A dissertation submitted to the Faculty of Science, University of the Witwatersrand,
in fulfilment of the requirements for the degree of Masters of Science.
Johannesburg, 2017 / The monitoring of personnel for exposure to radioactive elements is a regulatory
requirement for any nuclear installation and due to the nature of the research, the need
for a non-invasive procedure for the monitoring for exposure to plutonium has been
identified at the South African Nuclear Energy Corporation (NECSA). Historically,
analyses of short-lived radioactive elements were performed by α-spectrometry. But
due to the well documented drawbacks of the older generation of α-spectrometer
analysis, Quadrupole Inductively Coupled Mass Spectrometry (Q-ICP-MS) was
suggested as an alternative technique.
A feasibility study was undertaken to determine whether sub-trace concentrations of
plutonium in urine can be determined using a modern, standard Q-ICP-MS. A
simplified One Variable at a Time (OVAT) approach was used to establish optimal
analytical conditions starting from instrument setup and ending in sample
preparation.
The optimum sample preparation determined required 50 mL urine which underwent
co-precipitation, wet-ashing and solid phase extraction using Tetra Valent Actinide
(TEVA)-resin. Calibration standards ranged from 5 to 100 pg L-1 and the optimised
method produced LOD’s of 0.2 pg L-1 and LOQ’s of 0.5 pg L-1. Sample intra-assay
precision at 0.5- and 15 pg L-1 were 11.3% and 4.43% respectively, in the urine
matrix. The bias was 8% and 0% at the same concentrations. The method was
evaluated using samples from an international proficiency study and two out of the
three tests that could be quantified passed specification. According to ISO 13528 a
method is acceptable if two out of three tests pass.
The method has been verified and a modern, standard Q-ICP-MS has been proven to
be a suitable alternative to α-spectrometry with respect to sub-trace plutonium
analysis. / MT 2017
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/23486 |
| Date | January 2017 |
| Creators | Pieterse, Petrus Philippus |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | Online resource (xi, 70 leaves), application/pdf, application/pdf |
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