The analysis of organometallic compounds using SFC-ICPMS.

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.