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master thesis 04222019 hgMF.pdf (1.43 MB)

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IMPROVING MATRIX DEPOSITION FOR SURFACE LAYER MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME-OF-FLIGHT MASS SPECTROMETRY IMAGING (SL-MALDI-TOF MSI)

Hongming, Guo
http://rave.ohiolink.edu/etdc/view?acc_num=akron155654549756264

Abstract Details

2019, Master of Science, University of Akron, Polymer Science.
The technique of Surface Layer Matrix-Assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry Imaging (SL-MALDI-TOF MSI) shows great potential for characterizing lateral variations in the surface composition of polymer materials. Performing SL-MALDI-TOF MSI requires that a uniform layer of matrix and ionization agent be deposited on the sample before imaging. For the samples studied here the matrix (Trans-2-[3-(4-tert-Butylphenyl)-2-methyl-2-propenylidene] malononitrile or “DCTB”) and ionization agent (silver trifluoroacetate or AgTFA) differ widely in melting point. Signal intensity is poor for samples prepared by the normal sublimation method in which DCTB and AgTFA are sublimated together. This is due to the fact that AgTFA condenses much less on the surface than does DCTB when the temperature chosen is only appropriate for DCTB1. To increase the density of silver ions, sublimating DCTB and ionization agent separately does help. A homogenous matrix layer can be formed on the surface of a polymer thin film by this 2-step sublimation. This method enhances not only the intensity, but also the shot-to-shot stability of signals for imaging. In this research, matrix amount, temperature, and sublimation time have been varied to optimize the sublimation conditions by considering their influence on areal density, thickness, and roughness of the matrix layer. Previous work has shown that if AgTFA is deposited first on the sample surface, polymer under the salt-covered area cannot be detected2. This is due to the fact that polymers need to contact DCTB so that they can receive the energy transferred from it. Therefore, DCTB needs to be sublimated before the salts are. The matrix and salt are deposited quite rapidly at a pressure of 50 mTorr.3. Decreasing the matrix sublimation temperature slows the sublimation and provides a smoother surface. Low temperature is desired for the sublimation as long as the matrix and the salt are adequately condensed. Two kinds of defects have an influence on the quality of MALDI images, large crystals and matrix/ionization agent layers containing two distinct sublayers with no ionization agent in the bottom sublayer next to the polymer. Strategies to avoid these two types of defects are discussed.
Mark Foster (Advisor)
Chrys Wesdemiotis (Committee Member)
86 p.
Polymers

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Citations

  • Hongming, G. (2019). IMPROVING MATRIX DEPOSITION FOR SURFACE LAYER MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME-OF-FLIGHT MASS SPECTROMETRY IMAGING (SL-MALDI-TOF MSI) [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron155654549756264

    APA Style (7th edition)

  • Hongming, Guo. IMPROVING MATRIX DEPOSITION FOR SURFACE LAYER MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME-OF-FLIGHT MASS SPECTROMETRY IMAGING (SL-MALDI-TOF MSI). 2019. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron155654549756264.

    MLA Style (8th edition)

  • Hongming, Guo. "IMPROVING MATRIX DEPOSITION FOR SURFACE LAYER MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME-OF-FLIGHT MASS SPECTROMETRY IMAGING (SL-MALDI-TOF MSI)." Master's thesis, University of Akron, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron155654549756264

    Chicago Manual of Style (17th edition)

akron155654549756264
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© 2019, some rights reserved.Creative Commons License IMPROVING MATRIX DEPOSITION FOR SURFACE LAYER MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME-OF-FLIGHT MASS SPECTROMETRY IMAGING (SL-MALDI-TOF MSI) by Guo Hongming is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Akron and OhioLINK.