METTLER TOLEDO has crucibles to meet every need. We will show the preparation of a DSC sample using a 40 µL standard aluminum crucible and a 100 µL aluminum crucible as examples.
The samples are powder samples and suspensions. For DSC sample preparation, you will need.
A microbalance, placed on a stone table
Crucible box with crucible
Crucible sealing press
Laboratory log
Samples
DSC measurements are performed using reference and sample crucibles, each with a lid. For good measurement results, the difference in weight between the sample and the crucible/lid combination on the reference side should not exceed 0.2 mg.
We start with the preparation of the powder sample. The lid is placed on a rubber and two holes are punched in the lid of the reference crucible using the punching needle in the crucible box, and then one hole is punched in the lid of the sample crucible.
The crucible and lid are placed on a balance for weighing the tare. Place the funnel from the crucible box on the crucible and place approximately 10 mg of powder with a small spoon. The funnel will ensure that the sample does not spill over the edge of the crucible and remove the funnel. Close the weighing chamber and allow the balance to stabilize. Read the weight displayed on the balance and make a note of this data in the lab log.
Use the crucible press to seal the crucible. Place the crucible on the press tray, close the crucible lid, center the crucible, and rotate the lever to move the plunger down until no further downward pressure is possible. The lid is now cold welded to the edge of the crucible.
When preparing liquids in a 100 µL aluminum crucible, we use the received lid to seal the crucible. In a humid environment, the crucible and lid can be left in a desiccator overnight in order to prevent the crucible from reacting with water. Subsequently, the aluminum surface will be passivated.
After weighing the tare, the liquid from the aqueous suspension is injected into the crucible using a syringe. To avoid problems with thermal expansion, the liquid injected should not exceed half of the crucible volume. The sample will evaporate as soon as the crucible is opened, so the operation should be rapid.
Cold weld the lid to the crucible and verify the weight again. Let it sit on the balance for a while. If the weight does not decrease by more than 20 µg in five minutes, the crucible is well sealed. Record the weight in the laboratory log.
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