Soxhlet extraction procedures are as follows: 
Wet Soxhlet Procedure 
1. The extraction thimble 43 x 123 mm was extracted 
with methylene chloride for 24 hours before use. 
2. A clean 2000 ml flask was charged with 500 ml of 
methanol containing approximately 5 pg of the 
internal standard, d-10 anthracene ( C ]_ 4 D io) * 
3. The thimble was loaded with approximately 90 g 
of wet sediment (60 percent moisture content). 
The sediment was smeared onto the walls of the 
thimble cylinder to provide more intimate con¬ 
tact with the solvent. 
4. After 24 hours the methanol was emptied into a 
storage container and replaced by 500 ml methylene 
chloride and an additional 5 pg of d-10 anthracene. 
5. The extraction was continued for at least 48 hours, 
when the extract solution in the thimble chamber 
became completely clear. 
6. The solvents were distilled off using Buchi Roto- 
vapor R. until approximately 30 ml of aqueous 
extract remained. 
7. This aqueous liquid was extracted with 5 volumes 
of methylene chloride. This extract was concen¬ 
trated to 5 ml using the Rotovap. Further 
evaporation was done using a stream of nitrogen 
(XAD-2 filtered). 
8. A blank was prepared by duplicating the procedure 
described above, but without the sediment samples. 
Dry Soxhlet Extraction —This procedure is the same as the 
wet Soxhlet extraction procedure except for the following modi¬ 
fications . 
1. The sediment was first dried by desiccation to a 
moisture content of 1-2 percent. 
2. Approximately 40 g of dried sediment was added to 
the previously extracted thimble. 
3. Only methylene chloride was used as extracting 
solvent and the extraction duration was 72 hours. 
66 
