Extraction of Biomarkers from Sediments - Accelerated Solvent Extraction

1. Collection of the Necessary Materials

1. Extract samples. Samples (in this case, sediment) are frozen, freeze-dried, crushed, and homogenized prior to extraction, and extracted in groups to maximize efficiency.
2. Depending on the size of the sample, use collection vials with volumes of 40 or 60 mL. For this experiment, borosilicate glass vials (40 mL) and solvent safe caps are used. Combust vials, borosilicate glass pipettes, and weighing tins at 550 °C for 6 h prior to ensure removal of possible organic contaminants.
3. Dichloromethane (DCM) and methanol are common in most organic geochemistry laboratories. Use them individually, (methanol first, followed by DCM) to rinse lab tools and glassware before use. A mixture of dichloromethane to methanol (MeOH; 9:1) is used in many labs to efficiently extract biomarkers with a wide range of polarities. Solvents should be free of organic contaminants.
4. Obtain an Accelerated Solvent Extractor to use for this experiment.

2. Preparation of Sample Cells

1. Assemble a sample cell for each sample to be extracted, plus one blank.
   1. For each cell, screw an end cap onto one end of the cell body.
   2. Place a combusted glass fiber filter on top of each cell using solvent-rinsed tweezers. Then, gently and slowly press the filter down into the cell using the filter plunger.
   3. Label the cell bodies by number (e.g. 1 - 22) for each sample and write "blank" on the blank cell.
   4. Fill the blank with diatomaceous earth (or sand) and cap with a second end cap. Tighten by hand.

3. Preparation of Samples

1. Place a combusted weighing tin on the lab scale and then tare.
2. Rinse the lab spatula with solvent, then use it to transfer an appropriate mass of sample into the weighing tin, and record the mass.
   1. The mass of the sample varies depending on its organic matter content. Relatively organic matter lean material (marine mud) may require several grams, while organic matter rich material (leaf tissue) may require much less.
3. Transfer all of the material in the weighing tin into a prepared ASE cell.
4. Place another glass fiber filter onto the top of the cell, then slowly and gently press down until it reaches the top of the sample using the filter plunger.
5. Add diatomaceous earth (or sand) to the cell until it is almost full. Be careful to remove any debris from the cell body threads.
6. Cap the top of the cell with another end cap.
7. Repeat steps 3.1 - 3.6 for each sample.

4. Preparation of Collection Vials

1. Label each vial with the number of a corresponding cell (e.g. 1 - 22 or blank) and cap with ASE collection vial cap.

5. Extraction

1. Place each sample cell into a numbered slot on the upper ASE tray.
2. Place the corresponding collection vial in the same number slot on the lower ASE tray.
3. Create the extraction method using the keypad on the ASE. Extract at 100 °C and 1,200 psi. Extract each sample 3x with a static hold of 10 min and flush the cell body with 50% of its total volume between static holds.
4. Make sure the solvent bottle contains enough solvent to extract all of the samples.
5. Rinse the ASE 3x before starting the run by pushing the "rinse" button on the ASE control pad.
6. Press start.