Time-of-flight secondary ion mass spectrometry of polymer materials

Leyen, D. van; Hagenhoff, Birgit; Niehuis, E.; Benninghoven, A.; Bletss, I. V.; Hercules, David M.

doi:10.1116/1.576047

Cited by 80 publications

(23 citation statements)

References 1 publication

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“…In fact, in SIMS measurements on polystyrene molecular weight standards, the cationised yields of intact oligomers were found to decrease by a factor of about 20 as the oligomer mass increased from about 1000±2000 to 7000. 14 The high yield ratios observed here suggest that insulin molecules are segregating at the surface during drying of the sprayed solution. In that case the molar concentration ratio is not the relevant number but rather the (unknown) surface concentration ratio.…”

Section: Resultsmentioning

confidence: 89%

Effect of water treatment on analyte and matrix ion yields in matrix‐assisted time‐of‐flight secondary ion mass spectrometry: the case of insulin in and on hydroxycinnamic acid

Szymczak¹,

Wittmaack²

2002

Rapid Comm Mass Spectrometry

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A systematic study was performed to identify the origin of surprisingly high analyte-to-matrix yield ratios recently observed in time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis of oligo- and polypeptides mixed in matrices of alpha-cyano-4-hydroxycinnamic acid (4HCCA). Several sets of samples of porcine insulin in 4HCCA (1:3100 molar) were prepared from liquid solutions by a nebuliser technique, with more than one order of magnitude variation in sprayed material (substrate silicon). Following different periods of storage in air and/or vacuum as well as exposure to high-purity water, TOF-SIMS analysis was performed under oblique impact of 22 keV SF5+. Treatment with water involved either deposition of a droplet covering the whole sample for times between 1 and 20 min or spraying with water in droplet equivalent quantities. The analyte and matrix molecules were detected as protonated molecules (insulin also in doubly protonated form). Even the as-prepared samples usually showed insulin-to-4HCCA yield ratios exceeding the molar ratio of the mixed material. Upon ageing in vacuum the matrix ion yields remained constant but the analyte yields decreased, partly due to break-up of intrachain disulfide bonds. Water treatment resulted in a pronounced decrease in the 4HCCA yield, typically by a factor of five, in parallel with an increase of the insulin yield, by up to a factor of four. Evidence is provided that these changes occur concurrently with a partial dissolution of 4HCCA at the sample surface. The enhanced insulin yield was not correlated with the Na+ yield. The typically 20-fold increase in the insulin-to-4HCCA yield ratio, generated by water exposure of the samples, provides the explanation for the high yield ratios observed previously with water-treated samples. Spraying with water or repeated exposure to water droplets caused a pronounced degradation of the insulin parent yields in combination with an increasing appearance of signals due to the B- and A-chains of insulin. To clarify the issue of surface segregation, a few samples were prepared by spraying acetone-diluted solutions of insulin on previously deposited layers of 4HCCA. Whereas the insulin yields from as-prepared samples were rather low, the yields observed after water treatment were comparable with those observed with samples of insulin in 4HCCA. The results suggest that a large amount of insulin is present at the surface of samples prepared from liquid mixtures of insulin in 4HCCA. With both methods of sample preparation, however, high secondary ion yields of insulin were only obtained after exposure of the samples to water. The chemical changes responsible for this beneficial effect still need to be identified.

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Section: Resultsmentioning

confidence: 89%

Effect of water treatment on analyte and matrix ion yields in matrix‐assisted time‐of‐flight secondary ion mass spectrometry: the case of insulin in and on hydroxycinnamic acid

Szymczak¹,

Wittmaack²

2002

Rapid Comm Mass Spectrometry

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“…The depth profiling was performed at room temperature. [16][17][18]26,27]. The spectral data from m/z 5 to 250 shows a typical enhancement of ion intensities as a consequence of using a polyatomic source over a monoatomic source, which ranges in enhancement from 50-to 500-fold.…”

Section: Tof-simsmentioning

confidence: 98%

“…Polystyrene (PS) was chosen as the first in a series of polymers investigated both because of its commercial viability and the wide range of molecular weights that can be synthesized with low polydispersity. PS has been previously investigated to determine the effects of molecular weight on the SIMS data of polymers using monoatomic sources of Ar + and Ga + [16][17][18]. Polystyrene has also been investigated with polyatomic primary sources both experimentally [2,3,9,14,[19][20][21] and with molecular dynamic simulations [22,23], although molecular weight effects were not the primary investigation in those studies.…”

Section: Introductionmentioning

confidence: 98%

Investigation of molecular weight effects of polystyrene in ToF-SIMS using C60+ and Au+ primary ion beams

Piwowar¹,

Lockyer²,

Vickerman³

2008

Applied Surface Science

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“…The difficulty in detecting the molecular ion signals for high-molecularweight samples >2000 Da has been discussed already and exemplified in the literature. 21,23 For higher masses of the analysed molecules, the desorption and detection efficiency of molecular ions are lower.…”

Section: Detection Of Dendritic Aliphatic Polyester Adsorbates On Silmentioning

confidence: 99%

Cationization of dendritic macromolecule adsorbates on metals studied by time‐of‐flight secondary ion mass spectrometry

Coullerez¹,

Mathieu²,

Lundmark³

et al. 2003

Surface & Interface Analysis

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allowed the studied polymers to be identified. The whole molecular species were observed for Bis-MPA dendrons and dendrimers up to 3000 Da for hydroxyl or acetonide-terminated derivatives. The success of the so-called cationization experiments with metal substrates compared with analysis of molecular adsorbates on silicon is highlighted. The ToF-SIMS sensitivity appeared useful to provide information about the molecular end-groups or to highlight incomplete reaction occurring during some deprotection step of the synthesis. Only uncationized fragments of low masses were detected for the hyperbranched polyesters. This result suggested the effect of molecular asymmetry and/or flattening of the molecules on the substrates, which hampered the molecule lift-off efficiency. Nevertheless, the hyperbranched polyethers were characterized based on the peak distribution of intensities, which allowed estimation of their molecular weight average. This work was intended to illustrate the capabilities of ToF-SIMS to analyse dendritic polymers on surfaces.

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Time-of-flight secondary ion mass spectrometry of polymer materials

Cited by 80 publications

References 1 publication

Effect of water treatment on analyte and matrix ion yields in matrix‐assisted time‐of‐flight secondary ion mass spectrometry: the case of insulin in and on hydroxycinnamic acid

Effect of water treatment on analyte and matrix ion yields in matrix‐assisted time‐of‐flight secondary ion mass spectrometry: the case of insulin in and on hydroxycinnamic acid

Investigation of molecular weight effects of polystyrene in ToF-SIMS using C60+ and Au+ primary ion beams

Cationization of dendritic macromolecule adsorbates on metals studied by time‐of‐flight secondary ion mass spectrometry

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