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It was also shown that the carbon dioxide containing 5% methanol was more efficient for extracting the
tin chelates than carbon dioxide alone. Furthermore, the extraction efficiency was also shown to
increase with the supercritical fluid pressure. Increasing the pressure also reduced the amount of water
extracted and increased the necessary extraction time. Increasing the temperature from 60°C to 100°C
did not appear to change the extraction efficiency significantly one way or the other. The use of a
complexing reagent was essential to achieve high recoveries.
Emteborg et al. [9] also employed a supercritical extraction procedure followed by a GC/AS analysis to
develop a method for assaying mercury in sediments. 0.5-1 g of sediment was placed in the extraction
thimble and diluted with clean sand and extracted with liquid carbon dioxide.
Figure 6.9
GC-MIP-AES Chromatograms from
Standard Sediment Samples Monitored
on the Mercury Channel (ref. 9)
The extract was depressurized in a ODS trap and the methylmercury eluted from the trap with toluene.
The toluene extract was then placed in a
