The University of Iowa

Chemical Storage Information

This guide presents one compatible chemical storage method.  There are several appropriate chemical storage group methods available. They are each slightly different but have many overlapping similarities. Proper chemical storage controls health or physical hazards posed by chemical compounds during storage in the lab. It is designed to 1) protect flammables from ignition; 2) minimize the potential of exposure to poisons; and 3) segregate incompatible compounds to prevent their accidental mixing (via spills, residues, earthquakes, fires or human error). These guidelines include Part I - General rules of safe storage, Part II - Definition of storage groups and Part III - Illustrations of storage plans in lab facilities. These guidelines were taken in part with permission and appreciation, from the Fred Hutchinson Cancer Research Center "Hazard Awareness and Management Manual" 

Questions about this topic can be directed here

  • Designate a storage place for each compound.
  • Each stock container of a chemical compound should be returned to its designated location after each use. Storage locations can be marked on containers.
  • Do not store chemicals on the bench top. Only chemicals in use should be on benchtops.
  • Do not store chemicals in the fume hood They may interfere with air flow in the hood or may provide fuel if there is a fire.
  • Do not store chemicals in alphabetical order except within "Chemical Storage Groups". Alphabetical arrangement of randomly collected chemicals often increases the likelihood of dangerous reactions by bringing incompatible materials into close proximity. 
  • Store chemicals away from sun and heat. Storage areas should not be exposed to extremes of heat or sunlight. 
  • Do not store chemicals, except bleach and compatible cleaning agents, under the sink.
  • All containers within the lab must be labeled. 
  • Suspect and known carcinogens must be labeled as such and segregated within trays to contain leaks and spills.
  • This plan does not require security measures (i.e., locked cabinets) to prevent theft, but lab workers should make sure that lab doors are locked when unattended. 
    • Use of chemicals regulated by Drug Enforcement Agency require registration and secured controlled storage. 

Flammable liquids

  • All containers of flammable liquids (flashpoint <140F) should be returned to the flammable cabinet or explosion-safe/proof refrigerator/freezer immediately after use.
  • Do not store flammable in cold rooms which are neither vented nor explosion-proof.

Peroxide formers

  • Peroxide formers must be stored in the flammable cabinets and must be regularly inventoried to track their age. See Peroxide Formers.


  • Store volatile poisons (evaporation rate above 1.0; e.g. ether=1.0) in a flammable cabinet.
  • Store non-volatile liquid poisons in a refrigerator or cabinet. Amounts less than 1 liter may be stored in a cabinet above bench level if the cabinet has sliding doors.

Acids and bases

  • Acids and bases should be physically separated.
  • All acids should be stored in a corrosive cabinet. Oxidizing acids (nitric, phosphoric, perchloric, chromic acid, etc.) should have secondary containment and, as a group, stored separately from other acids (organic and mineral).

In this plan there are nine storage groups. Seven of these groups cover storage of liquids because of the wide variety of hazards posed by these chemicals. Specific instructions must be followed for metal hydrides (Group VIII) and certain individual compounds, but otherwise, dry solids are in Group IX. 

PLEASE NOTE: Many liquid chemicals pose hazards that correspond to more than one storage group. These chemicals should be stored in the lowest group number and within secondary containment (tray, tub, etc.).

  • Group I Flammable Liquids 
  • Group II Poisons - volatile
  • Group III Acids - Oxidizing
  • Group IV Acids - Organic and Mineral
  • Group V Bases - Liquid
  • Group VI Oxidizer - Liquid
  • Group VII Poisons - Non-volatile
  • Group VIII Reactives
  • Group IX Solids

Group I: Flammable Liquids

Includes liquids with flashpoints < 100° F. 

Examples: alcohols, acetone, acetaldehyde, acetonitrile, amyl acetate, benzene, cyclohexane, dimethyldichlorosilane, dioxane, ether, ethyl acetate, glacial acetic acid, hexane, hydrazine, methyl butane, picolene, piperidine, propanol, pyridine, scintillation liquids, all silanes, tetrahydrofuran, toluene, triethylamine, and xylene. 

