Some chemicals can form peroxides under normal storage conditions. Some of the peroxide chemicals
are unstable, especially when dried or concentrated, and can explode violently when subjected to heat,
light or mechanical shock. In addition, some of the inadvertently formed peroxides can initiate other
unexpected violent reactions (e.g. polymerizations) with other chemicals.
When possible and practical for your work, purchase chemicals that have inhibitors added by the
manufacturer. Label peroxide-forming chemicals with date received and date opened.
Store peroxide-formers in airtight opaque containers with screw caps. Consider oxygen exclusion
methods such as purging with inert gas or sealing containers with parafilm.
Inspect containers for signs of peroxide formation. Do not open a container which has crystals or a
visible cloudiness. Call EHS to come remove it. The friction caused by opening a lid can cause an
Liquids can be tested for presence of peroxide. This is especially important prior to distilation. Most
explosions of peroxide forming chemicals occur when a material is distilled to dryness. Peroxide test kits
are available from chemical vendors. Contact EHS for additional guidance.
Classification Table for Peroxide-Forming Chemicals
Class I:: Unsaturated materials, especially those of low molecular weight, may polymerize violently and
hazardously due to peroxide initiation. These chemicals can spontaneously decompose, becoming
explosive after exposure to air with concentration. Discard unopened containers within 3
months. Opened containers should be tested for peroxides every 2 months.
Class II: The following chemicals are a peroxide hazard upon concentration (distillation/evaporation). A
test for peroxide should be performed if concentration is intended or suspected. Discard unopened
containers within 6 months. Opened containers should be tested for peroxides every 2 months.
Diethylene glycol dimethyl ether
Isopropyl propyl ether
Isopropyl vinyl ether
Allyl ethyl ether
Allyl phenyl ether
Allyl vinyl ether
Benzyl butyl ether
Benzyl ethyl ether
2-Methoxyethyl vinyl ether
Butyl ethyl ether
Butyl vinyl ether
Methyl vinyl ether
2-Chloroethyl vinyl ether 1,2-Epoxy-3-isopropoxy propane
Ethyl isopropyl ether
Ethyl propenyl ether
Ethyl vinyl ether
Cyclopropyl methyl ether 2-Ethylacryladehyde oxime
Ethylene glycol dimethyl ether
2-Ethylhexyl vinyl ether
Isobutyl vinyl ether
Class III: Peroxides derived from the following compounds may explode without concentration.
Sodium amide (sodamide)
NOTE: Lists are illustrative but not exhaustive.
From Prudent Practices in the Laboratory, National Academy Press, 1995 and other sources.