Mass spectrometry of polymers and polymer surfaces.

Size-exclusion chromatography-a review of calibration methodologies.

Ion mobility and mass spectrometry techniques, combined with electrospray ionization, have been used to examine distributions of poly(ethylene glycols) (PEG) with average molecular masses of 6550 and 17900 Da. The analysis provides information about the polymer size distributions as well as smaller oligomers existing over a wide range of charge states and sizes (i.e., [HO(CH2CH2O)xH + nCs]n+, where x ranges from 21 to 151 and n = 2 to 11 for the 6550 Da sample; and, x ranges from 21 to 362 and n = 2 to 23 for the 17 900 Da sample). The present data show that oligomer distributions also fall into families, corresponding to much narrower size distributions for individual charge states; this dramatically simplifies data analysis. For example, we show evidence for baseline resolution of the +10 charge state of polymers. Unlike the charge-state trends reported previously for peptide ion families, which show generally increasing mobilities with increasing charge state (for a given m/z value), the mobilities of ...

Resolving oligomers from fully grown polymers with IMS-MS.

The design of efficient radical photoinitiating systems requires a systematic and detailed evaluation of their photochemical characteristics. Correlating absorbance and the corresponding electronic transitions of a photoinitiator is critical for understanding its photoinduced reaction pathways. In the current contribution, we provide an in-depth investigation into the photochemistry and photophysics of two oxime ester derivatives (O-benzoyl-α-oxooxime, OXE01, and O-acetyloxime, OXE02), known for their excellent performance in pigmented formulations. In particular, we shed light on their wavelength-dependent photopolymerization properties. We utilized a combination of UV–vis spectroscopy, density functional theory (DFT) calculations, photochemically induced dynamic nuclear polarization spectroscopy (photo-CIDNP), and pulsed-laser polymerization with a wavelength-tunable laser with subsequent size exclusion chromatography coupled to high-resolution electrospray ionization mass spectrometry (PLP-SEC-ESI-MS) ...

Wavelength-Dependent Photochemistry of Oxime Ester Photoinitiators

We report on the successful application of size exclusion chromatography (SEC) combined with electrospray ionization mass spectrometry (ESI-MS) and refractive index (RI) detection for the determination of accurate molecular weight distributions of synthetic polymers, corrected for chromatographic band broadening. The presented method makes use of the ability of ESI-MS to accurately depict the peak profiles and retention volumes of individual oligomers eluting from the SEC column, whereas quantitative information on the absolute concentration of oligomers is obtained from the RI-detector only. A sophisticated computational algorithm based on the maximum entropy principle is used to process the data gained by both detectors, yielding an accurate molecular weight distribution, corrected for chromatographic band broadening. Poly(methyl methacrylate) standards with molecular weights up to 10 kDa serve as model compounds. Molecular weight distributions (MWDs) obtained by the maximum entropy procedure are compar...

Quantitative LC-MS of polymers: determining accurate molecular weight distributions by combined size exclusion chromatography and electrospray mass spectrometry with maximum entropy data processing.

We report an on-line coupling of gel permeation chromatography (GPC) to Fourier transform mass spectrometry (FTMS) using a modified commercial electrospray ionization (ESI) interface. Selected oligomer profiles for the sodiated (1+ through 5+ charge states) oligomer ions of a narrow-molecular-weight poly(methyl methacrylate) were generated and used for obtaining a calibration curve. Using the MS-generated calibration curve and the refractive index response for quantification, an accurate molecular weight distribution was calculated and showed an excellent agreement with the value specified by the supplier. GPC/ESI/FTMS also allowed for an unequivocal end-group determination and characterization of a secondary distribution due to the formation of cyclic reaction products. We analyzed a glycidyl methacrylate/butyl methacrylate copolymer with a broad molecular weight distribution, where fractionation and high resolving power were required for adequate characterization. Molecular weight distribution data show...

David J Aaserud

Papers

Gel permeation chromatography coupled to fourier transform mass spectrometry for polymer characterization.

Microcolumn size-exclusion chromatography coupled with electrospray ionization mass spectrometry.

Modern mass spectrometry for coatings