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Environmental Health & Safety


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Peroxidizable Compounds

Organic peroxides are considered low-power explosives that are sensitive to shock, sparks, and other accidental ignition.  Several compounds that may be found in labs present a similar hazard because they can undergo auto-oxidization to form organic hydroperoxides and/or peroxides when exposed to oxygen in air.  Ultraviolet light may cause a free-radical chain mechanism.  Oxygen may be added resulting in the formation of the peroxy radical.

Actions can be taken to reduce the formation of peroxides.  Storing the chemical under inert atmosphere (N2 or argon) or under vacuum can increase the safe storage lifetime.  Also, chemical manufacturers add stabilizers or inhibitors to inhibit peroxide formation.

Prudent Practices in the Laboratory, Handling and Management of Chemical Hazards, 2011 edition, provides useful test methods to determine if peroxide formation has occurred.  Routine testing should be done prior to the expiration date on the container.  The following three tests methods can be used to check for peroxy and hydroperoxide formation:

  • Peroxide test strips:  These turn to an indicative color in the presence of peroxides.  NOTE:  When used, the strip must be air dried until the solvent evaporates and exposed to moisture for proper indication and quantitation.
  • Add 1 to 3 ml of the liquid to be tested to an equal volume of acetic acid, add a few drops of 5% aqueous potassium iodide solution, and shake.  The appearance of a yellow to brown color indicates the presence of peroxides.  Alternately, addition of 1 ml of a freshly prepared 10% solution of potassium iodide to 10 ml of the organic liquid in a 25 ml glass cylinder produces a yellow color of peroxide is present.
  • Add 0.5 ml of the liquid to be tested to a mixture of 1 ml of 10% aqueous potassium iodide solution and 0.5 ml of dilute hydrochloric acid to which has been added a few drops of starch solution just prior to the test.  The appearance of a blue or blue-black color within 1 minute indicated the presence of peroxides.

Class A: Chemicals posing peroxide hazard without concentration

  Butadiene   Isopropyl ether   Tetrafluoroethlene
  Chlorobutadiene   (chloroprene)   Potassium amide   Vinylidene chloride
  Divinyl acetylene   Potassium metal  
  Divinyl ether   Sodium amide (sodamide)  

If a container of a Class A peroxidable is past its expiration date, or if the presence of peroxides is suspected or proven, DO NOT ATTEMPT TO OPEN THE CONTAINER!

Class B: Chemicals posing peroxide hazard upon concentration (distillation or evaporation)

  Acetal   Dicyclopentadiene   Methyl acetylene
  Cumene   Diethylene glycol dimethyl ether (diglyme)   Methyl cyclopentane
  Cyclohexene   Diethyl ether   Methyl isobutyl ketone
  Cyclooctene   Dioxane (p-dioxane)   Tetrahydrofuran
  Cyclopentene   Ethylene glycol dimethyl ether (glyme)   Tetrahydronaphtalene
  Diacetylene   Furan   Vinyl ethers

A test for peroxide should be performed.

Class C: Unsaturated materials that may autopolymerize as a result of peroxide accumulation if inhibitors have been removed or are depleted.

  Acrylic acid   Ethyl acrylate   Vinyl acetylene
  Acrylonitrile   Methyl methacrylate   Vinyl chloride
  Butadiene   Styrene   Vinyl pyridine
  Chlorotrifluoroethylene   Vinyl acetate  

NOTE:  These lists are illustrative but are not exhaustive

QUESTIONS or COMMENTS? Contact EH&S at (585) 275-3241 or e-mail EH&S Questions.

This page last updated 7/30/2015. Disclaimer.