Organic and inorganic peroxides are widely used in research labs due to their exceptional reactivity. However, because of their exceptional reactivity, peroxide formers are some of the most dangerous items we have on site and some of the most expensive to prepare for transport to a disposal facility. This cost increases significantly (goes from a few hundred dollars to more than $10,000) if they are older than 12 months, past their expiration date, and/or have no documentation showing that they have been tested for peroxides in the last 6 months.
What is a peroxide former?
A peroxide former is a chemical that can react with atmospheric oxygen to create shock-sensitive, explosive peroxide crystals. These chemicals are often organic compounds with weak carbon-hydrogen bonds, such as ethers and certain alcohols, and their danger increases when they are distilled, evaporated, or left exposed to air and light for extended periods. Proper storage, labeling, and periodic testing are crucial to prevent explosions.
How peroxide formers become hazardous?
- Oxidation: When exposed to oxygen, these chemicals undergo a chain reaction that forms peroxides.
- Concentration: The hazard becomes critical when the chemicals are concentrated, such as during distillation or evaporation, as this leads to a higher concentration of peroxides.
- Degradation: Over time, even without concentration, some chemicals can form explosive levels of peroxides.
Examples of peroxide formers
- Ethers: Diethyl ether, tetrahydrofuran (THF), and dioxanes are common examples
- Alcohols: Primary and secondary alcohols, especially those used for distillation, are at risk
- Other compounds: Aldehydes, alkenes, and compounds containing allylic or benzylic hydrogens are also considered peroxide formers.
Safety precautions
- Quantity: Purchase peroxide-forming chemicals in small quantities. Avoid prolonged storage. Some peroxide formers must be disposed within 3 or 6 months of opening. No peroxide former should be on site for more than 12 months after opening.
- Labeling: Always label containers with the date of receipt and date container was opened. All peroxide forming chemicals turned into UAMS Safety for disposal must have dates corresponding to when the bottle was received and first opened.
- Storage: Store peroxide formers in airtight containers away from light, sources of ignition, and heat. Secure the lids and caps on these containers to inhibit the evaporation and subsequent concentration of these chemicals.
- Testing: Test and document the test performed for peroxides at least every 6 months, especially before distillation or evaporation. Methods to test for peroxides may include using a peroxide former test strip or using the iodine detection method. Without this information peroxide forming chemicals are treated as highly reactive. Highly reactive chemicals significantly increase the cost of disposal for the University.
- Visually Inspect: Visible indicators of peroxide presence include:
- Clear liquid containing suspended wisp-like structures
- Precipitated crystal formation appearing like chips, ice-like forms, or a solid mass
- Appearance of cloudiness
- White crystal formation under the rim of the cap—if you notice crystal formation in the container or around the cap, do not attempt to open or move the container.
- Gross contamination
- Visible discoloration
- Obvious deterioration or deformation of container
- Disposal: Notify UAMS Safety that the item needs to be discarded prior to its expiration date or after a positive peroxide test, even if unopened.
From: UAMS Department of Environmental Health & Safety