Laser desorption ionization mass molecular weight distribution

Cryoscopy and ebulioscopy can be used for the measurement of Mn for polymers in a similar way to the application on smaller molecules, and the procedure is used mainly when Mn < 2 10. I LDI-MS (matrix-assisted laser desorption ionization-mass spectroscopy) allows the measurement of both Mn and M , as well as the molecular weight distribution, which indicates the variation of w, (weight fraction of the component i ), as a function of M,. 

The molecular weights and molecular weight distributions (MWD) of phenolic oligomers have been evaluated using gel permeation chromatography (GPC),23,24 NMR spectroscopy,25 vapor pressure osmometry (VPO),26 intrinsic viscosity,27 and more recently matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).28... 

Finally, another method commonly used to characterize these copolymeric materials is that of matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. When using this technique, it is possible to investigate the molecular weight distributions, end groups, and polymer constitution of low-molecular-weight samples [63], MALDI-TOF may also provide vital... 

O Conner, P. B., Duursma, M. C., van Rooij, G. J., Heeren, R. M. A., and Boon, J. J., "Correction of Time-of-Flight Shifted Polymeric Molecular Weight Distributions in Matrix-Assisted Laser Desorption/Ionization Fomier Transform Mass Spectrometry," Anal. Chem., 69, 2751-2755,1997. 

Spickermann, J., Martin, K., Rader, H. J., Mullen, K., Schlaad, H., Muller, A. H. E., and Kruger, R.-R, Quantitative Analysis of Broad Molecular Weight Distributions Obtained by Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry, Eur. Mass Spectrom., 2, 161, 1996. 

Guo, B., Chen, H., and Liu, R. X., Observation of Varying Molecular Weight Distributions in Matrix-assisted Laser Desorption/Ionization lime-of-Flight Analysis of Polymethyl Methacrylate, Rapid Comm. Mass. Spectrom., 11, 781,... 

Vitalini, D., Mineo, P, and Scamporrino, E., Further Application of a Procedure for Molecular Weight and Molecular Weight Distribution Measurement of Polydisperse Polymers from Their Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectra, Macromolecules, 30, 5285,1997. 

Zammit, M. D., Davis, T. R, and Haddleton, D. M., Determination of the Propagation Rate Coefficient (kp) and Termination Mode in the Free-Radical Polymerization of Methyl Methacrylate, Employing Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry for Molecular Weight Distribution Anal5 is, Macromolecules, 29, 492, 1996. 

In recent years, the technology of mass spectroscopy has been well developed. The matrix-assisted Laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) can be applied to measure the molecular weights of macromolecules (up to one million Dalton) due to its high sensitivity and its wide response range. In combinatiOTi with the distribution of fragment lengths, it can be used to characterize those bio- and synthetic macromolecules with complicated molecular architectures. 

J.J. (1997) Correction of time-of-flight shifted polymeric molecular weight distributions in matrix-assisted laser desorption/ionization Fourier transform mass spectrometry. Anal. Chem., 69,... 

Matrix assisted laser desorption ionization (MALDI) is a frequently used ionization technique, but it is rarely used as an online detector. The sample stream is appUed to a target plate, and it is allowed to cocrystallize with the matrix, which is subsequently desorbed, ionized with a lasCT, and analyzed in the MS. MALDI/TOF has been successfully used to determine molecular weight distributions of fractions collected after thermal FFF separation of polydis-pCTse polymers. MALDI is a good ion source, due to the soft ionization with high effrciency and simple mass spectra, even for heavier molecules, since the m ority carry only a single charge. 

Hortal, A.R., Martinez-Haya, B., Lobato, M.D., Pedrosa, J.M., Lago, S. (2006) On the determination of molecular weight distributions of asphaltenes and their aggregates in laser desorption ionization experiments./. Mass Spectrom., 41,960-968. 

C. Becker, K. Qian, and D. H. Russell, Molecular weight distributions of asphaltenes and deasphaltened oils studied by laser desorption ionization and ion mobility mass spectrometry. Anal. Chem. 80, 8592-8597, 2008. 

Tatro SR, Baker GR, Fleming R, Harmon JP. Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry determining Mark-Houwink-Sakurada parameters and analyzing the breadth of polymer molecular weight distributions. Polymer 2002 43 2329-2335. 

Mass Spectrometry. An alternative to using GPC with viscometry and li t scattering detection for the determination of low molecular wei t polymer distributions is mass spectrometry. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDITOFMS) can give fast, accurate information about the degree of polymerization (molecular weight stribution). 

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