Chapter 4: Proper Storage of Chemicals in Laboratories
This chapter instructs you how to interpret the labels on chemical containers, and how to safely store chemicals in the laboratory in a way that minimizes incompatible chemical reactions, spillage, breaking, or waste due to expiration.
Examples of chemicals in poor condition, that you should NOT keep stored in your lab:
- Expired/outdated chemicals
- Illegible/removed labels
- Degraded containers
- Leaking lids
The best seal is the screw cap with a conical polyethylene or Teflon insert (Figure 4.2). Seal the caps with tape or Parafilm® “M” as a further precaution. Additional protection can include wrapping the container in an absorbent paper, sealing it inside a plastic bag, and storing the bag inside a metal can with a friction fitting lid.
- Reduced storage hazards
- Reduced storage space
- Safety in handling smaller quantities
- Reduced losses due to out-of-date chemicals
- Minimized cost of disposal of “leftovers”
Frequently, it costs many times more than the original purchase price to dispose of leftover chemicals. Chemical storerooms on campus keep supplies of the most frequently used solvents and chemicals to lessen the need for laboratory stockpiles.
Recognizing the need for a universal method to identify potentially hazardous substances, the United Nations has created a worldwide Globally Harmonized System (GHS) for label elements and safety data sheets. Because of the numerous languages used by the worldwide research community, the GHS relies heavily on picture glyphs to convey the basic information. Below are GHS glyphs that will begin appearing on chemical labels and SDSs. Training on the EHS website outlines the GHS standards. Several premade GHS labels are available on the EHS GHS Labels webpage.
- Fire Hazard and/or Flammables
- Contact Hazard and/or Corrosive (acids or bases)
- Health Hazard and/or Toxic or Poisonous
- Reactivity Hazard and/or Oxidizers
- Green, Gray or Orange
- Moderate or slight hazard (general chemical storage)
- Striped or “Stop”
- Exceptions within the same color code labels (example – yellow label chemicals are stored apart from striped yellow label chemicals)
Cold rooms have closed air circulation systems that re-circulate escaped vapors within the chamber. The refrigeration coils in cold rooms are aluminum and subject to damage from corrosive atmospheres. The electrical systems normally have vapor proof lights and duplex outlets, but added-on extension cords and plug strips compromise these safety features. Cold rooms are not acceptable for storage of flammables, dry ice, highly toxic liquid chemicals, or compressed gases. If you must refrigerate these chemicals, store them in an approved refrigerator or freezer, rather than a cold room. Post a hazard information sign on the cold room door as illustrated (Figure 4.8). This sign is also available from the EHS Safety Labels webpage.
*Note that only 30 gallons (113.6 liters) of Class I liquids are permitted per room. Class I liquids have a flash points less than 100 °F (37.8 °C), and are traditionally known as “flammable” liquids. Most liquids labeled as flammable are Class I liquids. Combustible liquids are Class II or III liquids, and have flashpoints above 100 °F (37.8 °C). Regulations permit up to 60 gallons (227.3 liters) of combustible plus flammable liquids per room, provided no more than 30 gallons are Class I.
Also, the International Fire Code (adopted by the State of North Carolina) places limits on the amounts of flammable and combustible liquids stored in new or renovated buildings as the number of floors above grade increases. For some laboratories located on higher floors in new or renovated buildings, the flammable liquid storage limit per room might be less than 30 gallons. Contact EHS if you have questions about the flammable storage limits for your lab spaces.
Group A – Acids, Inorganics
Store large bottles of acid in special acid cabinets, cabinets under lab benches, or on low shelves. Place acids in plastic trays for secondary containment in case of breakage. Segregate inorganic and oxidizing acids from organic compounds including organic acids (e.g., acetic acid) and other combustible materials. Segregate nitric acid (>40%) from organic chemicals, including organic acids. Store acids separate from bases and other reducing agents. Inorganic salts, except those of heavy metals, may be stored in this group. Glacial acetic acid should be stored with flammable and combustible materials since it is combustible.
Group B – Bases
Segregate bases from acids and oxidizers on shelves near the floor. The preferred storage container for inorganic hydroxides is polyethylene instead of glass. Place containers in trays for secondary containment in the event of leakage or breaks.
Group C – Organic chemicals
Segregate organic compounds from inorganics. Organics and inorganics with NFPA 704 or HMIS reactive hazard rating of two (2) or less may be stored together. Chemicals with a reactive hazard rating of three (3) or four (4) are to be stored separately.
