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van de Steeg AW, Vialetto L, Silva AFSD, Viegas P, Diomede P, van de Sanden MCM, van Rooij GJ. The Chemical Origins of Plasma Contraction and Thermalization in CO 2 Microwave Discharges. J Phys Chem Lett 2022; 13:1203-1208. [PMID: 35089038 DOI: 10.1021/acs.jpclett.1c03731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Thermalization of electron and gas temperature in CO2 microwave plasma is unveiled with the first Thomson scattering measurements. The results contradict the prevalent picture of an increasing electron temperature that causes discharge contraction. It is known that as pressure increases, the radial extension of the plasma reduces from ∼7 mm diameter at 100 mbar to ∼2 mm at 400 mbar. We find that, simultaneously, the initial nonequilibrium between ∼2 eV electron and ∼0.5 eV gas temperature reduces until thermalization occurs at 0.6 eV. 1D fluid modeling, with excellent agreement with measurements, demonstrates that associative ionization of radicals, a mechanism previously proposed for air plasma, causes the thermalization. In effect, heavy particle and heat transport and thermal chemistry govern electron dynamics, a conclusion that provides a basis for ab initio prediction of power concentration in plasma reactors.
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Affiliation(s)
| | - L Vialetto
- DIFFER, De Zaale 20, 5612AJ Eindhoven, The Netherlands
| | | | - P Viegas
- DIFFER, De Zaale 20, 5612AJ Eindhoven, The Netherlands
- Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářská 267/2, 611 37 Brno, Czech Republic
| | - P Diomede
- Faculty of Science and Engineering, Maastricht University, Paul Henri Spaaklaan 1, 6229 GS Maastricht, The Netherlands
| | | | - G J van Rooij
- DIFFER, De Zaale 20, 5612AJ Eindhoven, The Netherlands
- Faculty of Science and Engineering, Maastricht University, Paul Henri Spaaklaan 1, 6229 GS Maastricht, The Netherlands
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van de Steeg AW, Vialetto L, Silva AF, Peeters FJJ, van den Bekerom DCM, Gatti N, Diomede P, van de Sanden MCM, van Rooij GJ. Revisiting spontaneous Raman scattering for direct oxygen atom quantification. Opt Lett 2021; 46:2172-2175. [PMID: 33929446 DOI: 10.1364/ol.424102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 03/30/2021] [Indexed: 06/12/2023]
Abstract
In this Letter, the counterintuitive and largely unknown Raman activity of oxygen atoms is evaluated for its capacity to determine absolute densities in gases with significant O-density. The study involves ${\rm CO}_2$ microwave plasma to generate a self-calibrating mixture and establish accurate cross sections for the $^3{\!P_2}{\leftrightarrow ^3}{\!P_1}$ and $^3{\!P_2}{\leftrightarrow ^3}{\!P_0}$ transitions. The approach requires conservation of stoichiometry, confirmed within experimental uncertainty by a 1D fluid model. The measurements yield ${\sigma _{J = 2 \to 1}} = 5.27 \pm _{{\rm sys}:0.53}^{{\rm rand}:0.17} \times {10^{- 31}}\;{{\rm cm}^2}/{\rm sr}$ and ${\sigma _{J = 2 \to 0}} = 2.11 \pm _{{\rm sys}:0.21}^{{\rm rand}:0.06} \times {10^{- 31}}\;{{\rm cm}^2}/{\rm sr}$, and the detection limit is estimated to be $1 \times {10^{15}}\;{{\rm cm}^{- 3}}$ for systems without other scattering species.
