Peroxide Forming Chemicals
A spontaneous free radical reaction may occur between organic compounds and molecular oxygen to form peroxides. This reaction is often facilitated by light. Under normal laboratory conditions this reaction may result in an increasing concentration of peroxides in a chemical container and lead to the formation of potentially explosive peroxide crystals. These crystals may explode when subjected to mechanical shock from merely opening the container. For this reason, it is necessary to observe the following safety regulations:
- All laboratories working with peroxide forming chemicals (PFC) must maintain an inventory control program for PFC to ensure these chemicals are removed from inventory as indicated, examined for signs of potential peroxides, and/or tested for peroxides.
- Order only quantities necessary to complete an experiment and that will be used up within a year unless the chemical is a Class A peroxide forming chemical. See Appendix C: Peroxide Forming Chemicals Management for detailed information.
- Purchase PFCs with added peroxide formation inhibitor, whenever possible.
- PFCs must be appropriately labelled, including the date opened and expiration date as according to manufacturer. Expired chemicals must be promptly disposed of by EHS as hazardous waste.
- Document on label the dates of peroxide testing and additions of inhibitors.
- Store in sealed, air tight, light resistant containers. Leave in original manufacturer containers whenever possible.
- Use oxygen exclusion practices whenever possible (i.e. purge with inert gas).
- Class I and Class III PFCs should be tested for the presence of peroxides prior to use and all PFCs should be tested prior to concentration, i.e. distillation, evaporation, etc. (see below).
- Do not concentrate solutions that may contain peroxides.
- PFCs that have been purified of inhibitors must have inhibitors reintroduced upon storage.
- Peroxide forming chemicals must be visually inspected for increased viscosity, crystal formation, or stratification, and age before use as these signs indicate an elevated explosion risk. It is imperative that containers exhibiting these signs not be opened as the mechanical forces could detonate the crystals.
- Peroxide forming chemicals should be tested before use. Peroxide testing strips are available from chemical manufacturers (example: Quantofix Peroxide Test Strips [Sigma-Aldrich Part # Z249254 and Z101680]). However, there are interferences to this test method.
- Potassium iodide indicators may be used to test for the presence of peroxides.
Due to the hazards posed by poorly managed PFC, EHS requires that departments/PI/Lab Managers maintain appropriate hazard controls on PFC. It is imperative for your safety and the safety of hazardous waste technicians and waste contractors that you provide accurate information about these materials and that you responsibly manage your inventory. When submitting a hazardous waste pick up request for PFC, you may be asked to confirm that you have a PFC management program in place.
Contact EHS (785-532-5856) when you discover a suspect PFC container (presence of crystals, cloudiness, visible precipitate, discoloration, liquid stratification, or oily viscous layer). Do not open the container. Mark the container storage area or shelf with the words “Danger: Peroxide Hazard”. Instruct others not to handle the container.
Containers of unknown age or history should be considered suspect. Do not attempt to open. Submit a waste disposal request and indicate the potential hazard and/or Contact EHS at 785-532-5856.
Due to the high cost of disposal and potential risks of improperly managed PFC, departments or PIs may be charged back for handling and disposal costs for PFC that are not properly dated and managed as described herein.