Correct storage of chemicals is important to avoid spills and unwanted chemical reactions among incompatible chemicals stored next to each other. Chemicals should be stored in cabinets or on stable shelving.

Containers

Chemicals must be stored in containers made of material that is compatible with the chemical. For example:

• Some chlorinated solvents degrade plastics;
  
• Hydroxide solutions dissolve aluminum and etch glass;
• Hydrofluoric acid dissolves glass.

Containers must be in good condition (no signs of cracks or corrosion) and must have lids that can be closed tightly to prevent evaporation and leakage even if the container falls over.

Cabinets

Chemical storage cabinets should be made of chemically resistant material and labeled accordingly, e.g.,

“Acid–Corrosive”
“Base–Corrosive”
“Flammable–Keep Fire Away”

Ventilation is recommended for corrosives, volatile poisons, or malodorous chemicals. For more information on storage and use of flammable liquids in laboratories, refer to the DRS guide on Flammable Liquids .

Shelving

Shelving must be sturdy and secure. Do not use shelving with questionable stability. Do not store chemicals on shelves higher than six feet. 
Storage of hazardous chemicals on the bench top is discouraged.

Storage under sinks is limited to non-hazardous chemicals and compatible chemical classes found in average household items such as sodium bicarbonate and bleach.

Chemical Segregation Guidelines

Incompatible chemical classes must be segregated by cabinets, distance, and/or secondary containment. Review the manufacturer’s Safety Data Sheet to identify incompatibilities. For chemicals that fall under multiple hazard categories, store according to priority of hazard level, with flammability and toxicity as the most severe hazards. 

• Store flammables, acids, and bases in designated cabinets.
• Separate acids from bases, cyanides, azides, bleach, sulfides, metals. Keep acids away from acid-sensitive chemicals that can create toxic gases, heat, fire, or pressure.
• Separate oxidizing acids (chromic, nitric, perchloric, perbromic, periodic, and sulfuric acids) from organic acids.
• Separate oxidizers from organics and reducing agents. Oxidizers are recognized by a pictogram on the container showing a ring on fire or by a yellow band (containers from Fisher). Be careful not to miss the following common organic oxidizers: PCC (C₅H₅NHClCrO₃) and mCPBA (C₇H₅ClO₃).
• Store organics and inorganics separately. Store organics in ascending order according to the number of carbons. Inorganics may be stored alphabetically or by metal.
• Separate pyrophoric materials from flammables.
• Separate corrosives from gas cylinders, lecture bottles, and equipment. Corrosives can cause serious damage to expensive and sensitive equipment. 
• Separate water reactives from water sources. Water-reactive chemicals (e.g., thionyl chloride, POCl3, sodium hydride) should be stored away from water sources such as rotovap baths, sinks, eyewash stations, and emergency showers.

For more information on chemical compatibility see the guidance document Chemical Compatibility.

Desiccators

Use desiccators for chemicals that react with air or water or are hydroscopic. Make sure that separate desiccators are used for incompatible chemicals. Store chemicals that are air-sensitive in desiccators that can be evacuated and backfilled with an inert gas.

Dry box desiccators with drierite

Desiccator with vacuum capability

Refrigerator/Freezer Storage

Chemical storage refrigerators must be clearly labeled “No Food or Drink.” Flammable-material storage refrigerators are mandatory for the storage of flammable chemicals. Use only refrigerators that have been approved by Underwriters Laboratory (UL) or Factory Mutual (FM). Freezer ice buildup must be corrected immediately to maintain unobstructed access to chemicals, upright storage of bottles, and to ensure that the unit is functioning properly.

Maintenance

Regularly check all chemical storage areas for leaking containers, old chemicals, and unneeded chemicals. Some chemicals become more hazardous as they age. Old bottles whose contents have likely degraded should be disposed of. This will save storage space and remove unnecessary hazards from the lab.

References

NRC (National Research Council). Prudent Practices in the Laboratory. Handling and Management of Chemical Hazards. National Academy Press: Washington, DC, 2011.

Pitt, M. J. In Bretherick’s Handbook of Reactive Chemical Hazards 6th ed.; Urben, P. G. Ed.; Butterworth-Heinemann Ltd: Oxford, 1999; Vol. 2, pp 307-312.