Mass spectra of polymers

SFC-based methods still need to show their potential, in spite of past great promise. pSFC-APCI-MS is a powerful method for identification of polymer additives, provided that a library of mass spectra of polymer additives using this technique is available. SFC-MS appears less performing than originally announced nevertheless, SFE-SFC-EIMS is an interesting niche approach to additive analysis. On the other hand, we notice the lack of real breakthrough in SFE-SFC-FTIR. 

Proof of the presence of macrozwitterions comes from end group analysis and mass spectroscopic measurements. Both triphenyl- and tricyclohexylphosphoniomethylides yield polymers with one phosphorus atom per chain. In the mass spectra of polymers initiated by triphenylphosphonio methylide (but not BuLi), fragments are found with high m/e-values characteristic of degradation products from triphenylphosphine and phosphine oxide. 

Polymers from Thiophens. - The mass spectra of polymers... 

Statherojxjulos, M., Georgakopoulos, K., and Montaudo, G., The Interpretation of Mass Spectra of Polymers Using a Hybrid Software System Based on Library Searching with Euristic, /. Atml. Appl. Pyrolysis, 20, 65 (1991). 

Lattimer, R. P. and Welch, K. R., Field desorption mass spectra of polymer chemicals. Rubber Chem. Technol, 51, 925, 1978. 

The most serious problems encountered in achieving correct estimates of the molar masses of polymers from their MALDI-TOF spectra do have an instrumental origin. For the quantitative analysis of mass spectra of polymers, the number of charged adducts revealed by the MS detector must reflect the number of polymeric chains actually existing in the sample. This requires that the ionization yield of the various oligomer species present in polymers must be independent of chain size, and that the MALDI-TOF detector ought to show a constant response to ions as the mass of the oligomer increases. 

PCA had been employed to characterize the SIMS mass spectra of polymers and biomolecules [39,50]. PCA has also been applied to the interpretation of TOF-SIMS spectra of proteins and extended the application of TOF-SIMS measurement to biomaterials. The schematic of the procedure of PCA is shown in Figure 11.4. Prior to analysis, several peaks are selected from each spectrum. Normalization and pretreatment of the data are sometimes necessary to assure that the variance patterns highlighted are truly related to the chemical differencesbetweenthesamplesandnotmathematical differences in peak intensities. A typical data set X with m samples and n peaks then can be written as a matrix, with m rows and n columns. These are transformed into PCs by multiplication of the appropriate matrix. The... 

In the mass spectrum of the poly(m-phenylene sulfide) (polymer I, Figure 5.9a), the peaks at m z 324 + nl08 correspond to molecnlar ions (M ) of cyclic oligomers M3+-M13+. FAB mass spectra of polymers II-IV in Figure 5.9 (parts b-d, respectively), show peaks due to protonated molecular ions (MH ) of the oligomers present in mixtnres. 

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