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Detection of Oxidized Lipids by Laser Desorption Ionization Time of Flight Mass Spectrometry Using Hydrazine Containing Reagents

Alyami, Mohammed Abdullah A
http://rave.ohiolink.edu/etdc/view?acc_num=mco1525430246975348

Abstract Details

2018, Master of Science in Pharmaceutical Science (MSP), University of Toledo, Pharmaceutical Sciences (Pharmacology/Toxicology).
Since matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was established, it has been advanced as an analytical technique to detect and identify a large range of molecules. Lipids have been analyzed intensively by MALDI-TOF MS for several years. Because lipids are essential components of the body, any change in their structures can produce dramatic effects, either beneficial or detrimental. Oxidation of phospholipids is one of these types of changes. In the brain, it is found that formation of amyloid fibrils has a strong relationship to production of oxidized phospholipids (OxPLs) such as 1-palmitoyl-2-(9-oxo-nonanoyl)-sn-Glycero-3-phosphocholine (PoxnoPC). Due to addition of an aldehyde group in oxidized lipids, it may be possible to selectivity detect them by using fluorescent reagents containing a hydrazine functional group which was the ability to react with the carbonyl group. In the context of the MALDI-TOF MS analysis technique, 2,4-dinitrophenylhydrazine (DNPH) has been used as a reactive matrix holding the promise that this might allow selective detection oxidized lipids among un-oxidized lipids. However, in these studies unreacted excess DNPH was never removed, preventing definitive conclusions to be made as regarding the role of DNPH as a fluorescent tag as opposed to functioning as a matrix. Oxidized phosphatidylcholine is derivatized at its carbonyl group with DNPH to form 2,4-dinitrophenylhydrazone (DNPhydrazone). To evaluate the “reactive matrix” concept implying that DNPhydrazone might be used as a selective detection of the analyte, we removed an excess amount of unreacted DNPH by using glyoxylic acid (GA) and added back different concentrations of DNPH. We found that the signal of DNPhydrazone was directly proportional to the DNPH concentration. Moreover, signals for both 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) mixed with DNPH were detected. DNPH functioned as a non-reactive matrix molecule as well as an analyte tag, although DNPhydrazone demonstrated a higher signal than DPPC in all experiments. Utilizing DNPH as a matrix molecule, we examined the difference of laser power required for compared with 2,5-dihydroxybenzoic acid (DHB). In the presence of DNPH, our results showed that DPPC needed lower laser intensity to be recorded. In contrast, DHB required more energy for detection of DPPC. Interestingly, we observed that a complex mixture of lipids influenced the DNPhydrazone and DPPC signals significantly. Further experiments showed that although DNPH did not allow matrix-free detection of oxidized lipids and was not selective in positive ion mode, selective detection of oxidized lipids is possible in negative ion mode. Here, DNPH appears to act as a charge-tagging reagent, adding a negative charge to the hydrazine moiety of DNPH.
Hermann Grafenstein (Committee Chair)
59 p.
Analytical Chemistry; Chemistry

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Citations

  • Alyami, M. A. A. (2018). Detection of Oxidized Lipids by Laser Desorption Ionization Time of Flight Mass Spectrometry Using Hydrazine Containing Reagents [Master's thesis, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=mco1525430246975348

    APA Style (7th edition)

  • Alyami, Mohammed. Detection of Oxidized Lipids by Laser Desorption Ionization Time of Flight Mass Spectrometry Using Hydrazine Containing Reagents. 2018. University of Toledo, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=mco1525430246975348.

    MLA Style (8th edition)

  • Alyami, Mohammed. "Detection of Oxidized Lipids by Laser Desorption Ionization Time of Flight Mass Spectrometry Using Hydrazine Containing Reagents." Master's thesis, University of Toledo, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=mco1525430246975348

    Chicago Manual of Style (17th edition)

mco1525430246975348
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© 2018, some rights reserved.Creative Commons License Detection of Oxidized Lipids by Laser Desorption Ionization Time of Flight Mass Spectrometry Using Hydrazine Containing Reagents by Mohammed Abdullah A Alyami is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Toledo Health Science Campus and OhioLINK.