Peroxide-Forming Compounds Guidelines
A. Peroxide-Forming Compounds
The formation of peroxides in solvents or reagents has caused many laboratory accidents. Ethers are
perhaps the most well-known class of peroxide formers; however, there are many other compounds
that are known to produce dangerous levels of peroxides. Common classes of compounds that form
peroxides include:
i/ Ethers, acetals, and ketals, especially cyclic ethers and those with primary and/or secondary
alkyl groups.
ii/ Aldehydes, including acetaldehyde and benzaldehyde.
iii/ Compounds containing benzylic hydrogens.
iv/ Compounds containing allylic hydrogens, including most alkenes; vinyl and vinylidene
compounds, and dienes.
A peroxide is any compound containing an O-O bond. Since these compounds can readily release
oxygen, they are considered to be strong oxidizing agents and fire hazards. They are sensitive to shock,
sparks and flames. The danger is increased when peroxide forming chemicals are concentrated by
distillation or evaporation.
It is important to manage all peroxide-forming compounds according to the directions provided below
to prevent serious accidents. Peroxide inhibitors are included in most compounds, but may not be
sufficient once the container is opened. Peroxide-forming compounds must be dated upon opening and
tested for peroxide formation every 3 or 12 months. Please refer to the list of the more commonly used
peroxide-forming compounds and testing requirements provided in Appendix A.1
B. Use and Storage of Peroxide-Forming Compounds
i/ Store peroxide-forming compounds in a sealed bottle, in a cool and dark place.
ii/ Label all peroxide-forming compounds.
iii/ Purchase chemicals in the smallest amount possible.
iv/ Keep a detailed inventory of all peroxide-forming compounds
v/ Do not open a container that is more than 2 years old and was not tested according to the
schedule.
vi/ Test for peroxides regularly.
vii/ Distillation of peroxide-forming compounds without first removing peroxides is an especially
dangerous explosion hazard.
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C. Labels for Peroxide Forming Compounds
Labels for peroxide-forming compounds are available at Science Stores and on the EHS webpage at
http://www.sfu.ca/srs/ehs.html. Science Stores will put labels on peroxide-formers kept in stock.
D. Testing for Peroxides
1. Initial Screening
Examine the container for visible discoloration or crystals. If none are observed, it is safe to test
for peroxides. If discoloration or crystals are observed, isolate the bottle and inform lab
occupants. Immediately contact EHS to arrange for special disposal of the chemical.
2. Test for peroxides
 Test Strip Method: Peroxide test strips detect inorganic and organic compounds that
contain a peroxide or hyperperoxide group. It can be used as a routine test for simple
ethers such as diethyl ether, tetrahydrofuran and dioxan. The following peroxides either do
not react or do so with considerably reduced sensitivity: tert-butyl perbenzoate, dicumyl
peroxide, di-tert-butyl peroxide and 1,3-cyclooctadiene. Examples of test strips include the
EM Quant Test Strips (Fisher Scientific) and Quantofix Peroxide Test Strips (Sigma-Aldrich).
Test strips are available (free of charge) at Science Stores. Follow the directions provided
by the supplier.
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 Iodide Test Method: This method is suitable for testing any peroxide-forming compound.
i/ Wear chemical resistant gloves, a lab coat and eye protection. Work in a fume hood.
ii/ Dissolve 100 mg of potassium iodide in 1 mL of glacial acetic acid.
iii/ Add the mixture to 1 mL of the chemical being tested. Use a 10 mL graduated cylinder.
iv/ Determine the colour of the resulting mixture. A pale yellow colour indicates a
peroxide concentration of 10 – 50 ppm. A bright yellow or brown colour indicates a
peroxide concentration of 100 ppm or greater.
E. Peroxide Removal Procedures
Peroxides can be removed from a solvent by passing it through a column of basic activated alumina,
by treating it with indicating molecular sieves, or by reduction with ferrous sulfate. Although these
procedures remove hydro peroxides, which are the principal hazardous contaminants of peroxideforming solvents, they do not remove dialkyl peroxides, which are usually present in small quantities.
