“Legacy” chemicals are often inherited chemical stocks from previous occupants or team members. Often these chemicals are left sitting in the back of cabinets, in desiccators, or drawers for many years, unnoticed and unused. It is not unusual that these chemicals are grouped based upon the name(s) of the previous owner(s) and as a result are sometimes stored with incompatible chemicals. In addition to taking up valuable space, some of these chemicals can become dangerous as they age. Small leaks that go unnoticed could cause violent reactions and generate toxic fumes.
Below is a short list of chemicals that pose serious hazards when stored for an extended period of time:
Picric Acid (solid or as part of a premade stain or solution): Pure picric acid is a shock-sensitive explosive. For that reason it is shipped wet (or in solution), and it should be checked for its water content quarterly. Do NOT open a bottle that appears to be dry or that has not been checked for a long time, immediately notify EHLS.
Perchloric acid: Whereas 70% perchloric acid is stable, many of its salts (perchlorates) are shock-sensitive explosives. Old perchloric acid bottles may have formed crystals that are explosive.
Hydrofluoric acid: Hydrofluoric acid (HF) is stored in plastic bottles. The plastic material deteriorates with time and becomes brittle. There have been cases where bottles broke as they were picked up. HF is highly toxic - a minor exposure can have serious consequences.
Diethyl ether (or short ethyl ether): Diethyl ether forms explosive peroxides over time. Bottles should be dated when received and checked for peroxide regularly. Old bottles that have not been checked may contain significant amounts of peroxides. Other commonly found peroxide formers are isopropanol, isoamyl alcohol, tetrahydrofuran, and dioxane.
Hydrazine and other corrosives can cause corrosion of the container lid causing a leak that allows toxic vapors to escape.
Other chemicals may not become more hazardous as they age, but they degrade rendering them useless.
We strongly encourage all laboratory groups to inventory the chemicals in your spaces and dispose of old chemicals as well as any chemicals not in use. There is no charge for disposal; however, labs can be held responsible for property damage that occurs due to unmanaged legacy chemical stocks.