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Osmium Tetroxide Waste Disposal

Osmium tetroxide is acutely toxic, a severe irritant to the eyes and respiratory tract, and can cause irreversible eye damage or possible blindness. Osmium tetroxide also causes long-term toxicity to liver and kidneys.

Neutralizing Osmium Tetroxide Before Disposal:

The following neutralization procedure should be used to reduce the hazards involved in osmium tetroxide disposal:

  1. Perform the neutralization procedure in a chemical fume hood and wear appropriate PPE, including gloves, a lab coat, and eye protection.
  2. A 2% solution of osmium tetroxide can be fully neutralized by twice its volume of vegetable oil (corn oil is preferred because of its high percentage of unsaturated bonds). For every 10 mL of 2% osmium tetroxide solution, 20 mL of corn oil is required. Pour the corn oil into the osmium tetroxide solution.
  3. Wait for the oil to completely turn black.
  4. To test if osmium tetroxide is fully neutralized, hold a piece of filter paper soaked in corn oil over the solution. Blackening indicates that osmium tetroxide is still present and more corn oil should be added.
  5. Aqueous solutions contaminated with osmium tetroxide can be fully neutralized by adding sodium sulfide or sodium sulfite to reduce osmium tetroxide to less hazardous forms.
  6. Dispose of the neutralized solutions as hazardous waste.

Osmium Tetroxide Disposal Procedure:

  • Due to the toxicity of osmium tetroxide, empty containers must also be collected and disposed of as hazardous waste.
  • Do not discard any osmium tetroxide down the sink drain.
  • Collect pipette tips, eppendorf tubes, gloves, and other materials contaminated with osmium tetroxide in a sealable container separate from other hazardous chemical waste.
  • Research Safety Affairs prefers the use of puncture-proof, sealable, and disposable containers to store osmium tetroxide waste. Please note that these containers will not be given back to you (they are for one time use), nor does Research Safety Affairs supply these containers. You may purchase these containers from general stores or they can be found through regular lab supply routes.
  • Container must have a hazardous waste label affixed and filled out to identify osmium tetroxide as the hazardous content.
  • Container must remain closed when not actively being filled.
  • Request hazardous waste pickup when container is 90% full by emailing
May 26, 2022