Flow injection methods of sample introduction for ICP-MS

Nelms, Simon

Chemistry
September 1997

Thesis or dissertation


Rights
© 1997 Simon Nelms. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.
Abstract

This thesis is concerned with the application offlow injection techniques for on-line sample preparation for inductively coupled plasma mass spectrometry (ICP-MS). A comprehensive introduction to ICP-MS and the various sample introduction methods which have been applied for the technique is presented in Chapter 1. The advantages and disdvantages of the different sample introduction procedures are also considered and discussed. Since ICP-MS is a highly sensitive technique for multi-element analysis at trace levels, there are few methods which can compete with it. The methods which are available are compared with ICP-MS and the advantages and disadvantages of each are discussed in the context of the available literature.

The second chapter contains a detailed review of the various reagents which have been used for the selective retention of trace element ions from solutions containing high concentrations of so called 'matrix species' (e.g. Na, Ca, K and Mg). The use of ion-exchange and chelating reagents for trace analyte retention is discussed together with an appraisal of the properties and applications of activated alumina as either a cation or anion exchanger. Most ion-exchange and chelating reagents consist of an organic functional group covalently immobilised onto a support material. The properties of polymer and controlled pore glass support materials are discussed with respect to their behaviour in on-line systems.

In Chapter 3, the use of the chelating reagent 8-hydroxyquinoline, covalently immobilised onto controlled pore glass, for on-line preconcentration and matrix separation with ICP-MS detection, is described. A manually operated manifold, directly coupled to the ICP-MS, was developed for this work. The optimisation and analytical performance ofthis manifold is evaluated for Ti4+, V (as VO2+), Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Ag+, Cd2+, Ce3+ and Pb2+ in saline matrix samples and reference materials. Following the development of the manual manifold described in Chapter 3, the construction of an automated preconcentration I matrix separation manifold, using a commercially available liquid handling system is described in Chapter 4. For this work, a novel iminodiacetate chelating reagent, immobilised onto a controlled pore glass support, was used for analyte retention. An initial manifold design is considered, followed by a refined version of the system, which is optimised for the retention of Mn2+, V (as VO2+), Co2+, Ni2+, Cu2+,Zn2+, Ag +, Cd2+, Ce3+, Pb2+ and U (as UO2+). The performance of the novel iminodiacetate chelating material is evaluated for the analysis of two saline reference waters and some saline industrial effluent samples.

In Chapter 5, the effects of humic material in the sample on the on-line retention of Ti4+, V (as VO2+ ), Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Ag+, Cd2+, Ce3+, Pb2+ and U (as UO2+) by the iminodiacetate reagent is explored. Humic material, which arises from soil and decaying vegetable matter, exists in fresh and saline waters at concentrations of typically 1 - 50 ppm. This complex material is composed of a number of different organic molecules which contain a variety of functional groups capable of forming chelates with the analytes of interest in the sample. For this reason, interference effects are expected to occur with increasing levels of humic material in the sample. The effect of increasing levels of elements which have an affinity for the iminodiacetate reagent is examined in terms of the retention efficiency of the analytes of interest.

In Chapter 6, the subject of microwave digestion for sample preparation is studied. This work initially involves assessing the efficiency of a simple nitric acid digestion for the digestion of selected reference materials in a batch system. The study continues with an evaluation of on-line microwave digestion with off-line analysis using ICP-MS and concludes with an investigation into the feasibility of directly coupling the on-line
microwave digestion system to the ICP-MS instrument. Finally, in Chapter 7, the general conclusions to the thesis and suggestions for future research are presented.

Publisher
Department of Chemistry, The University of Hull
Supervisor
Greenway, Gillian M.
Sponsor (Organisation)
VG Elemental
Ethos identifier
uk.bl.ethos.389435
Qualification level
Doctoral
Qualification name
PhD
Language
English
Extent
11 MB
Identifier
hull:16060
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