Effects of matrix-assisted laser desorption/ionization experimental conditions on quantitative compositional analysis of ethylene oxide/propylene oxide copolymers

Abstract

Matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry has the potential to become a valuable tool for the compositional analysis of copolymers. For a copolymer composed of structurally very similar building blocks with minor chain length changes, one would expect the relative peak intensities observed in the MALDI mass spectra to reflect its composition, at least within a narrow mass range. However, we show that variations in experimental conditions in MALDI can have a significant effect on the mass spectral appearance of a copolymer. The effects of concentration, laser power, type of matrices and solvents on mass spectra of an ethylene oxide/propylene oxide copolymer are illustrated. These somewhat surprising results show that great care needs to be exercised when interpreting copolymer spectra for compositional analysis, even for copolymers with structurally similar monomers. This work also points out that further studies are needed to better understand and optimize spectral acquisition conditions for reliable copolymer compositional analysis by MALDI. Copyright © 2000 John Wiley & Sons, Ltd.

Compositional analysis of isobutylene/p-methylstyrene copolymers by matrix-assisted laser desorption/ionization mass spectrometry

“…Wilczek-Vera and coworkers found similar skewing with respect to styrene content with ␣-methylstyrene/4-vinylpyridine copolymers [10]. Even with the structurally similar ethylene oxide/ propylene oxide monomers, compositional biases have been observed in copolymer spectra, even though homopolymers of both are easy to ionize [11]. It is reasonable to assume that the MALDI analysis of other copolymers where monomers are even more structurally different would similarly suffer.…”

Quantitative analysis of technical polymer mixtures by matrix assisted laser desorption/ionization time of flight mass spectrometry

“…Preliminary aspects of molecular weight analysis by MALDI have been explored [23]. MALDI experimental parameters can also affect the appearance of a copolymer mass distribution and skew MALDI compositional analysis according to monomers used in copolymer synthesis [24]. A series of samples were prepared containing the same amount of PMMA and different amounts of PDMS, listed in Table 1.…”

Applications of MALDI-TOF-MS in structural characterization of synthetic polymers

“…5 Moreover, the types of matrices used in the experiments can affect the relative intensities of synthetic oligomers. 19,20 For example, three matrices 2,5-dihydroxy benzoic acid (DHB), dithranol (DIT) and α-cyano-4-hydroxycinnamic acid (CHCA) were compared to characterize various polymers by Cho and his coworkers. The advantage of DIT over CHCA and 2,5-DHB is compared in Fig.…”