Primary Storage Concern: To protect from ignition. 

Recommended Facilities/Measures:

  1. Flammable Cabinet
  2. Flammable- or explosion-proof refrigerator

Compatible Storage Groups: Volatile poisons may be in the same compartment of the flammable cabinet as flammables if bases are not present.

Group II: Volatile Poisons

Includes poisons, toxics, and known or suspected carcinogens with an evaporation rate greater than 1 (butyl acetate = 1). 

Examples: carbon tetrachloride, chloroform, dimethylformamide, dimethyl sulfate, formamide, formaldehyde, halothane, mercaptoethanol, methylene chloride, phenol. 

Primary Storage Concern: To prevent inhalation exposures.

Recommended Facilities/Measures:

  1. Flammable Cabinet
  2. Flammable- or explosion-proof refrigerator

Compatible Storage Groups: Volatile poisons may be in the same compartment of the flammable cabinet as flammable if bases are not present. 

Group III: Oxidizing Acids

An oxidizing acid is a Brønsted acid that is a strong oxidizing agent. An oxidizing agent (oxidant, oxidizer) is a substance that has the ability to oxidize other substances — in other words to cause them to lose electrons. All oxidizing acids are highly reactive with most substances and each other. 

Examples: nitric, sulfuric, perchloric, phosphoric acids, and chromic acids. 

Primary Storage Concern: Preventing contact and reaction with each other and other substances and corrosive action on surfaces. 

Recommended Facilities/Measures:

  1. Corrosive Cabinet.
  2. Each oxidizing acid must be double-contained, i.e., the primary container must be kept inside canister, tray or tub. 

Compatible Storage Groups: Oxidizing acids must be double-contained and should be segregated in their own compartment in a corrosive cabinet. Small quantities may be double-contained and stored with Group 4 Organic and Mineral Acids. Store oxidizing acids on bottom shelf below Group 4. 

Group IV: Organic and Mineral Acids

A material (usually in a solution) that dissolves metals and other materials. A material that produces positive ions in solution. An acid is the opposite of a base and has a pH < 7.

Examples: acetic, butyric, formic, hydrochloric, isobutyric, mercaptoproprionic, proprionic, trifluoroacetic acids. 

Primary Storage Concern: To prevent contact and reaction with bases and oxidizing acids and corrosive action on surfaces.

Recommended Facilities/Measures:  

  1. Corrosive cabinet. 

Compatible Storage Groups: Small amounts of double-contained oxidizing acids can be stored in the same compartment with organic acids if the oxidizing acids are stored on the bottom shelf. 

Exceptions: acetic anhydride and trichloroacetic anhydride are corrosive. These acids are very reactive with other acids and should not be stored in this group. It is better to store these with organic compounds as in Group 7 Non-volatile Liquid Poisons. 

Group V: Liquid Bases

A base is a material that produces hydroxide (OH¬¬-) in solution. A base is the opposite of an acid and has a pH > 7.

Examples: sodium hydroxide, ammonium hydroxide, calcium hydroxide, and glutaraldehyde. 

Primary Storage Concern: Preventing contact and reaction with acids.

Recommended Facilities/Measures:

  1. Corrosive cabinet
  2. In tubs or trays in normal cabinet. 

Compatible Storage Groups: Liquid bases may be stored with flammables in the flammable cabinet if volatile poisons are not also stored there.

Group VI: Oxidizing Liquids

An oxidizing agent (oxidant, oxidizer) is a substance that has the ability to oxidize other substances — in other words to cause them to lose electrons. Oxidizing liquids react with everything potentially causing explosions or corrosion of surfaces. 

Examples: ammonium persulfate, hydrogen peroxide (if greater than or equal to 30%). 

Primary Storage Concern: To isolate from other materials. 

