Comparison of mass spectrometric techniques for generating molecular weight information on a class of ethoxylated oligomers

Parees, David M.; Hanton, Scott D.; Clark, Paula A. Cornelio; Willcox, Dale A.

doi:10.1016/s1044-0305(97)00291-2

Cited by 63 publications

(59 citation statements)

References 51 publications

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“…[10][11][12][13][14] Recently, Parees et al surveyed MALDI, SIMS and ESI, as well as field desorption (FD) and fastatom bombardment (FAB) for generating molecular weight information from ethoxylated oligomers and compared the relative merits of each ionization technique for this type of analysis. 15 In the present survey, we examine the utility of MALDI, SIMS and ESI in measuring the M n , M w and polydispersity values of two model polymers: poly(dimethylsiloxane) (PDMS) and poly(ethylene glycol) (PEG). PDMS and PEG were chosen as model systems chiefly because of their welldefined molecular weights, their importance as surfactants in biomaterials (for example, contact lenses) and because many of their surface and solution-phase properties are wellunderstood.…”

Section: Introductionmentioning

confidence: 99%

Quantitative mass spectrometry of technical polymers: a comparison of several ionization methods

Yan¹,

Ammon²,

Gardella³

et al. 1998

Eur. J. Mass Spectrom.

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The development of soft ionization methods such as matrix-assisted laser desorption/ionization (MALDI), electrospray ionization (ESI) and secondary ion mass spectrometry (SIMS) has led to an increased use of mass spectrometry in characterizing technical (synthetic) polymers. In this paper, we compare the relative performance of these three ionization methods for characterizing the molecular weights, polydispersities and quantification of relative amounts of polymer components in mixtures. Two polymers used in biomaterials, poly(dimethylsiloxane) and poly(ethylene glycol), are employed as the model polymer systems for our survey because of their well-defined molecular weights and importance as surfactants in biomaterials and because many of their surface and solutionphase properties are well understood. Matrix-assisted laser desorption/ionization can be used to examine the surface and bulk composition of biomaterials, whereas secondary ion mass spectrometry is used for examining monolayer and submonolayer coverage of polymers on surfaces and electrospray ionization is suited for examination of extractables from biomaterials. Secondary ion mass spectrometry and electrospray show discriminate behavior against ionization of higher molecular weight oligomers, especially of poly(dimethylsiloxane). Matrix-assisted laser desorption/ionization appears to exhibit the best performance for reliable molecular weight determination at higher masses and polydispersity characterization as well as for quantification of components in polymer mixtures. The results are discussed within the context of the ionization mechanisms by which each soft ionization technique operates and by the attributes of the mass analyzers (time-of-flight and Fourier transform mass spectrometers) employed.

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Section: Introductionmentioning

confidence: 99%

Quantitative mass spectrometry of technical polymers: a comparison of several ionization methods

Yan¹,

Ammon²,

Gardella³

et al. 1998

Eur. J. Mass Spectrom.

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“…Vacuum MALDI TOFMS experiments have already characterized the molecular weight distributions, chemical composition, and PSD of S4XX surfactants [10,18]. AP MALDI can also generate meaningful mass spectra for these materials.…”

Section: Resultsmentioning

confidence: 99%

“…Previous gas chromatography (GC) work on S4XX materials shows that for low degree of ethoxylation telomers, the two alcohol sites do not tend to ethoxylate symmetrically [18]. Due to the limitations of volatility, only the low degree of ethoxylation telomers can be studied by GC.…”

