Time-Sensitive Chemicals

Aftermath of a waste room explosion at U of Minnesota caused by mismanaged Peroxide-forming solvent.

Introduction

Some lab chemicals can develop additional hazards over time which are different from their hazards in the original formulation. Time-Sensitive Chemicals represent an additional hazard to lab workers and can be very expensive to dispose of once additional hazards have developed. There have been MANY documented cases of injury caused by these materials.  It is extremely important that these chemicals are identified, managed properly, and disposed of when they become expired or on reaching the recommended maximum storage time.  This webpage describes best practices for managing Time-Sensitive chemicals. 

Resources

Visit the Peroxide Forming Chemicals webpage for detailed information on managing that class of chemicals.  

Visit the Other Time-sensitive Chemicals webpage for more information about other classes of Time-sensitive chemicals.

See the printable TIME-SENSITIVE CHEMICALS FACT SHEET for summarized information.

See the TIME-SENSITIVE CHEMICALS TABLE for a list of time-sensitive compounds.  The listed time-sensitive chemicals are not comprehensive. Read the Safety Data Sheets of your chemicals and look for time-sensitive hazard statements such as “May form explosive peroxides".

Best Practices:

• Purchase chemicals containing inhibitor whenever possible.
• Purchase only what is immediately needed in the smallest practical quantity.
• Do not open a new bottle until needed and always use the oldest containers first.
• Store all containers of the same compound close together for easier management.
• Wipe clean the cap threads on containers before closing.
• Promptly request disposal of any excess or expired chemicals via the OEHS Hazardous Waste program. Email hazwaste@tulane.edu with the waste information.  Request pickup as soon as possible when required.  Peroxide-Forming chemicals must be tested for peroxides within 2 weeks of the pickup request.  Include the test date and concentration of peroxides detected in the waste request, in addition to the information normally required in pickup requests.
• Do not mix Time-sensitive Chemicals with other wastes.
• If a Time-Sensitive Chemical container is very old and/or found to be far past expiration without testing for a long time, or fails visual inspection, do not touch it.  Contact OEHS immediately for guidance.

Container Management

The date received, expiration date or maximum storage time, and room sub-location of Time-Sensitive Chemicals must be logged into your Chemical Inventory.  Always label each container with the date received and the date opened.  Use a Peroxide-Former Label to track testing of each container of Peroxide-Forming chemical.  Make calendar reminders to inspect and/or test these chemicals according to the recommended frequency.

Container Inspection

Peroxide crystals in a solvent container.

Time-Sensitive Chemical containers MUST be regularly inspected for increased hazards.  This is a careful visual inspection of the materials without moving or disturbing the container.  Follow the specific instructions for each type of Time-sensitive Chemical.  If the container passes inspection, it can be picked up and used or tested.  Shine a flashlight through dark or amber bottles to more easily see precipitates.

When inspecting containers of Peroxide-Forming Chemicals, the presence of any precipitation or crystal formation could indicate that organic peroxides have accumulated to a dangerous extent.  DO NOT MOVE the container and contact OEHS immediately if you see any of the following: 

• Visible solid precipitate in the liquid

• Very fine, spun glass-wool appearance in the liquid

• Incrustation around the cap

• Layer separation (an oily viscous layer)

• Visible discoloration or Cloudiness

• Very old container (yellowed label or made by a manufacturer from many years ago)  

Real Life Examples of Incidents and Injuries from Time-Sensitive Chemicals:

Chemical Waste Explosion - Solvent bottle (Peroxide Former)

Chemical Waste Explosion - Residue on bottle (Peroxide Former)

Peroxide Explosion in a RotoVap

Peroxide Former (2-Butanol) Explosion

Peroxide Former (Diethyl Ether) Explosions

Nitric Acid Container Failure at U of Texas

Nitric Acid Container Failure at U of Florida

Four lab workers sickened by phosgene exposure from Chloroform

Suspected Phosgene exposure from Chloroform

Dry Picric Acid Disposal from Lab

Picric Acid Disposal and Detonation 

Anhydrous Hydrogen Fluoride Cylinder Failure

Explosion of Sodium Metal Stored Under Oil

Potassium Metal Explosion

References

1. Kelly, R.J. Review of Safety Guidelines for Peroxidizable Organic Compounds. Chemical Health and Safety 1996 (Sept/Oct), 28-36.
2. Bretherick’s Handbook of Reactive Chemical Hazards, 7^th ed.
3. Prudent Practices in the Laboratory. Washington, D.C.: The National Academies Press.
4. Clark, D., Peroxides and Peroxide - Forming Compounds, Journal of Chemical Health and Safety 2001, 8 (5), 12-21.
5. Peroxide Forming Solvents. Millipore Sigma.
6. Bailey, J., D. Blair, L. Boada-Clista, D. Marsick, D. Quigley, F. Simmons, and H. Whyte, Management of time-sensitive chemicals (I): Misconceptions leading to incidents. Chemical Health & Safety 2004 11 (5), 14-17. DOI: 10.1016/j.chs.2004.05.014
7. Bailey, J., D. Blair, L. Boada-Clista, D. Marsick, D. Quigley, F. Simmons, and H. Whyte, Management of time-sensitive chemicals (II): Their identification, chemistry and management. Chemical Health & Safety 2004 11 (6), 17-24. DOI: 10.1016/j.chs.2004.05.017