Group D – Flammable and Combustible Organic Liquids
Flammable and combustible liquid storage per room is limited to 10 gallons (37.9 liters) in open storage and use, 25 gallons (94.7 liters) in safety cans, and 60 gallons (227.3 liters) in flammable storage cabinets. Remember that only 30 gallons (113.6 liters) of Class I liquids are permitted per room, and International Fire Code restrictions might limit this even further if your lab is located on an upper floor in a new or renovated building. Store flammable and combustible materials away from sources of ignition such as heat, sparks, or open flames, and segregated from oxidizers.
Group E – Inorganic Oxidizers and Salts
Store inorganic oxidizers in a cool, dry place away from combustible materials such as zinc, alkaline metals, formic acid, and other reducing agents. Inorganic salts may also be stored in this group. Store ammonium nitrate separately.
Group F – Organic Peroxides and Explosives
Peroxides contain a double-oxygen bond (R1-O-O-R2) in their molecular structure. They are shock and heat sensitive (e.g. benzoyl peroxide), and readily decompose in storage. Store shock and heat-sensitive chemicals in a dedicated cabinet.
Some non-peroxide chemicals can readily form shock-sensitive, explosive peroxides when stored in the presence of oxygen. Examples include ethyl ether, tetrahydrofuran, and cumene. Dispose of, or use, these by their expiration date. See Chapter 12 for information on safe storage of peroxidizable compounds.
Common explosive compounds include 2,4,6-trinitrotoluene (TNT), nitroglycerin, and several metal fulminates and azides. 2,4,6-trinitrophenol, also known as picric acid, is normally sold as a saturated solution containing at least 40% water, and classified as a flammable solid. If allowed to dry to less than 10% water, picric acid becomes a DOT Class 1.1 explosive. Nitroglycerin in research is usually sold as a tincture mixed with alcohol, but if the alcohol evaporates, the result is explosive nitroglycerin. Please contact EHS if you use or handle compounds that are explosive or can become explosive with age or evaporation.
Group G – Reactives
Store water reactives in a cool dry place protected from water sources. Alkali metals (lithium, sodium, potassium, rubidium, and cesium) should be stored under mineral oil, or in waterproof enclosures such as glove boxes. A Class D fire extinguisher should be available in case of fire. Contact EHS if one is not available in your laboratory. As an added precaution, store containers in trays or other secondary containers filled with sand.
Pyrophorics (Air Reactives)
Store pyrophorics in a cool, dry place, and provide for an air tight seal. Store white or yellow phosphorous under water in glass stoppered bottles inside a metal can for added protection.
Group H – Cyanides and Sulfides
Cyanides and sulfides react with acids to release highly toxic gases. They must be isolated from acids and other oxidizers.
Group I – Carcinogens, Highly Toxic Chemicals, and Reproductive Toxins
A dedicated lockable storage cabinet in a “designated area” for carcinogens and highly toxic chemicals is the preferred storage method. Stock quantities of reproductive toxins are to be stored in designated storage areas. Use unbreakable, chemically resistant secondary containers. Post the storage cabinet with a sign stating “CANCER SUSPECT AGENT”, “HIGHLY TOXIC CHEMICALS”, or “REPRODUCTIVE TOXINS”. These signs are available at the EHS Safety Labels Page, and are depicted and described in Chapter 7. Maintain a separate inventory of all highly acute toxics, carcinogens, and reproductive toxins. See the Appendices to Chapter 7 for a listing of common carcinogenic and highly toxic chemicals. See the Appendix to Chapter 8 for a listing of reproductive toxins.
|Compatibility Group||Group Name||Chemical Class|
|Group A||Inorganic Acids,
|inorganic acids (except nitric), sulfur, arsenic, halides, sulfates, sulfites, thiosulfates, halogens, phosphorus, phosphates|
|Group B||Inorganic Bases||hydroxides, oxides, silicates, carbonates|
|Group C||Organics||alcohols, glycols, amines, amides, hydrocarbons, esters, aldehydes, phenol cresols, organic sulfides, organic acids|
|ethers, aliphatic solvents, aromatic solvents|
|Group E||Inorganic Oxidizers||borates, chromates, manganates, permanganates, chlorates, perchlorates, chlorites, hypochlorites, hydrogen peroxides, amides, nitrates, nitrites, azides|
|Group F||Organic Peroxides and Explosives||peroxides, azides, hydroperoxides|
|Group G||Reactives||air and water reactives, metals and hydrides|
|Group H||Cyanides, Sulfides||cyanides, cyanates, sulfides, carbides, nitrides|
|Group I||Highly Toxics,
|highly toxic compounds, carcinogens, mutagens, teratogens|