Detailed explanations of each procedure are provided in Appendix B.
F. Disposal of Chemicals that Test Positive for Peroxides
If peroxides are detected in concentrations of 10-30 ppm, peroxides should be stabilized and/or
removed. After stabilization, chemicals may be disposed of by the regular chemical waste pick-up
procedure. If peroxides are detected in concentrations greater than 30 ppm, the material is
considered potentially explosive. Isolate the bottle and advise lab occupants not to handle or
otherwise disturb it. Contact EHS immediately to arrange for special disposal of the chemical.
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APPENDIX A
Test Every 3 Months
Test the following compounds for peroxides every 3 months, after opening, and before use. They can form
explosive peroxides during storage.
divinyl acetylene
divinyl ether
potassium metal
vinylidene chloride
chloroprene
● isopropyl ether
● potassium amide
● sodium amide
● butadiene
Test Every 12 Months
Test the following compounds for peroxides every 12 months, after opening, and before use. They can
form explosive peroxides during concentration.
acetal
acetylaldehyde
benzyl alcohol
2-butanol
Cumene
Cyclohexanol
cyclohexene
decahydronaphthalene
diacetylene
dicyclopentadiene
diethylene glycol dimethyl ether
diethyl ether
dioxanes
dimethyl ether
ethylene glycol dimethyl ether (glyme)
● 4-Heptanol
● 2-hexanol
● methyl acetylene
● 3-methyl 1-butanol
● methylcyclopentane
● methyl isobutyl ketone
● 2-pentanol
● 4-penten-1-ol
● 1-phenylethanol
● 2-phenylethanol
● 2-propanol
● tetrahydrofuran
● tetrahydronaphthalene
● vinyl ethers
Test Every 12 Months
Test these compounds every 12 months also. They can initiate explosive conditions once peroxides are
formed.
acrylic acid
acrylonitrile
butadiene
chloroprene
chlorotrifluoroethylene
methyl methacrylate
styrene
● tetrafluoroethylene
● vinyl acetate
● vinyl acetylene
● vinyl chloride
● vinyladiene chloride
● vinyl pyridine
1
Please note these lists are not exhaustive. Check the Material Safety Data Sheet (MSDS) of all chemicals to
determine if they form peroxides and for additional safe handling procedures.
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APPENDIX B
Peroxide Removal Procedures
A. Basic Activated Alumina
A 2.0 cm x 3.0 cm column filled with 80.0 grams of 80-mesh F-20 Alcoa or Woelm basic
activated alumina is usually sufficient to remove all peroxides from 100-400 mL of common
peroxidizable liquids. After passage through the column, the solvent should be re-tested to
confirm that the peroxides have been removed. The wet alumina should be slurried with a
dilute acidic solution of ferrous sulfate or potassium iodide before being discarded.
B. Molecular Sieves
This method for removing peroxides from ethers involves refluxing 100.0 mL of the ether with
5.0 grams of 4-8 mesh, indicating activated 4A molecular sieve pellets for several hours under
nitrogen. The sieve pellets that are separated from the ether present no potential hazard
because hydro peroxides are destroyed during the operation.
C. Ferrous Sulfate
Peroxides in 100.0 mL of water-insoluble solvent can usually be removed by shaking with 80.0
mL of acidified ferrous sulfate solution (6.0 grams of FeSO4•7H20 / 0.60 mL conc. H2SO4 /
11.0 mL H20) in a separatory funnel or stirred vigorously in a flask until the solvent no longer
gives a positive test for peroxide; often a few minutes will suffice.
Most dialkyl peroxides (ROOR) do not react readily at room temperature with ferrous sulfate,
iodide ions, ammonia, or other reagents mentioned above. However, these peroxides can be
destroyed by a modification of the iodine procedure.
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