Reactive desorption electrospray ionization mass spectrometry for in situ detection of non-polar molecules and its applications in chemical imaging
Abstract
To extend the capabilities of desorption electrospray ionization (DESI), in situ reactions were developed and used in DESI to enhance the selectivity and sensitivity for the detection of compounds with low polarities. Rapid and quantitative analysis of less-polar molecules such as endogenous cholesterol in human serum was successfully implemented under ambient conditions. Reactive DESI imaging of biological tissues was also demonstrated. In addition, discharge-induced oxidation in DESI was studied and used as an in situ derivatization method for sensitive ambient analysis of saturated hydrocarbons without any functional groups. DESI MS imaging was utilized to explore the distribution of small hormones and antioxidants in the adrenal, and the results were compared with traditional histochemical methods. The high sensitivity of mass spectrometry and specificity of tandem MS combined with high resolution mass spectrometry, extend the information provided by DESI imaging. In the last part of the dissertation, the reactivity of pyridinium molten salts in atmospheric-pressure thermal desorption ionization (APTDI) was studied. Spectra were recorded by simply heating pyridinium molten salts in front of a mass spectrometer under atmospheric pressure. Source of the factors affecting the reactivities of pyridinium salts and their thermal degradation pathways were elucidated.
Degree
Ph.D.
Advisors
Cooks, Purdue University.
Subject Area
Analytical chemistry
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