Chemical Composition and Topology of Poly(lactide‐co‐glycolide) Revealed by Pushing MALDI‐TOF MS to Its Limit

Abstract

Software developed in house in combination with a recently developed method of MALDI‐TOF MS enable not only the elucidation of individual chain structures of poly(lactide‐co‐glycolide), a polymer used extensively in the medical sector, but a full characterization of this copolymer including even its chemical composition and topology (random, gradient, block (see figure), or alternating).

COCONUT—An Efficient Tool for Estimating Copolymer Compositions from Mass Spectra

“…The copolymer composition matrix provides information about the copolymer architecture, 12,13 the distribution of block lengths in block copolymers, 11,14−16 or the reactivity ratio of the consumed monomers. 17 It has been used to study degradation 10 and MALDI matrix effects.…”

A second‐generation ionic liquid matrix‐assisted laser desorption/ionization matrix for effective mass spectrometric analysis of biodegradable polymers

“…The matrix structures and molecular weights are listed in Table 2. The five solid compounds used for MALDI matrixes33, 35–44 were: α ‐cyano‐4‐hydroxycinnamic acid (CHCA), trans ‐3‐indoleacrylic acid (IAA), 2,5‐dihydroxybenzoic acid (DHB), 2‐(4‐hydroxyphenylazo)benzoic acid (HABA), and trans ‐2‐[3‐(4‐tert‐butylphenyl)‐2‐methyl‐2‐propenylidene]malononitrile, also called 1,1‐dicyano‐4‐(4′‐tert‐butylphenyl)‐3‐methyl‐buta‐1,3‐diene (DCTB). The two new ILMs were N , N ‐diisopropylethylammonium α ‐cyano‐4‐hydroxycinnamate (DEA‐CHCA) and N , N ‐diisopropylethylammonium indoleacrylate (DEA‐IAA).…”

“…Size‐exclusion chromatography (SEC) will give a mass range but it can over‐ or underestimate the molecular weight because the standards used are not structurally similar to the unknown polymer 30–32. MALDI‐MS of biodegradable polymers has been studied extensively 33–44. The MALDI‐MS study of these polymers, however, displays intrinsic problems.…”

Abundance correction for mass discrimination effects in polymer mass spectra

“…Fitting a line through the most abundant oligomers before and after correction results in a straight line off center for both which hints at the desired random-like structure. [36] However, due to the sharp slope of the correcting function for larger numbers of PI units, the measured copolymers are less affected in the PI dimension than the non-degraded copolymers would be. Also, there is the possible issue of underestimating PI even after correcting the abundances, due to the differences between the copolymer and homopolymer MALDI matrices, which were necessary to obtain good quality PI mass spectra due to the high mass discrimination in the homopolymer mixtures.…”