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Structural characterization of synthetic poly(ester amide) from sebacic acid and 4‐amino‐1‐butanol by matrix‐assisted laser desorption ionization time‐of‐flight/time‐of‐flight tandem mass spectrometry
Author(s) -
Rizzarelli Paola,
Puglisi Concetto
Publication year - 2008
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.3417
Subject(s) - chemistry , sebacic acid , amide , tandem mass spectrometry , mass spectrometry , fragmentation (computing) , bond cleavage , polymer chemistry , organic chemistry , chromatography , computer science , operating system , catalysis
Matrix‐assisted laser desorption/ionization time‐of‐flight/time‐of‐flight tandem mass spectrometry (MALDI‐TOF/TOF‐MS/MS) was employed to analyze a poly(ester amide) sample (PEA‐Bu) from the melt condensation of sebacic acid and 4‐amino‐1‐butanol. In particular, we investigated the fragmentation pathways, the ester/amide bond sequences and the structure of species derived from side reactions during the synthesis. MALDI‐TOF/TOF‐MS/MS analysis was performed on cyclic species and linear oligomers terminated by dicarboxyl groups, carboxyl and hydroxyl groups and diamino alcohol groups. The sodium adducts of these oligomers were selected as precursor ions. Different end groups do not influence the fragmentation of sodiated poly(ester amide) oligomers and similar series of product ions were observed in the MALDI‐TOF/TOF‐MS/MS spectra. According to the structures of the most abundant product ions identified, the main cleavages proceed through a β ‐hydrogen‐transfer rearrangement, leading to the selective scission of the OCH 2 bonds. Abundant product ions originating from CH 2 CH 2 ( β – γ ) bond cleavage in the sebacate moiety were also detected. Their formation should be promoted by the presence of an α , β ‐unsaturated ester or amide end group. MALDI‐TOF/TOF‐MS/MS provided structural information concerning the ester/amide sequences in the polymer chains. In the MALDI‐TOF/TOF‐MS/MS spectra acquired, using argon as the collision gas, of cyclic species and linear oligomers terminated by diamino alcohol groups, product ions in the low‐mass range, undetected in the mass spectra acquired using air as the collision gas, proved to be diagnostic and made it possible to establish the presence of random sequences of ester and amide bonds in the poly(ester amide) sample. Furthermore, MALDI‐TOF/TOF‐MS/MS provided useful information to clarify the structures of precursor ions derived from side reactions during the synthesis. Copyright © 2008 John Wiley & Sons, Ltd.