Gill, Matthew Clive (2010) The ion conveyor : an ion focussing and conveying device for mass spectrometry. PhD thesis, University of Warwick.

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Abstract

The advent of electrospray ionisation (ESI) has been a major factor driving the
revolution which has taken place in the field of biological mass spectrometry over
the past twenty years. In this thesis, efforts to improve electrospray ionisation in
two respects are detailed. One is the transmission of ions from ambient pressure
into the high vacuum of a mass spectrometer. The other is control and influence
over making and breaking of bonds, in particular long and weak bonds, during
this journey into the mass spectrometer.
These improvements to electrospray ionisation have been sought through the
development, theoretical analysis and application of the ion conveyor, which is an
electrodynamic ion-transport device. The ion conveyor as reported here is a
device consisting of stacked ring-electrodes intended for operation within the first
and second differential-pumping regions of a mass spectrometer with an
electrospray ionisation source. It is demonstrated how the ion conveyor achieves
aspects of ion trapping and ion transport through the application of one or more
radiofrequency waves to the stacked ring-electrodes. The operating principles of
the device are detailed, and related technologies are described. Theoretical
simulations have been used to explore for explanations for the behaviour of the
device and to make predictions as to the optimum performance of the device.
The first experiments with an ion conveyor and subsequent experiments with two
evolved designs are described. The operation of the device has been
investigated with three different types of mass spectrometer, each with its own
design of electrospray ionisation source. These designs are described in detail,
and the responses of the ion conveyor to various operating parameters have
been characterised. A major finding was that the transmission of the ion conveyor
remains significantly high in the absence of all applied potentials. This discovery
reveals and emphasises the importance of mechanical forces to ion transport
through the ion conveyor.
A wide variety of analytes have been used in experiments to characterise the
device. The mass spectra of vancomycin hydrochloride presented are of
particular note, because they exhibit unusually intense peaks corresponding to
the doubly charged dimer-species. The dimer of vancomycin plays the central
role in long-standing theories of anti-bacterial action, but has not been observed
in previous studies of vancomycin by mass spectrometry.
The experimental results support the view that the ion conveyor is a useful
technique for the effective transport of ions through the differential-pumping
stages of an electrospray ionisation source. The results suggests that the device
could be developed through appropriate manipulation of ion-neutral collisions in
the higher-pressure regions to preserve and transmit delicate non-covalently
bound species and facilitate their accurate measurement by means of mass
spectrometry.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Electrospray ionization mass spectrometry
Official Date:	February 2010
Dates:	Date Event February 2010 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Derrick, Peter
Extent:	xiv, 227 leaves : ill., charts
Language:	eng

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