Recommended Facilities/Measures:

  1.  Total quantities exceeding 3 liters should be kept in a cabinet housing no other chemicals.
  2.  Smaller quantities must be double-contained if kept near other chemicals, e.g., in a refrigerator. 

Compatible Storage Groups: None

Group VII: Non-Volatile Liquid Poisons

Includes highly toxic (LD50 oral rat < 50 mg/kg) and toxic chemicals (LD50 oral rat < 500 mg/kg), known carcinogens, suspected carcinogens and mutagens. 

Examples: acrylamide solutions; diethylpyrocarbonate, diisopropyl fluorophosphate, uncured epoxy resins, ethidium bromide and triethanolamine.

Primary Storage Concern: To prevent contact and reaction with other substances.

Recommended Facilities/Measures:

  1. Cabinet or refrigerator (i.e., must be enclosed)
  2. Do not store on open shelves in the lab or cold room.
  3. Liquid poisons in containers larger than 1 liter must be stored below bench level on shelves closest to the floor. 
  4. Smaller container of liquid poison can be stored above bench level only if behind sliding doors.

Compatible Storage Groups: Non-hazardous liquids (e.g., buffer solutions).

Group VIII: Reactives Metal Hydrides and Pyrophorics

Most metal hydrides react violently with water, some ignite spontaneously in air (pyrophoric).

Examples: sodium borohydride, calcium hydride, lithium aluminum hydride, boron, diborane, dichloroborane, 2-Furaldehyde, diethyl aluminum chloride, lithium, white or yellow phosphorus and trimethyl aluminum. Other water reactives include aluminum chloride-anhydrous, calcium carbide, acetyl chloride, chlorosulonic acid, sodium, potassium, phosphorous pentachloride calcium, aluminum tribromide, calcium oxide, and acid anhydrides.

Primary Storage Concern: To prevent contact and reaction with liquids and, in some cases, air. 

Recommended Facilities/Measures:

  1. Secure, water-proof double-containment according to label instructions.
  2. Isolation from other storage groups. 

Compatible Storage Groups: If securely double-contained to prevent contact with water and/or air, metal hydrides may be stored in the same area as Group 9 Dry Solids.

Group IX: Dry Solids

Includes all powders, hazardous and non-hazardous. 

Examples: benzidine, cyanogen bromide, ethylmaleimide, oxalic acid, potassium cyanide, and sodium cyanide.

Primary Storage Concern: To prevent contact and potential reaction with liquids. 

Recommended Facilities/Measures: 

  • Cabinets are recommended, but if not available, open shelves are acceptable. 
  • Store above liquids. 
  • Warning labels on highly toxic powders should be inspected and highlighted or amended if they do not cause the containers to stand out against less toxic substances in this group.
  • It is recommended that the most hazardous substances in this group be segregated. 
  • It is particularly important to keep liquid poisons below cyanide-or sulfide-containing poisons (solids).
  • A spill of aqueous liquid onto cyanide - or sulfide - containing poisons would cause a reaction that would release poisonous gas.

Compatible Storage Groups: Metal hydrides, if properly double-contained may be stored in the same area.

Exceptions: Solid picric or picricsulfonic acid can be stored with this group, but should be checked regularly for dryness. When completely dry, picric acid is explosive and may detonate upon shock or friction. Picric acid in contact with some metals may form explosive metal picrates. Use non-metal caps. 

On the following pages are illustrations of possible chemical storage arrangements for two types of lab facilities. They are provided merely as examples of arrangements which satisfy the recommendations of the chemical storage plan. They are not intended to restrict storage designers to the particular arrangements and facilities depicted.

Variation 1: Chemical storage plan for lab with minimal facilities and chemicals in all 9 storage groups.

 Variation 2: Chemical storage plan for lab with freestanding acid cabinet.




  • Chemical Storage Safety - W126CM
    • EHS training course is recommend initially and annually for the indicated audience.
    • Audience: Persons who work with and/or store chemicals in research labs.

For further training and registration information, go to EHS Safety Training.