Fourier transform mass spectrometry , polymer

Brown, C. E., Kovacic, R, Wilkie, C. A., Hein, R. E., Yaniger, S. I., and Cody, R. B. J., "Polynuclear and Halogenated Structures in Polyphenylenes Synthesized from Benzene, Biphenyl, and p-Terphenyl under Various Conditions Characterization by Laser Desorption/Fourier Transform Mass Spectrometry,". Polym. Sci. Polym. Chem, Ed, 24, 255-267,1986. 

Aaserud, D. ]., Prokai, L., and Simonsick, W.J., Jr., Gel permeation chromatography coupled to Fourier transform mass spectrometry for polymer characterization, Anal. Chem., 71, 4793, 1999. 

Laser desorption methods (such as LD-ITMS) are indicated as cost-saving real-time techniques for the near future. In a single laser shot, the LDI technique coupled with Fourier-transform mass spectrometry (FTMS) can provide detailed chemical information on the polymeric molecular structure, and is a tool for direct determination of additives and contaminants in polymers. This offers new analytical capabilities to solve problems in research, development, engineering, production, technical support, competitor product analysis, and defect analysis. Laser desorption techniques are limited to surface analysis and do not allow quantitation, but exhibit superior analyte selectivity. 

R. S. Brown, D. A. Weil, and C. L. Wilkins, "Laser Desorption-Fourier Transform Mass Spectrometry for the Characterization of Polymers," Macromolecules, 19, 1255-1260 (1986). 

Laser desorption Fourier transform mass spectrometry (LD-FTMS) results from a series of peptides and polymers are presented. Successful production of molecular ions of peptides with masses up to 2000 amu is demonstrated. The amount of structurally useful fragmentation diminishes rapidly with increasing mass. Preliminary results of laser photodissociation experiments in an attempt to increase the available structural information are also presented. The synthetic biopolymer poly(phenylalanine) is used as a model for higher molecular weight peptides and produces ions approaching m/z 4000. Current instrument resolution limits are demonstrated utilizing a polyethylene-glycol) polymer, with unit mass resolution obtainable to almost 4000 amu. 

Once the polymer molecules have been transferred to the gas phase as ions, they are separated on the basis of their mass-to-charge ratio. Mass spectrometers nsed for MALDI analysis may differ, but for those that are commercially available, separation is effected by TOE Other methods such as quadrupole filter and Fourier transform mass spectrometry (FTMS) may also be used. 

Maziarz, E.R, Baker, G.A., and Wood, T.D. Capitalizing on the high mass accuracy of electrospray ionization Fourier transform mass spectrometry for synthetic polymer characterization A detailed investigation of poly(dimethylsiloxane). Macromolecules, 32, 4411, 1999. 

It is clear that laser desorption Fourier transform mass spectrometry has significant potential as a polymer analysis tool. It works especially well for polar polymers and additives witii molecular weights lower than 10000 Da. AAftth proper attention to analytical details, it is a highly accurate and quite specific way to characterize tiiese substances and can provide unrivaled mass resolution. As is obvious from this chapter, the application of LD-FTMS to polymer analytical problems is an active area of investigation in many laboratories. AAftth the continuing proliferation of commercial FTMS instruments, LD-FTMS applications of polymer analysis should be expected to expand for the foreseeable future. There is no question tiiat tiiis method provides a versatile alternative to tire numerous less specific analytical methods employed to date. 

Kahr, M. S. and Wilkins, C. L., "Silver Nitrate Chemical Ionization for Analysis of Hydrocarbon Polymers by Laser Desorption Fourier Transform Mass Spectrometry," /. Am. Soc. Mass Spectrom., 4, 453-460,1993. 

Srzic, D., Martinovic, S., Pasa ToUc, L., Kezele, N., Kazazic, S., Senkovic, L., Shevchenko, S. M., and Klasinc, L., "Laser Desorption Fourier Transform Mass Spectrometry of Natural Polymers," Rapid Commun. Mass Spectrom., 10,580-582, 1996. 

Johlman, C. L., Wilkins, C. L., Hogan, J. D., Donovan, T. L., Laude, D. A. J., and Youssefi, M. J., "Laser Desorption/Ionization Fourier Transform Mass Spectrometry and Fast Atom Bombardment Spectra of Nonvolatile Polymer Additives," Anal. Chem., 62, 1167-1172, 1990. 

Pastor, S.J. and Wilkins, C.L. (1997) Analysis of hydrocarbon polymers by matrix-assisted laser desorption/ ionization-Fourier transform mass spectrometry. J. Am. Soc. Mass Spectrom., 8, 225-233. 

Borgmann, S. and Wilkins, C.L (2010) Polymer analysis with Fourier transform mass spectrometry, in MALDI Mass Spectrometry (ed. L. Li), Wiley, New York, pp53-85. 

Fourier transform mass spectrometry (ftms) is an ion cyclotron resonance method (3,4). This method is currently limited to masses less than 20,000. Thus, it works well for lower molecular mass polymers. Often it is used with MALDI. However, the MALDI process is so energetic that the initial velocity of the analytes can cause some intensity difficulties that make the method difficult to quantify. Because of the expense of the magnet required to obtain quahty data with this method, only a few laboratories use this method. 

Charles 1. Wilkins is currently a Distinguished Professor in the Department of Chemistry and Biochemistry at the University of Arkansas (Fayetteville). His interests inclnde mass spectrometry of polymer and copolymer materials, Fourier transform mass spectrometry, and the development of new methods to improve the utility of analytical mass spectrometry. Past research has dealt with applications of laboratory computers in chemistry, graph theoretic analysis of chemical problems, and research in chemometrics. Investigations of hyphenated analytical systems such as gas chromatography-infrared mass spectrometry and HPLC-NMR have also been of interest. He is the author of more than 235 scientific papers and 21 book chapters, in addition to editing eight books on a variety of chemistry topics. 

These relatively new techniques viz laser desorption/ionization Fourier transform mass spectrometry and fast atom bombardment and laser desorption Fourier transform ion cyclotron resonance mass spectrometry have been applied to the determination of non volatile polymer additives (thioester, phosphite, phosphonate and hindered amine antioxidant types) and antioxidants, ultraviolet absorbers and amide waxes. 

Table L Classes of Polymers Studied by Laser Desorption Fourier Transform Mass Spectrometry ...

Figure 1. Comparison of analytical results obtained on an industrial polymer by gel permeation chromatography (top) and matrix-assisted laser desorption ionization mass spectrometry (linear time-of-flight mass spectrometer [center] and Fourier transform mass spectrometer [bottom]). From the FT/MS data the polymer can be identified as a substituted polyethylene glycol.

Several modem analytical instruments are powerful tools for the characterisation of end groups. Molecular spectroscopic techniques are commonly employed for this purpose. Nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy and mass spectrometry (MS), often in combination, can be used to elucidate the end group structures for many polymer systems more traditional chemical methods, such as titration, are still in wide use, but employed more for specific applications, for example, determining acid end group levels. Nowadays, NMR spectroscopy is usually the first technique employed, providing the polymer system is soluble in organic solvents, as quantification of the levels of... 

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