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Drying Samples
Freeze-dry sample(s) for at least 12 hours before grinding. If the samples still feel cold when removed from the dryer, the samples still have moisture in them and need to dry longer.
The freeze dryer is comprised of a sample "bell" chamber and a Labconco freeze-dryer. On the bell are two valves, as shown in Figure 5. Each valve has an "Open" and "Closed" position. The top valve controls the vacuum inside of the bell, and the bottom valve controls the air flow between the cooling coil and bell. A valve parallel with the tube is open and allows air flow; a valve perpendicular with the tube is closed. In Figure 5, configuration A (closed) will hold a vacuum, but configuration B (open) will not.
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Figure 6. Freeze dryer control panel.
Grinding Solid Samples
There are three primary ways to grind samples:
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Mortar and pestle is the most common method. Below, each method is outlined.
Drying Samples
Freeze-dry sample(s) for at least 12 hours before grinding. If the samples still feel cold when removed from the dryer, the samples still have moisture in them and need to dry longer.
The freeze dryer is comprised of a sample "bell" chamber and a Labconco freeze-dryer. On the bell are two valves, as shown in Figure 5. Each valve has an "Open" and "Closed" position. The top valve controls the vacuum inside of the bell, and the bottom valve controls the air flow between the cooling coil and bell. A valve parallel with the tube is open and allows air flow; a valve perpendicular with the tube is closed. In Figure 5, configuration A (closed) will hold a vacuum, but configuration B (open) will not.
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Figure 6. Freeze dryer control panel.
Grinding Solid Samples
There are three primary ways to grind samples:
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Cleaning the Vessels
Clean the grinding vessels with a toothbrush and DI water. In some cases the vials are still dirty or have sample stains on them. If so, take a small amount, approximately 5 mL, of silica sand and grind it in the mixer mill for ~3 minutes. Then pour out the sand and clean the vessel with DI water and a toothbrush or Greenie Meanie. Lay out cleaned vessel parts on a Kim Towel and dry with a Kim Wipe. The cork rings take a longer to dry, so collect fresh, dry rings before grinding the next sample.
Then can now pack the samples.
Retsch MM400 mill
Figure 16: Retsch MM400
Grinding Jar
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