Novel in situ mass spectrometric analysis for biological applications using ambient ionization methods
Abstract
The development of ambient ionization methods brings innovation in mass spectrometry (MS) with the capability to analyze samples in their native environment, without sample preparation or pre-separation by creating ions outside the instrument. The objective of the research described in this thesis is to develop novel biological applications of different ambient ionization methods. ^ The first research project is to apply desorption electrospray ionization (DESI) MS analysis for in situ bacterial differentiation based on their lipid mass fingerprint patterns. ^ The next three research projects using low temperature plasma (LTP) ionization mass spectrometry reveal the unique capabilities of LTP ionization method, and demonstrate its promising future for novel biological applications. Rapid in situ bacterial differentiation based on their fatty acid ethyl ester (FAEE) profiles was achieved by LTP-MS. Facile determination of double bond position(s) in unsaturated fatty acids and esters is also accomplished by directly applying LTP probe on untreated mono/polyunsaturated samples. In the described third application of LTP-MS, a convenient pyrolysis device was designed to work in the open atmosphere enviorments. It was coupled with LTP-MS to perform rapid bacterial biomarker detection (dipicolinic acid in Bacillus endospore). ^ The last two research projects focus on leaf spray, a new developed ambient ionization method derived from paper spray ionization method. The bright future of leaf spray analysis in the agriculture and food industry can be seen from these two demonstrated applications: the direct analysis of glycosides from fresh stevia leaves for sugar substitute market research, and the in situ analysis of live bacteria cells directly from vegetable leaves for current food safety issues.^
Degree
Ph.D.
Advisors
Robert G. Cooks, Purdue University, Weiguo A. Tao, Purdue University.
Subject Area
Chemistry, Analytical|Chemistry, Biochemistry
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