Membrane introduction tandem mass spectrometry and ion-surface collisions in tandem mass spectrometry
Abstract
The difficult introduction of analytes in solutions into a mass spectrometer has resulted in the design of direct insertion membrane probes of both capillary and sheet type. Membrane introduction tandem mass spectrometry is described and analyses at bulk and trace levels are discussed. Volatile molecules in aqueous mixtures are detected at the ppb level using a silicone polymer membrane. The use of these membrane probes and mass spectrometry for fermentor control and environmental analysis is studied. In part two, a novel orthogonal tandem quadrupole mass spectrometer with a surface and a collision cell is described. Polyatomic ion-surface collisions are studied at translational energies between 10-100 eV. Studies with tetraethylsilane molecular ion show striking results. Activation of this ion occurs with an average 16% conversion of laboratory kinetic energy to internal energy in the collision range of 10-100 eV. The refractory polynuclear aromatic hydrocarbon ion pyrene and peptides such as Met-Arg-Phe-Ala, leu-enkephalin and angiotensin fragment extensively. A remarkable SID efficiency of 15% was recorded for Met-Arg-Phe-Ala while typical SID efficiencies for small organic ions are ca. 5%. Reactive additions, chemical sputtering and charge inversions have also been observed. Pyrazine (m/z 80$\sp+$) abstracts a hydrogen atom producing (M + 1)$\sp+$ (m/z 81$\sp+$) as the base peak while the pyrene molecular ion remarkably abstracts five and possibly seven surface carbons. Chemical sputtering is observed for halogenated ions at kinetic energies $>50$ eV and benzene at 200 eV. Charge inversion occurs for C$\sb3$F$\sb5\sp+$, m/z 131$\sp+$, at 30 eV (+ to $-$) and benzoate at 80 eV ($-$ to +). SID is shown to be an excellent means to distinguish four furanocoumarine isomers. Fragmentation of large alkane containing molecules by remote-site fragmentation is shown to be compound dependent. A unique in-line ion-surface collision device was implemented on a QQ and a BEQ mass spectrometer.
Degree
Ph.D.
Advisors
Cooks, Purdue University.
Subject Area
Analytical chemistry
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