Peroxides usually form upon evaporation so they will most likely be formed on the threads under the cap. UTEP Peroxide Policy specifies to date all peroxide forming materials with the date received, opened, and the expected shelf life. Chemicals such as isopropyl ether, divinyl acetylene, sodium amide, and vinylidene chloride should be discarded after three months. Chemicals such as dioxane, diethyl ether, cyclohexane, and tetrahydrofuran should be discarded after one year. Store all peroxide forming materials away from heat, sunlight, and sources of ignition.
All organic peroxides are highly flammable and sunlight accelerates the formation of peroxides.
Secure the lids and caps on these containers to discourage the evaporation and concentration of these chemicals. Never store peroxide forming materials in glass containers with screw cap lids or glass stoppers. Friction and grinding must be avoided. Also, never store these chemicals in a clear glass bottle where they would be exposed to light. A test can be performed to check for the presence of peroxides in ether.