Blake, Earl.
Abstract:
Supercritical fluid chromatography has recently been coupled to an ICPMS
detector. The method has been shown to be suitable for the speciation
and analysis of organometallic compounds at trace levels. This study has
attempted to further the research initiated by other groups in this field by
developing a new interface for coupling these two instruments. The new
interface makes use of a modified join between the nebuliser and the torch
in the ICP unit. The effect of the mobile phase on the plasma with time
has been investigated and little spectral background interference has been
observed.
The chromatographic conditions were optimised using a flame ionisation
detector and a series of tin, arsenic, iron, and mercury compounds were
analysed using SFC-ICPMS. Mter focusing the ICP-MS on the element of
interest, each compound was evaluated in terms of the change in peak
intensity with change in concentration and the theoretical detection limits
were compared to the practical detection limit.
The restrictor temperature was determined using a rough calibration
procedure with bench top experiments. The effect of the restrictor
temperature on the peak intensity of each compound was then studied. All
results were plotted and a theory for the observed trends and observations
is proposed. The results obtained and the interface used have been
compared to the results and interfaces of other groups and differences
have been explained. Attempts to extract relevant compounds from topsoil
using supercritical fluid extraction were made.
Finally, sediment samples were collected from relevant points in Durban
Bay and an attempt was made to extract these samples using supercritical
fluid extraction. The extracted samples were analysed using SFC-ICPMS
although little success was obtained. Reasons for the failure of this
method on the real samples have been proposed. In the concluding section
of this study SFC~ICPMS has been evaluated in terms of its future
applicability and use as a viable analytical method.
