Characterization of poly(ethylene oxide)- b -poly( L -lactide) block copolymer by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (original) (raw)
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Rapid Communications in Mass Spectrometry, 2007
The results of copolymer characterization by coupling of chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) techniques and subsequent calculation of copolymer composition using a novel software tool 'MassChrom2D' are presented. For high-resolution mass analysis copolymer samples were fractionated by means of liquid adsorption chromatography (LAC). These fractions were investigated off-line by MALDI-TOF MS. Various mono-n-butyl ethers of polyethylene oxide-polypropylene oxide copolymers (PEOco-PPO) were investigated. As well as the copolymer composition presented in two-dimensional plots, the applied approach can give additional hints on specific structure-dependent separation conditions in chromatography. S. M. Weidner et al. Figure 11. MALDI-TOF MS/MS spectrum recorded for a precursor ion at m/z 2216.4 of a PEO-co-PPO polymer after chromatographic separation (top) and sections showing EO (middle) and PO distributions (bottom).
International Journal of Chemistry, 2012
The composition of narrow distribution poly ethylene oxide-propylene oxide copolymer (Mw ~ 8700 Da) was studied using matrix assisted laser desorption ionization (MALDI) mass spectrometry. The ethylene oxide-propylene oxide copolymer produced oligomers separated by 14 Da. The average resolving power over the entire spectrum was 28,000. Approximately 448 isotopically resolved peaks representing about 56 oligomers are identified. Although agreement between experimental and calculated isotopic distributions was strong, the compositional assignment was difficult. This is due to the large number of possible isobaric components. The purpose of this research is to resolve and study the composition of high mass copolymer such as ethylene oxide-propylene oxide.
The composition of narrow distribution poly ethylene oxide-propylene oxide copolymer (Mw ~ 8700 Da) was studied using matrix assisted laser desorption ionization (MALDI) mass spectrometry. The ethylene oxide-propylene oxide copolymer produced oligomers separated by 14 Da. The average resolving power over the entire spectrum was 28,000. Approximately 448 isotopically resolved peaks representing about 56 oligomers are identified. Although agreement between experimental and calculated isotopic distributions was strong, the compositional assignment was difficult. This is due to the large number of possible isobaric components. The purpose of this research is to resolve and study the composition of high mass copolymer such as ethylene oxide-propylene oxide.
Rapid Communications in Mass Spectrometry, 2009
Different cationic adducts of poly(ethylene oxide)/polystyrene block co-oligomers could be produced by adjusting the salt concentration in the mobile phase using a coupling between liquid chromatography at critical conditions and electrospray ionization mass spectrometry. Formation of doubly lithiated adducts was observed at high LiCl concentration (1 mM) while lowering the salt concentration down to 0.1 mM allowed co-oligomers to be ionized with both a proton and a lithium. The fragmentation pathways observed to occur upon collision-induced dissociation of ionized copolymers were shown to be highly dependent on the nature of the cationic adducts. As a result, complementary structural information could be reached by performing MS/MS experiments on different ionic forms of the same co-oligomer molecule. On one hand, release of the nitroxide end-group as a radical from [M+2Li]2+ was followed by a complete depolymerization of the polystyrene block, allowing both this end-group and the polystyrene segment size to be determined. On the other hand, [M+H+Li]2+ precursor ions mainly dissociated via reactions involving bond cleavages within the nitroxide moiety, yielding useful structural information on this end-group. Copyright © 2009 John Wiley & Sons, Ltd.