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van den Bekerom DCM, Palomares Linares JM, van Veldhuizen EM, Nijdam S, van de Sanden MCM, van Rooij GJ. How the alternating degeneracy in rotational Raman spectra of CO 2 and C 2H 2 reveals the vibrational temperature. Appl Opt 2018; 57:5694-5702. [PMID: 30118084 DOI: 10.1364/ao.57.005694] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 06/01/2018] [Indexed: 06/08/2023]
Abstract
The contribution of higher vibrational levels to the rotational spectrum of linear polyatomic molecules with a center of symmetry (CO2 and C2H2) is assessed. An apparent nuclear degeneracy is analytically formulated by vibrational averaging and compared to numerical averaging over vibrational levels. It enables inferring the vibrational temperature of the bending and asymmetric stretching modes from the ratio of even to odd peaks in the rotational Raman spectrum. The contribution from higher vibrational levels is already observable at room temperature as g˜e/o=0.96/0.04 for CO2 and g˜e/o=1.16/2.84 for C2H2. The use of the apparent degeneracy to account for higher vibrational levels is demonstrated on spectra measured for a CO2 microwave plasma in the temperature range of 300-3500 K, and shown to be valid up to 1500 K.
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Gatti N, Ponduri S, Peeters FJJ, van den Bekerom DCM, Minea T, Tosi P, van de Sanden MCM, van Rooij GJ. Preferential vibrational excitation in microwave nitrogen plasma assessed by Raman scattering. ACTA ACUST UNITED AC 2018. [DOI: 10.1088/1361-6595/aabd60] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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van Rooij GJ, van den Bekerom DCM, den Harder N, Minea T, Berden G, Bongers WA, Engeln R, Graswinckel MF, Zoethout E, van de Sanden MCM. Taming microwave plasma to beat thermodynamics in CO2 dissociation. Faraday Discuss 2015; 183:233-48. [DOI: 10.1039/c5fd00045a] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The strong non-equilibrium conditions provided by the plasma phase offer the opportunity to beat traditional thermal process energy efficiencies via preferential excitation of molecular vibrations. Simple molecular physics considerations are presented to explain potential dissociation pathways in plasma and their effect on energy efficiency. A common microwave reactor approach is evaluated experimentally with Rayleigh scattering and Fourier transform infrared spectroscopy to assess gas temperatures (exceeding 104 K) and conversion degrees (up to 30%), respectively. The results are interpreted on a basis of estimates of the plasma dynamics obtained with electron energy distribution functions calculated with a Boltzmann solver. It indicates that the intrinsic electron energies are higher than is favorable for preferential vibrational excitation due to dissociative excitation, which causes thermodynamic equilibrium chemistry to dominate. The highest observed energy efficiencies of 45% indicate that non-equilibrium dynamics had been at play. A novel approach involving additives of low ionization potential to tailor the electron energies to the vibrational excitation regime is proposed.
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Affiliation(s)
- G. J. van Rooij
- Dutch Institute for Fundamental Energy Research
- 5600 HH Eindhoven
- The Netherlands
| | | | - N. den Harder
- Dutch Institute for Fundamental Energy Research
- 5600 HH Eindhoven
- The Netherlands
| | - T. Minea
- Dutch Institute for Fundamental Energy Research
- 5600 HH Eindhoven
- The Netherlands
| | - G. Berden
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
| | - W. A. Bongers
- Dutch Institute for Fundamental Energy Research
- 5600 HH Eindhoven
- The Netherlands
| | - R. Engeln
- Department of Applied Physics
- Plasma and Materials Processing Group
- Eindhoven University of Technology
- 5600 MB Eindhoven
- The Netherlands
| | - M. F. Graswinckel
- Dutch Institute for Fundamental Energy Research
- 5600 HH Eindhoven
- The Netherlands
| | - E. Zoethout
- Dutch Institute for Fundamental Energy Research
- 5600 HH Eindhoven
- The Netherlands
| | - M. C. M. van de Sanden
- Dutch Institute for Fundamental Energy Research
- 5600 HH Eindhoven
- The Netherlands
- Department of Applied Physics
- Plasma and Materials Processing Group
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van Rooij GJ, Duursma MC, de Koster CG, Heeren RM, Boon JJ, Schuyl PJ, van der Hage ER. Determination of Block Length Distributions of Poly(oxypropylene) and Poly(oxyethylene) Block Copolymers by MALDI-FTICR Mass Spectrometry. Anal Chem 2012; 70:843-50. [PMID: 21644616 DOI: 10.1021/ac970609r] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Matrix-assisted laser desorption/ionization (MALDI) was performed on an external ion source Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) to analyze the block length distributions of triblock polymers of poly(oxypropylene) and poly(oxyethylene). The first series of results presented demonstrate that the apparent molecular weight distributions are distorted. This distortion is induced by the flight-time-induced mass discrimination inherent in the experimental technique, the variation of isotopic patterns over the measured mass range, and the overlap of peaks in the spectrum. Subsequently, a method for the treatment of molecular weight distributions measured by MALDI on an external ion source FTICR-MS is developed to yield the actual molecular weight distribution and, from that, the individual block length distributions. For the first time, detailed and accurate molecular weight data were obtained on a complex sample using this methodology, which independently validates the data provided by the manufacturer. The experimentally verified random coupling hypothesis proves the validity of the methodology.
