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Rock samples are crushed to a fine, talc-like powder using multiple cleaning, crushing and grinding procedures. After grinding, loss on ignition (LOI) is determined. Ignited material is fused with flux powder forming a glass sample bead. Fused beads are then dissolved in 10% HNO3 . This is further diluted and the resulting solution is processed by the ICP-OES machine.
The complete process (from sample table to ICP-OES machine) takes 3-4 days. :
- Day 1 involves: polishing on the Diamond Wheel, cleaning, and drying samples overnight.
- Day 2: Crushing in the X-Press, grinding in the Shatterbox, a pre-ignition (for LOI) weight, and placing samples in the muffle furnace overnight.
- Day 3-4: Taking a post-ignition (for LOI) weight, and fusing the sample bead. The beads are handed off to the chemistry technicians to continue ICP analysis.
Wait until there are about six or more samples so you can prepare a 'batch' of six or more at a time.
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- Splitting room saw
- Buehler grinder/polisher with 70 µm grit diamond grinding wheel
- Sonicator (with small water bath)
- X-Press crusher
- Spex Shatterbox with tungsten carbide (WC) grinding vessel
- Spex Mixer Mill with tungsten carbide or alumina canisters
- Retsch MM400 Mixer Mill
LOI/Bead-Making
- Fisher Ashing muffle Furnace
- Sample Bead Maker
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- 0.172 mM LiBr wetting agent (0.15 mg ultrapure LiBr in 10 mL DI water)
- 400mg of drew sighed lithium metabolite flux (weighed on shore)
- 10% nitric acid (143 mL concentrated nitric acid/L of solution). Caution! always add acid to water.
- Isopropyl alcohol, laboratory grade
- Methanol, laboratory grade
- Acetone, laboratory grade
- DI water (18.2 M¿ laboratory water obtained from Chemistry Lab)
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To cut samples for the X-Press, use the splitting room rock saws (located in the Core Deck) following these guidelines:
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Polishing the samples remove contamination caused caused by drill bit, saw blade, or other unwanted material. Grind each surface (each outer side) on a high-speed, diamond disc.
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Note: The diamond disc is attached to a magnetic disc which is then placed on the wheel plate. Diamond disks are located on the stud shelf in ICP prep. Use the silver or purple diamond disk.
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Note: The ICP oven should be kept clean at all times, as samples are left open and are susceptible to contamination. The ICP oven should only be used for ICP samples. If the oven shows any sign of rusting, please notify the ALO as a new oven will need to be ordered.
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