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confidence: 99%

The fragmentation of ethoxylated surfactants by AP-MALDI-QIT

Hanton

Parees

Zweigenbaum

2006

J. Am. Soc. Mass Spectrom.

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Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry has become an important technique to characterize the chemical structure of industrial polymer materials. MALDI methods have been developed to address a broad variety of different polymer materials containing different chemistries. One of the key aspects of the typical MALDI experiment is the generation of intact ions. The development of Atmospheric Pressure (AP) MALDI quadrupole ion trap (QIT) instruments has opened another channel to obtaining MS/MS experiments for polymer samples. These experiments provide a new method to obtain chemical structure information from MALDI experiments. Collision-Induced Dissociation (CID) provides an improved MALDI MS/MS experiment that can be done on readily available mass spectrometers. AP MALDI QIT techniques have been successfully applied to a variety of synthetic polymers. This work explores the applicability of AP MALDI QIT methods to relatively low molecular weight ethoxylated surfactants. In these experiments we show the CID fragmentation mass spectra on some ethoxylated surfactants, and demonstrate the existence of analyte matrix clusters. [5][6][7]. MALDI can generate important data on the telomer repeat units, end groups, and average molecular weights of these materials. MALDI methods have been developed to address a broad variety of different polymer materials containing different chemistries. One of the key aspects of the typical MALDI experiment is the generation of intact ions. MALDI mass spectra generally show little fragmentation. The production of intact ions is vital for the quantitation of average molecular weights, but limits the amount of chemical structural information that can be obtained from the data.The development of MALDI post-source decay (PSD) techniques has opened a new method to obtain chemical structure information from MALDI experiments [8 -10]. Unfortunately, PSD experiments are relatively crude MS/MS experiments. The range of masses submitted for the fragmentation is broad, the mass resolution and mass accuracy of the fragment spectra is not as good as the MALDI data, and there is very limited control of the energy deposition into the fragmentation process.The development of atmospheric pressure (AP) MALDI instruments has enabled the utilization of different mass analyzers for MALDI [11,12]., One of the key benefits to changing the mass analyzer in a MALDI experiment is to significantly improve the MS/MS capability. A quadrupole ion trap (QIT) mass spectrometer is an excellent choice in this regard. Some early work showed examples of high quality MS/MS experiments on MALDI generated peptides [13][14][15][16]. The ability to analyze synthetic polymers using AP MALDI methods on a QIT have also been demonstrated [17].With a QIT mass spectrometer we can accomplish high quality collision-induced dissociation (CID) MS/ MS. The instrument is capable of selecting an individual ion from the mass spectrum for fragmentation. The fragmentation gas and relative energy can be controlled...

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“…Desorption of intact oligomers provides a direct measure of molecular weight distribution (MWD) from which a molecular weight average can be evaluated. According to the recent reports [21,22] on the comparison of mass spectrometric techniques, TOF-SIMS produced a result similar to electrospray ionization (ESI) and fast atom bombardment (FAB). They consistently showed lower MW averages compared with gel permeation chromatography (GPC)-deduced results, whereas matrix-assisted laser desorption/ionization (MALDI) and field desorption (FD) results are higher.…”

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confidence: 99%

Quantitative TOF-SIMS analysis of oligomeric degradation products at the surface of biodegradable poly(α-hydroxy acid)s

Lee

Gardella

2002

J. Am. Soc. Mass Spectrom.

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This paper reports the development of a new method for quantification of the hydrolytic surface degradation kinetics of biodegradable poly(␣-hydroxy acid)s using time-of-flight secondary ion mass spectrometry (TOF-SIMS). We report results from static SIMS spectra of a series of poly(␣-hydroxy acid)s including poly(glycolic acid), poly( L -lactic acid), and random poly( D,L -lactic acid-co-glycolic acid) hydrolyzed in various buffer systems. The distribution of the most intense peak intensities of ions generated in high mass range of the spectrum reflects the intact degradation products (oligomeric hydrolysis products) of each biodegradable polymer. First, a detailed analysis of the oligomeric ions is given based on rearrangement of the intact hydrolysis products. The pattern of ions can distinguish both degradation-generated intact oligomers and their fragment ion peaks with a variety of combinations of each repeat unit. Then, the integration and summation of the area of all ion peaks with the same number of repeat units is proposed as a measurement that provides a more accurate MW average than the typically used method which counts only the most intense peak. The multiple ion summation method described in this paper would be practical in the improvement of quantitative TOF-SIMS studies as a better data reduction method, especially in the surface degradation kinetics of biodegradable polymers. , additives in a polymer [13], and detailed structural characterization [14,15] and quantitative analysis [16 -20] of polymers. Most TOF-SIMS spectra of polymers have been obtained in the mass range m/z Ͻ10,000 [5, 18 -20].Two main processes are observed in the TOF-SIMS spectra of polymers; these are the fragmentation of polymer chains and the desorption of intact oligomers. Fragmentation under ion bombardment in ultra-high vacuum (UHV) environment generates distinct fragmentation patterns that are unique to a given polymer. From the fragmentation patterns the mass of the repeat unit, terminal groups, side groups, and functional groups in a repeat unit can be determined [14,15]. Desorption of intact oligomers provides a direct measure of molecular weight distribution (MWD) from which a molecular weight average can be evaluated. According to the recent reports [21,22] on the comparison of mass spectrometric techniques, TOF-SIMS produced a result similar to electrospray ionization (ESI) and fast atom bombardment (FAB). They consistently showed lower MW averages compared with gel permeation chromatography (GPC)-deduced results, whereas

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Comparison of mass spectrometric techniques for generating molecular weight information on a class of ethoxylated oligomers

Cited by 63 publications

References 51 publications

Quantitative mass spectrometry of technical polymers: a comparison of several ionization methods

Quantitative mass spectrometry of technical polymers: a comparison of several ionization methods

The fragmentation of ethoxylated surfactants by AP-MALDI-QIT

Quantitative TOF-SIMS analysis of oligomeric degradation products at the surface of biodegradable poly(α-hydroxy acid)s

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