give efficient extraction. Since water polarity is much higher 
than that of octanol, the partitioning model clearly infers the 
need to remove water before attempting the extraction of neutral 
organic compounds. 
This approach differs considerably from the conventional 
Soxhlet extraction procedure applied to wet sediment. The lat¬ 
ter also requires large solvent to sample ratios so an extra 
burden is implied in terms of needed solvent purity. We were 
advised by Dr. George Boughman (personal communication) that 
Soxhlet extraction tends to be incomplete due to slow diffusion 
of solvent through the sediment sample. For that reason, a thin 
coating of sediment is advised to line the extraction thimble. 
Unfortunately, this procedure boosts the solvent-to-sample ratio 
even further. 
Sediment Extraction with Methylene Chloride 
1. Two grams of sediment is weighed to the nearest mg 
and placed in 10 ml capacity vials with Teflon 
lined caps. The caps are screwed on tightly to 
prevent evaporation. 
2. Five ml of methylene chloride, containing 0.40 ppm 
dimethoxyethyl phthalate (DMEP) as internal standard, 
is introduced using a Repipet apparatus. (A different 
amount of DMEP was used for the Tenneco Pong sample. 
This involved 4.0 ppm DMEP in CE^Cl^, but there was no 
subsequent evaporation.) 
3. The vials are first agitated in a Vari-whirl mixer to 
suspend the particles. 
4. The vials are placed in an ultrasonic bath. Circu¬ 
lating water is used to hold a temperature of ap¬ 
proximately 30°C for 2 minutes. 
5. The vials are centrifuged at 2,500 G for 15 min. 
This is done to remove suspended particles. 
6. The supernatant liquid is drawn off and placed in 
a 5 ml capacity vial using a Pasteur pipet. 
7. The extract is evaporated under a stream of purified 
nitrogen to a volume of approximately 0.5 ml. The 
nitrogen is purified by passing through a column of 
carefully extracted washed (Chester et al. 1976) 
XAD-2 resin. 
51 
