Peroxide Formers

Review information regarding Peroxide-Forming materials in Section 7 of USC’s Chemical Hygiene Plan (CHP). Guidance includes:

  • appropriate training
  • storage
  • testing
  • disposal

The table below lists time limits for storage of peroxide-forming materials.

StatusClass AaClass BClass C
Unopened, unstabilized Open or dispose within six months Shall be opened or disposed by manufacturer’s expiry date; otherwise, within 1 year. N/A
Unopened, stabilized Shall be opened or disposed by manufacturer’s expiry date; otherwise, within 2 years. Dispose within 12 months of purchase, unless the bottle is marked by the manufacturer with an expiry date, in which case it may be followed. These materials shall be stored in the dark within the temperature range specified by the manufacturer, which may require a refrigerator (suitably rated for flammables).   If also within Class A, follow the Class A time limts.
Opened, stabilized Dispose within three months of openingb Dispose or test for peroxides within 12 months of opening, or by manufacturer’s expiry date if sooner.b c d
Opened, unstabilized Stored in air: Dispose or test for peroxides within 6 months of opening.b c If used under conditions where peroxides might be dangerously concentrated (e.g. by evaporation of solvent), additionally test before use and log results.e   Stored under nitrogen: Rubber-septum bottle — Dispose or test for peroxides within 12 months of opening, or by manufacturer’s expiry date if sooner. Glass vessel sealed with reliable valve.dUninhibited Class C materials shall only be produced in small quantities (a few mL) during the course of an experiment and shall not be stored more than 24 h.   Production and use of uninhibited Class C materials shall be covered by an SOP.

a  Organic Class A materials only. For the rules on potassium, potassium alloys, sodium amide, potassium amide, and other alkali metal amides, refer to the section Inorganic “Peroxide-Forming” Materials, above.

b  This incudes materials in a bottle with a rubber septum.

c  After the first peroxide test, testing (recorded in a bottle-specific log of test results) shall continue at 12 or 6 month intervals, as appropriate. A peroxide test is considered to pass if the reading is <100 ppm.

d  When de-aerated and stored under N2 in a glass vessel sealed with a reliable valve (e.g., CHEM-VAC™ CHEM-CAP® valves or a similar type):

  1. The date of filling shall be recorded.
  2. The contents shall be disposed or tested for peroxides if the valves are found to have leaked in storage.
  3. In any event, the contents shall be disposed or tested for peroxides after 3 years.

e  As an example of the hazard posed, unstabilized THF is considered as becoming potentially hazardous for distillation after only 2-3 days storage in air (see page 32 of Kelly, 1996).