligomers to penetrate that layer during desorption.

Keywords: matrix-assisted laser desorption, MALDI, time-of-flight mass spectrometry, gas-phase cationization, time-of-flight secondary ion mass spectrometry, ToF-SIMS, polymer, electrospray deposition

You can buy this paper on-line in PDF format; it costs only £11.75. Just click on the BUY on-line button. You can pay on-line through a secure server and get access immediately.