8.4.7 Peroxide-Forming Chemical (PFC) Disposal Requirements

Many common organic laboratory solvents, such as ethers or tetrahydrofuran, can form peroxides if not stored appropriately. Detailed storage and testing procedures can be found on the Peroxide-Forming Chemicals Guidance Document.

You are not required to test for peroxides if you are not comfortable doing so, simply state in your disposal request that the solvent has not been tested and note the approximate age of the bottle. The testing and disposal requirements for PFCs depend on the class designation (Class A-D), which are based on the time it takes to form explosive levels of peroxides. Below is a description of the classes along with testing and disposal requirements.

Class A: Chemicals that form explosive levels of peroxides without concentration, even when unopened.

  • Test for peroxides before high-hazard procedures
  • Dispose of within 3 months of receipt

Example: Isopropyl ether, Tetrahydrofuran without inhibitor

Class B: Chemicals that are a peroxide hazard when concentrated through evaporation or distillation.

  • Test for peroxides before high-hazard procedures and every 6 months after opening
  • Dispose of by their expiration date or within 2 years of receipt

Example: Tetrahydrofuran with inhibitor, vinyl ethers, and secondary alcohols

Class C: Chemicals that may autopolymerize without an inhibitor.

  • Test for peroxides before high-hazard procedures and every 6 months after opening
  • Dispose of by their expiration date or within 2 years of receipt

Example: Acrylic Acid, Methyl methacrylate

Class D: Additional chemicals that may form peroxides.

  • Best practice to test before high-hazard procedures or within 2 years of receipt
  • Dispose of by the expiration date or within 2 years of receipt unless the chemical quality is confirmed

Use the chart below to determine appropriate action based on peroxide test results:

Peroxide Concentration

Instruction

Under 20 ppm The solvent is safe for use
Between 20 and 100 ppm The solvent should not be distilled or concentrated
Between 100 ppm and 400 ppm The solvent must be disposed of as waste
Above 400 ppm Immediate HSRM assistance and evaluation is needed

All PFCs with peroxide concentrations > 100 ppm must be disposed of using the online Chemical Waste Disposal Procedures.

  • Indicate the peroxide concentration in the comments section of the online request
  • Do not mix peroxide containing solvents with other waste streams
  • Add a dash of additional inhibitor prior to disposal, if you have it

PFCs with peroxide concentrations > 400 ppm must be evaluated by HSRM to determine the safest method for disposal. Do not move the container and contact HSRM Regulated Waste Program at (612) 626-1604.

Contact the Regulated Waste Program Immediately

  • If crystals are visible on or in the container or lid
  • If the container has a metal screw cap or glass stopper
  • If a Class A compound is past its expiration date 
  • If a Class B or Class C compound has been open for more than 1 year and has not been tested

Do NOT open or move the container. Contact the Regulated Waste Program at (612) 626-1604 for assistance.

For more information and resources, see Chapter 7.5 Peroxide-Forming Chemicals and Highly Reactive Substances.

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