Summary: Acid Washed Glass Beads
1. Weigh 50 g of 0.5 mm glass beads (Sigma G-9268, 425-600 µm) into a 100 ml-orange cap Pyrex
bottle. The volume of glass beads should be no more than 1/5 of the volume of the bottle used for
washes. To scale up, use 100 g of glass beads and a 250 ml orange cap Pyrex bottle.
2. Add 5.8 M HCl to cover glass beads. Alternatively, use concentrated nitric acid.
To prepare 5.8 M HCl, add 1 volume of concentrated HCl to 1 volume of dH2O with moderate
stirring. Be careful! HCl is fuming! Dilute in a fume hood if necessary.
3. Incubate at room temperature for 1 hour.
4. Carefully pour 5.8 M HCl down drain. Some HCl will remain with beads. Rinse HCl down drain
with tap water.
5. Add dH2O to the 80 ml mark on the 100 ml bottle. Swirl bottle for 10 seconds to stir up beads.
The dH2O wash volume should be at least 5X the volume of the beads in the bottle.
6. Pour off the dH2O wash in sink. Rinse wash volume down the drain with tap water.
7. Repeat steps 5 and 6 for a total of 10 washes to reduce the HCl concentration below 10 mM.
8. Autoclave beads for 20 minutes.
9. Dry beads in oven at 50°C overnight.
10. Store beads at room temperature. Spoon out beads with sterile "dipper" made with tip cut from
1.5 ml tube glued to end of plastic transfer pipette. Use gloves that have been washed and dried.