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Coastal and Marine Geology Program
Woods Hole Field Center

Geochemical Sediment Analysis Procedures, Open-File Report 02-371

CENTRIFUGE STEP


CENTRIFUGE STEP
Materials Required:
  • Deionized Water (18.2 megohm - cm at 25°C) also called Milli-Q
  • Centrifuge Tubes Containing Sediment, H2O2, and HCl
  • 10mL Pipet
  • Balance
  • Vortex Mixer
  • Centrifuge
 Preparation materials for centrifuge step; link to larger image
Tare the balance with a centrifuge tube and a beaker to hold the tube upright. Tare balance with tube; link to larger image
Using a 10mL pipet, add 20 mL of Milli-Q water to the centrifuge tube. Pipet Milli-Q into tube; link to larger image
Record the weight of the tube, liquid, and cap. Weighing vial, liquid, and cap; link to larger image

Vortex samples until sediment is uniformly suspended.

Weigh vials first to ensure you place similar weights opposite each other in the centrifuge.

 Vortexing sample; link to larger image

Load samples into centrifuge.

*Samples directly opposite each other should have similar weights within 0.1g.

Place samples in centrifuge; link to larger image
Centrifuge at 2400 rpm for 5 minutes. Turn on centrifuge; link to larger image
Swirl samples until residual sediment is removed from the sides. Swirling sample; link to larger image
Centrifuge at 2400 rpm for 5 minutes. Centrifuge again; link to larger image

Pipet off and discard the supernatant using 10mL pipet.

*Leave the last 1/4 inch of liquid to avoid disturbing sediment.

Proceed to oven drying step.

 Pipet off the supernatant; link to larger image

 

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