Characterization of partially transesterified poly(β-hydroxyalkanoate)s using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Abstract

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was used for the characterization of a partially transesterified poly(beta-hydroxyalkanoate), PHA, polymer produced by the bacterial strain Alcaligenes eutrophus using saponified vegetable oils as the sole carbon sources. The transesterification was carried out separately under acidic and basic conditions to obtain PHA oligomers weighing less than 10 kDa. The intact oligomers were detected in their cationized [M + Na](+) and [M + K](+) forms by MALDI-TOFMS. A composition analysis, using the MALDI-TOF spectra, indicate that the oligomers obtained via acid catalysis were terminated with a methyl 3-hydroxybutyrate end group, and those obtained by base catalysis had a methyl crotonate (olefinic) termination. In addition to HB (hydroxy butyrate), the oligomers were found to contain a small percentage of HV (hydroxy valerate). This was independently confirmed using gas chromatography/mass spectrometry (GC/MS). In comparison, the analysis of a commercial PHA polymer, transesterified under identical conditions, only showed the presence of HB, i.e. a pure PHB homopolymer. Copyright 1999 John Wiley & Sons, Ltd.

Start a Research on Biopolymer Polyhydroxyalkanoate (PHA): A Review

“…Besides, it is notable that MS techniques, such as fast-atom bombardment (FAB)-MS [176], pyrolysis/MS [177] and matrix assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) [162,178,179] have been applied for the characterization of PHA composition. Among them, MALDI-TOF-MS offers a cost-effective, straightforward and high-throughput alternative to the well-established GC-MS methods [162,179].…”

“…Among them, MALDI-TOF-MS offers a cost-effective, straightforward and high-throughput alternative to the well-established GC-MS methods [162,179]. Compared with GC-MS, MALDI-TOF-MS is a more straightforward method, and no chemical derivatization is required during sample preparation.…”

“…It could potentially be used for evaluating the M w and M n of PHAs and their oligomers [162,178,179]. Unlike GPC that can only be used in determining apparent M n values, MALDI-TOF-MS can offer accurate mass measurement of PHA [182].…”

Synthesis and structural characterization of block and random low molecular weight copolymers composed of L-lactic acid and isosorbide succinate moieties

“…8,26 Kricheldorf has obtained copolymers possessing almost block structures from transesterification reactions between two homopolymers. 26 Although Hiki et al 27 have synthesized copolymers from ring-opening copolymerization of hydroxylterminated atactic PHB with L-lactide, the block nature of those products was stated based on the absence of signals due to the alternating HB-LA sequences in the C=O regions of 13 C NMR spectra. They also claimed that the detrimental transesterification reactions have not happen during the block copolymerrizations.…”

“…From this technique, one can obtain information not only on average molar mass, molar mass distribution and end groups analysis, but also on polymerization mechanisms by analyzing the formation and the reactivity of functional groups as well as determining anomalous structures eventually formed as consequence of side reactions. [11][12][13][14][15][16][17] In this work we investigated four different approaches for the synthesis of biodegradable aliphatic polyesters composed of L-lactic acid (LLA), isosorbide (I), and succinate (S) moieties using copolymerization techniques. SEC, MALDI-TOFMS, 13 C NMR spectrometry and WAXD were used to access their structural characterization.…”