ACCELERATED SOLVENT EXTRACTION ONE-STEP CLEANUP

ERDC TN-DOER-C10

March 2000

Activate silica gel by oven drying for at least 24 hr at 130 C.

Tare a 1-L glass bottle. Fill the bottle approximately two-thirds full with oven-activated

silica gel.

Calculate two-thirds of the weight of silica gel; place this amount of concentrated

sulfuric acid in the bottle.

Cap with a Teflon-lined screw cap and shake vigorously until there are no lumps and

the contents exhibit a dry, powdery appearance.

Tumble on a bottle roller for a minimum of 2 hr.

Label the bottle with date prepared and store at room temperature. The maximum

shelf life of SA/SG is 6 months, after which the unused portion should be discarded.

IV. ACCELERATED SOLVENT EXTRACTION ONE-STEP CLEANUP.

Accelerated Solvent Extraction utilizes heat and high pressure to extract compounds such as

polychlorinated biphenyls, polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides,

organophosphorus pesticides, polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans,

and other common contaminants from environmental samples. However, to obtain a response in

cell-based assays based solely on the dioxin and dioxinlike compounds, PAHs and polar compounds

present in the crude extract must be removed. This is typically accomplished by passing the crude

extracts through a separate SA/SG column after extraction by ASE, Soxhlet, or sonication

techniques. In the one-step ASE method, the ASE extracting vessels/cells are packed with neutral

silica gel (SG) and SA/SG before the contaminated sediment is placed in the cells. By extracting

the sediment and cleaning the extract in one step, this method significantly reduces time and

solvent-related expenses without sacrificing extraction or cleanup efficiency.

PACKING AND CONDITIONING THE CELL COLUMN.

Caution! Always wear dust mask, safety glasses, and gloves while working in

ventilated hood.

1) Place one end cap onto the ASE extraction cell opposite the end with the serial

number, tightening by hand (do not overtighten). It is important to place the cap

on the proper side in order to keep track of how the cell was loaded; if the cell is

placed on the ASE in the wrong direction, the extract will not pass over the

SA/SG and will not be cleaned.

2) Place one cellulose filter in the open end of the cell, and using the dowel, push the

filter snugly against the cell cap.

3) Add 2 g Ottawa Sand to cover the filter.

4) Add 2 g neutral SG followed by 8 grams SA/SG and tap with a small rubber mallet

to pack the column tightly.

5) Firmly clamp the cells in a lab stand situated in a ventilated hood. Place a beaker

under each cell to collect waste solvent. Carefully remove the end cap (the

cellulose filter will keep the packed column in place) and add 80 mL hexane per