Which chemicals form peroxides

Some compounds form explosive peroxides. Others are polymerizable unsaturated compounds that can participate a runaway, explosive polymerization reaction catalyzed by peroxides.

To varying degrees, shock, heat, or friction may cause unexpected explosion of peroxidized organic chemicals. Refer to the Appendix for a list of common peroxide forming chemicals and recommendations on safe storage durations. Prior to using peroxide formers and as needed see Appendix , conduct the two-part evaluation for peroxide content:. Peroxide Testing Peroxide forming chemicals should be used or disposed of prior to the expiration date.

If extenuating circumstances exist for keeping the chemical, routine testing must be performed. Visually inspect all containers before opening for crystal formation or cloudiness. Test strips are available from the EHS Department Any chemical that tests greater than ppm should be disposed of, please contact EHS for assistance All test results should be recorded directly on the container. Common chemicals are listed below.

Contact EHS for a more extensive list. Determine if the chemical in question poses a risk of forming peroxides. Inventory all chemical storage at least twice a year. Many methods can be used to stabilize or inhibit the peroxidation of susceptible chemicals. If it does not interfere with the use of the chemical and if available, peroxide-forming chemicals shall be ordered with inhibitor added and peroxide scavengers inhibitors shall be added in small quantities to items that have been redistilled.

Contact OCRS at if the peroxide scavenger interferes with the use of the susceptible chemical. Older containers of peroxide-forming chemicals, or containers of unknown age or history, must be handled very carefully and should never be opened by researchers. Any peroxide-forming chemical with visible discoloration, crystallization or liquid stratification should be treated as potentially explosive.

Older steel containers that have visible rust may also be extremely dangerous. If any of these conditions are observed on a peroxide-forming chemical container or if the origin and age are unknown, do not attempt to move or open the container.

Contact OCRS at to have the container inspected and if necessary disposed of properly. Eliminate the peroxides with a chemical reducing agent or pass the solvent through activated alumina. Carefully monitor the distillation process to ensure that it does not dry out completely, and then overheat. Distillation can concentrate peroxides, especially if taken to a dry state. Peroxides will be present mainly in the still bottoms.

Small pieces of sodium metal can be added to the distillation vessel to reduce peroxides. Suggested time limits are given for testing of these compounds, However, it must be noted that these shelf life durations are minimum criteria, and we recommend more frequent testing for peroxides.

Indicate the peroxide level in the notes of the WASTe tag. There is a great deal of uncertainty regarding the concentration at which peroxides pose a hazard to researchers.

It is important to note that peroxide concentrations greater than 20 ppm is considered explosive and poses issues with Hazardous waste vendors will not pick up containers with 20 ppm peroxide concentration.

There are several methods that are commonly used to detect peroxides in the laboratory. Peroxide test strips provide a simple and convenient mechanism for detection, they are available from several suppliers.

For volatile organic chemicals the test strip is immersed in the chemical for 1 second, then the tester breathes slowly on the strip for seconds or until the color stabilizes. Test strip color is compared with a colormetric scale provided on the test kit bottle.

Strips that offer a PPM peroxide range are useful for determining if the material is below the control point of PPM. Before the end of the storage date for a particular peroxide forming chemical the person using the chemical should either test and dispose of it or test it monthly for peroxide content.

Materials which are older than the suggested shelf life but have been tested and have no detectable peroxides or peroxide concentrations less than PPM may be retained. However, these materials should be tested at frequent monthly or quarterly intervals and peroxides reduced neutralized prior to any distillation or heating. All chemicals which are to be distilled must be tested prior to distillation regardless of age.

Important note - researchers should never test containers of unknown age or origin. Older containers are far more likely to have concentrated peroxides or peroxide crystallization in the cap threads and therefore can present a serious hazard when opened for testing.

Please read section below on managing older containers. Older containers of peroxidizable chemicals, or containers of unknown age or history, must be handled very carefully and should never be opened by researchers.

Older steel containers that have visible rust may also be extremely dangerous. If any of these conditions are observed on a peroxidizable chemical, or if the origin and age of the container are unknown, do not attempt to move or open the container.