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Affiliation(s)
- G J van Rooij
- FOM Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, The Netherlands
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Rooij GJV, Wright GM. Diagnostics for Erosion and Deposition Processes in Fusion Plasmas. Fusion Science and Technology 2012. [DOI: 10.13182/fst12-a13526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- G. J. van Rooij
- FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM Edisonbaan 14, 3439 MN Nieuwegein, The Netherlands
| | - G M. Wright
- FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM Edisonbaan 14, 3439 MN Nieuwegein, The Netherlands
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Shumack AE, Schram DC, Biesheuvel J, Goedheer WJ, van Rooij GJ. Diagnosing ions and neutrals via n=2 excited hydrogen atoms in plasmas with high electron density and low electron temperature. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 83:036402. [PMID: 21517599 DOI: 10.1103/physreve.83.036402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2010] [Revised: 12/08/2010] [Indexed: 05/30/2023]
Abstract
Ion and neutral parameters are determined in the high electron density, magnetized, hydrogen plasma beam of an ITER divertor relevant plasma via measurements of the n=2 excited neutrals. Ion rotation velocity (up to 7 km/s) and temperature (2-3 eV~T_{e}) are obtained from analysis of Hα spectra measured close to the plasma source. The methodology for neutral density determination is explained whereby measurements in the linear plasma beam of Pilot-PSI are compared to modeling. Ground-state atomic densities are obtained via the production rate of n=2 and the optical thickness of the Lyman-α transition (escape factor ~0.6) and yield an ionization degree >85% and dissociation degree in the residual gas of ~4%. A 30% proportion of molecules with a rovibrational excitation of more than 2 eV is deduced from the production rate of n=2 atoms. This proportion increases by more than a factor of 4 for a doubling of the electron density in the transition to ITER divertor relevant electron densities, probably because of a large increase in the production and confinement of ground-state neutrals. Measurements are made using laser-induced fluorescence (LIF) and absorption, the suitability of which are evaluated as diagnostics for this plasma regime. Absorption is found to have a much better sensitivity than LIF, mainly owing to competition with background emission.
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Affiliation(s)
- A E Shumack
- FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, Trilateral Euregio Cluster, Nieuwegein, The Netherlands
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van Rooij GJ, Wright GM. Diagnostics for Erosion and Deposition Processes in Fusion Plasmas. Fusion Science and Technology 2010. [DOI: 10.13182/fst10-a9435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- G. J. van Rooij
- FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM Edisonbaan 14, 3439 MN Nieuwegein, The Netherlands
| | - G. M. Wright
- FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM Edisonbaan 14, 3439 MN Nieuwegein, The Netherlands
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Shumack AE, Veremiyenko VP, Schram DC, de Blank HJ, Goedheer WJ, van der Meiden HJ, Vijvers WAJ, Westerhout J, Lopes Cardozo NJ, van Rooij GJ. Rotation of a strongly magnetized hydrogen plasma column determined from an asymmetric Balmer-beta spectral line with two radiating distributions. Phys Rev E Stat Nonlin Soft Matter Phys 2008; 78:046405. [PMID: 18999541 DOI: 10.1103/physreve.78.046405] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2008] [Indexed: 05/27/2023]
Abstract
A potential buildup in front of a magnetized cascaded arc hydrogen plasma source is explored via E x B rotation and plate potential measurements. Plasma rotation approaches thermal speeds with maximum velocities of 10 km/s. The diagnostic for plasma rotation is optical emission spectroscopy on the Balmer-beta line. Asymmetric spectra are observed. A detailed consideration is given on the interpretation of such spectra with a two distribution model. This consideration includes radial dependence of emission determined by Abel inversion of the lateral intensity profile. Spectrum analysis is performed considering Doppler shift, Doppler broadening, Stark broadening, and Stark splitting.
