Uranyl Formate Stain Preparation for Negative Staining EM.

Any trash generated during this procedure must be disposed of as a combined hazardous waste in the EM Prep area. The container label should read Radioactive hazard boxes should be checked.

  1. Weigh 37.5 mg of uranyl formate (50 mg for small proteins)
  2. Put it into a very small glass beaker
  3. Cover the uranyl formate with aluminum foil at all times
  4. Boil 5 ml ddH2O in a test tube using Bunsen burner (Fisher Sci 10-310-200)
  5. Pour boiling water into the beaker (10 ml glass beaker)
  6. Mix it with a small stirrer bar for 5-10 minutes
  7. Add 1 µl of 5 M NaOH per exactly 6 mg of uranyl formate to adjust the pH (6.25 µl for 37.5 mg)
  8. Mix another 5-10 minutes
  9. Filter the uranyl formate solution with 0.1 or 0.2 µm fresh, good quality filter, cover with foil.

Uranyl formate (UO2(CHO2)2·H2O) is a fine yellow free-flowing powder Cat#24762 PolySciences


Another protocol can be found at Grigorieff Lab. webpage