Neutralization and Disposal of Osmium Tetroxide

A 2% solution of Osmium Tetroxide can be fully neutralized by twice the volume of oil.  Peanut oil can be used but corn oil is preferred because of its high percentage of unsaturated bonds.  Therefore, for every 10 ml. of 2% Osmium Solution, 20 ml.s of corn oil is required.  Here is the procedure from Electron Microscopy Sciences of Hatfield PA:

1. Do all work under a fume hood

2. Pour twice the volume of corn oil into used osmium tetroxide solution

3. Wait 3 to 5 minutes for the solution to turn completely black

4. Dip a piece of filter paper for 2 to 3 seconds into fresh corn oil

5. Place the filter paper over the osmium tetroxide solution

6. If the filter paper begins to turn black it indicates that osmium tetroxide is still present.  Add additional corn oil (approximately half of the initial volume of the solution) and wait another 3 to 5 minutes

7. Repeat steps 4 through 6 until the filter paper no longer turns black

8. Dispose of the solution in accordance to your local regulations.