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Affiliation(s)
- A E Shumack
- FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, Trilateral Euregio Cluster, Nieuwegein, The Netherlands
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van Rooij GJ, Wright GM. Diagnostics for Erosion and Deposition Processes in Fusion Plasmas. Fusion Science and Technology 2008. [DOI: 10.13182/fst08-a1729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- G. J. van Rooij
- FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM Edisonbaan 14, 3439 MN Nieuwegein, The Netherlands
| | - G. M. Wright
- FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM Edisonbaan 14, 3439 MN Nieuwegein, The Netherlands
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van der Meiden HJ, Al RS, Barth CJ, Donné AJH, Engeln R, Goedheer WJ, de Groot B, Kleyn AW, Koppers WR, Lopes Cardozo NJ, van de Pol MJ, Prins PR, Schram DC, Shumack AE, Smeets PHM, Vijvers WAJ, Westerhout J, Wright GM, van Rooij GJ. High sensitivity imaging Thomson scattering for low temperature plasma. Rev Sci Instrum 2008; 79:013505. [PMID: 18248032 DOI: 10.1063/1.2832333] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
A highly sensitive imaging Thomson scattering system was developed for low temperature (0.1-10 eV) plasma applications at the Pilot-PSI linear plasma generator. The essential parts of the diagnostic are a neodymium doped yttrium aluminum garnet laser operating at the second harmonic (532 nm), a laser beam line with a unique stray light suppression system and a detection branch consisting of a Littrow spectrometer equipped with an efficient detector based on a "Generation III" image intensifier combined with an intensified charged coupled device camera. The system is capable of measuring electron density and temperature profiles of a plasma column of 30 mm in diameter with a spatial resolution of 0.6 mm and an observational error of 3% in the electron density (n(e)) and 6% in the electron temperature (T(e)) at n(e) = 4 x 10(19) m(-3). This is achievable at an accumulated laser input energy of 11 J (from 30 laser pulses at 10 Hz repetition frequency). The stray light contribution is below 9 x 10(17) m(-3) in electron density equivalents by the application of a unique stray light suppression system. The amount of laser energy that is required for a n(e) and T(e) measurement is 7 x 10(20)n(e) J, which means that single shot measurements are possible for n(e)>2 x 10(21) m(-3).
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Affiliation(s)
- H J van der Meiden
- FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, partner in the Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein, The Netherlands
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Scheffer PG, Henry RMA, Wever EJM, van Rooij GJ, Bos G, Heine RJ, Dekker JM, Diamant M, Stehouwer CDA, Nijpels G, Blankenstein MA, Teerlink T. LDL oxidative modifications in well- or moderately controlled type 2 diabetes. Diabetes Metab Res Rev 2004; 20:298-304. [PMID: 15250032 DOI: 10.1002/dmrr.461] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND The aim of the study was to examine, by measurement of specific indicators of free radical-mediated oxidation of LDL, whether there is evidence of increased in vivo oxidation of LDL in type 2 diabetic patients, and to investigate their associations with carotid intima media thickness (IMT). METHODS In native LDL, we quantified five different products of LDL oxidation reflecting various stages of LDL oxidative modification in 38 individuals with well- or moderately controlled type 2 diabetes (HbA(1c) </= 8.5%) and 38 gender-matched subjects with normal glucose metabolism. Baseline conjugated dienes (BCD), 7-OH-glycero-phosphocholine (7-OH-GPC), lyso-phosphatidylcholine (lyso-PC), and ketocholesterol were determined in LDL, and circulating in vivo oxidized apolipoprotein B100 (Ox-apoB) was measured in plasma. The IMT of the carotid artery was measured by ultrasound. RESULTS Borderline higher carotid IMT values were observed in individuals with diabetes (0.88 +/- 0.14 vs 0.83 +/- 0.11 mm, p = 0.06). LDL-ketocholesterol (45.5 +/- 19.4 vs 37.1 +/- 13.8 nmol/mmol LDL-cholesterol, p < 0.05) and Ox-apoB (25.3 +/- 5.5 vs 22.2 +/- 5.8 U/mmol LDL-cholesterol, p < 0.05) were significantly increased in diabetic patients. The concentration of BCD, 7-OH-GPC and lyso-PC in LDL did not differ between diabetic patients and control subjects. No significant correlations were demonstrated between the measured indicators of LDL oxidation and carotid IMT. CONCLUSION Levels of BCD, 7-OH-GPC and lyso-PC, that is, intermediary products of LDL oxidation, were not significantly elevated, but ketocholesterol and Ox-apoB, that is, stable end products of the oxidation process, were increased in diabetic patients. We conclude that in vivo oxidation of LDL is increased, even in subjects with well- or moderately controlled type 2 diabetes.
