Thesis-2003-Ingle.pdf (4.84 MB)
Improvements in the accuracy and precision of isotope ratio measurements by double focussing inductively coupled plasma mass spectrometry
thesis
posted on 2013-12-12, 12:19 authored by Christopher P. IngleInductively coupled plasma mass spectrometry is a well-established technique for
the measurement of isotope ratios. Double focussing mass analysers enable
increased resolution to be applied to separate spectroscopic interferences, or the
use of multi-collector detection techniques for high precision isotope ratio
determinations.
For the Central Science Laboratory (CSL), trace elements team, methods were
developed for Zn and Fe isotope ratio measurements in acid digested faecal
samples from a human nutritional study. For Zn, a novel high resolutionlmulticollector
combination was employed; for Fe a single collector, high resolution
method was used. In both cases, samples from the nutritional study known to
contain the analytes in natural isotopic abundance were used to correct for the
mass bias. Two independent methods for determining Zn and Fe isotope ratios
were used to validate the measurement strategies. The team at CSL are also
involved in the authentication of food products. Isotope ratio and elemental
concentration data were used to determine the geographical origin of rice samples,
and to distinguish between traditional and modem Basmati rice grown in India
and Pakistan.
NERC Isotope Geosciences Laboratory are primarily concerned with the
achievable accuracy and precision of an isotope ratio measurement. Use of a mass
bias correction expression appropriate to the ICP-MS instrument is essential for
high quality isotope ratio measurements. Cd and Sn were used to study the
variation of the mass bias in a double focussing ICP-MS system with time,
absolute mass and mass difference. It was proposed that mass bias should be
considered as a result of the change in the instrument response with mass, and not
a fundamental parameter in its own right. A method for determination of the best
mass bias correction model for an individual instrument, through examination of
the instrument response function was developed.
History
School
- Science
Department
- Chemistry
Publisher
© Christopher InglePublication date
2003Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.Language
- en