Analysis of copolymers by laser desorption fourier transform mass spectrometry
Journal of the American Society for Mass Spectrometry, 1990
A series of methylmethacrylatelbutylacrylate, methylmethacrylatelstyrene, and poly-(ethylene glycol)lpoly(propylene glycol) copolymers were analyzed by laser desorption Fourier transform mass spectrometry. Molecular weight distributions and overall copolymer compositions were determined. Typical spectra arise from a distribution of alkali metal cationized oligomer ions reflecting copolymer composition. Number-and weight-average molecular weights were calculated for each category of copolymer series as well as for overall copolymer mixtures. In addition, mass spectra were analyzed to estimate copolymer monomer contributions; these results were compared with manufacturer feed mix ratios as a test of the relative accuracy of the analysis. Although a dual-cell Fourier transform mass spectrometer was used, all copolymer analyses reported were carried out as single (source) cell measurements to ensure that no mass discrimination would occur. A series of Fourier transform mass spectrometry dual-cell experiments also were performed to evaluate the effect of ion transfer time on molecular weight averages and compositions. As expected, mass discrimination occurred when short transfer times and analyzer cell detection were employed. Under these conditions, molecular weight averages varied by more than 50% from values obtained in the single-cell measurements. (J Am Sot Mass Spectrum 1990, I, 66-71)
Journal of Applied Polymer Science, 2018
ABSTACT: Poly(styrene-co-4-vinylpyridine) random copolymers with different molar composition were synthesized by nitroxidemediated controlled-radical polymerization using 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide (TIPNO) as a mediator. We record the matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) spectra under various conditions, and we find (at last) that they show mostly intact ions [using 2(-4-hydroxyphenylazo-)benzoic acid as MALDI matrix]. Spectra are highly resolved, and thus they allow for the determination of all end-groups, even some less-abundant ones. Spectra are dominated by intact "dormant" copolymer chains terminated with TIPNO at one end and with (4-Bromo-phenyl)ethyl group (starting fragment) at the other one. Applying the mass analysis of copolymers (MACO) statistical model to the spectra, we show that the MACO/MALDI-TOF mass spectrometry (MS) analysis can be successfully applied to copolymers having a difference between the mass of the comonomers as small as 1 g mol −1 (the styrene and 4-vinylpyridine units are 104.15 and 105.15 g/mol, respectively), which results in overlapping isotopic patterns. The results are accurate: chemical composition evaluated by means of MS agrees with that calculated by 1 H-nuclear magnetic resonance, for all copolymers investigated. This analytical method allows to extract detailed information on the composition of the copolymer samples and their structure. Glass transition temperatures of copolymers were also determined by differential scanning calorimetry.
Tandem Fourier transform mass spectrometry of block and random copolymers
International Journal of Mass Spectrometry, 2011
In recent years, many fragmentation techniques have been developed for use with Fourier transform mass spectrometry (FTMS) in sequencing polymers. Tandem mass spectrometric techniques such as collision-induced dissociation (CID) and electron capture dissociation (ECD) were used to fragment high mass polyether and polyacrylate copolymer ions produced using external electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) sources. High resolution FTMS analysis of fragments produced by collision cell CID (QCID) is available in a new generation hybrid FTMS instrument. Although tandem QCID-TOF techniques have been used heavily to explore copolymer fragmentation, we report the first QCID-FTMS analysis of such systems. The high fragmentation efficiency of QCID combined with the high mass resolution and mass accuracy of FTMS reveals a novel fragmentation pattern of selected oligomers. This method provided evidence of re-combination of fragments in the gas phase, in that some fragments have higher mass and charges than the isolated precursor ions. QCID fragmentation of oligomers of varying size was studied in the presence of Li, Na, or Cs salts. The ECD-FTMS spectra of polyacrylates showed only side group losses. Accordingly, this technique can be used for an unknown polyacrylate sample analysis and has the potential for side group determination.
Journal of Visualized Experiments, 2018
There are many techniques that can be employed in the characterization of synthetic homopolymers, but few provide as useful of information for end group analysis as matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). This tutorial demonstrates methods for optimization of the sample preparation, spectral acquisition, and data analysis of synthetic polymers using MALDI-TOF MS. Critical parameters during sample preparation include the selection of the matrix, identification of an appropriate cationization salt, and tuning the relative proportions of the matrix, cation, and analyte. The acquisition parameters, such as mode (linear or reflector), polarization (positive or negative), acceleration voltage, and delay time, are also important. Given some knowledge of the chemistry involved to synthesize the polymer and optimizing both the data acquisition parameters and the sample preparation conditions, spectra should be obtained with sufficient resolution and mass accuracy to enable the unambiguous determination of the end groups of most homopolymers (masses below 10,000) in addition to the repeat unit mass and the overall molecular weight distribution. Though demonstrated on a limited set of polymers, these general techniques are applicable to a much wider range of synthetic polymers for determining mass distributions, though end group determination is only possible for homopolymers with narrow dispersity.