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Affiliation(s)
- P G Scheffer
- Metabolic Laboratory, Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands.
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van Rooij GJ, Duursma MC, Heeren RMA, Boon JJ, de Koster CG. High resolution end group determination of low molecular weight polymers by matrix-assisted laser desorption ionization on an external ion source fourier transform ion cyclotron resonance mass spectrometer. J Am Soc Mass Spectrom 1996; 7:449-57. [PMID: 24203399 DOI: 10.1016/1044-0305(96)00003-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/1995] [Revised: 12/19/1995] [Accepted: 12/19/1995] [Indexed: 05/14/2023]
Affiliation(s)
- G. J. van Rooij
- Unit for Macromolecular Mass Spectrometry, FOM-Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ, Amsterdam, The Netherlands
| | - M. C. Duursma
- Unit for Macromolecular Mass Spectrometry, FOM-Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ, Amsterdam, The Netherlands
| | - R. M. A. Heeren
- Unit for Macromolecular Mass Spectrometry, FOM-Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ, Amsterdam, The Netherlands
| | - J. J. Boon
- Unit for Macromolecular Mass Spectrometry, FOM-Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ, Amsterdam, The Netherlands
| | - C. G. de Koster
- Unit for Macromolecular Mass Spectrometry, FOM-Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ, Amsterdam, The Netherlands
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de Koster CG, Duursma MC, van Rooij GJ, Heeren RM, Boon JJ. Endgroup analysis of polyethylene glycol polymers by matrix-assisted laser desorption/ionization Fourier-transform ion cyclotron resonance mass spectrometry. Rapid Commun Mass Spectrom 1995; 9:957-62. [PMID: 7670157 DOI: 10.1002/rcm.1290091018] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) by external injection of matrix-assisted laser desorbed and ionized (MALDI) polymers offers good possibilities for characterization of low molecular weight homopolymers (MW range up to 10 kDa). The molecular masses of the molecular weight distribution (MWD) components of underivatized and derivatized (dimethyl, dipropyl, dibutyl and diacetyl) polyethylene glycol (PEG) 1000 and 4000 were measured by MALDI-FTICR-MS. These measurements have been performed using a commercial FTICR spectrometer with a home-built external ion source. MALDI of the samples with a 2,5-dihydroxybenzoic acid matrix in a 1000:1 matrix-to-analyte molar ratio produces sodiated molecules in a sufficient yield to trap the ions in the ICR cell. The masses of the molecular weight distribution of PEG components were measured in broad-band mode with a mass accuracy of < 5 ppm in the mass range around 1000 u and within 40 ppm accuracy around 4000 u. From these measurements, the endgroup mass of the polymer was determined by correlation of the measured component mass with the degree of polymerization. The masses of the PEG endgroups have been determined within a deviation of 3-10 millimass units for the PEG1000 derivatives and 10-100 millimass units for the PEG4000 derivatives, thus confirming the identity of the distal parts of the model compounds.
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Affiliation(s)
- C G de Koster
- Unit for Macromolecular Mass Spectrometry, FOM Institute for Atomic and Molecular Physics, Amsterdam, The Netherlands
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