Avoid contact with chemicals in all situations where chemicals are handled: Weighing out, pouring, routine lab work, transporting, cleaning up and disposal of waste.
For substances or containers with possible explosive qualities, age, storage temperature, light and air can be crucial for stability, so it is of utmost importance that these substances are not bought and stored in large quantities.
The Danish Emergency Management Agency (”Beredskabsstyrelsen”) has complete information on peroxides and formic acid.
If in doubt about high peroxide contents then be very careful about carrying and opening the container. A simple method of checking whether there are peroxides in e.g. ether is to mix a couple of mls with a potassium-iodide solution, add a couple of drops of diluted HCl and shake. The brown colour of iodine is a sure sign of peroxide.
The peroxide content can be checked with Peroxide Strips (Merck 1.10081.0001, level 1- 100 mg/L H2O2). Most peroxide-forming chemicals carry a stabiliser when delivered and chemical companies usually guarantee the shelf-life in unopened containers for three to five years from the production date. For chemicals not containing added stabilisers, there is a shorter shelf life.
Some peroxide-forming substances can reach explosive peroxide levels without a concentration of the solvent, and the general rule for substitution means that there should be a special reason for using diisopropylether.
According to the Danish “ADR” rules for transporting dangerous material, many of the ethers used routinely are classified as class 3 inflammable liquids. These rules (article 220.127.116.11.1) state that Class 3 liquids that easily form peroxides can only be transported by road when the peroxide content is no more than 0.3%, i.e. 3000mg/L. Such a high peroxide content will seldom be found in a laboratory, and unused peroxide-forming substances will normally be disposed of via the waste disposal system.
If in doubt – or it is known – that a substance has a high peroxide content (limit 100ppm), contact an Occupational Health and Safety representative/supervisor for further information, e.g. it could mean destroying the peroxides with an acid solution of ferrous- sulfate.
Containers with unstable chemicals should be labelled with date of purchase, date of opening, stability control, location, etc.
Unless the mixing process is under control do not mix:
Please note: Concentrated or fuming nitric acid + ethanol must not be used for cleaning glassware because of the danger of explosion.
Water-reacting substances react radically with water, often producing a lot of heat and in many cases producing gases. When mixing, pour the substance carefully into the water – never the other way round.
Examples of such substances are: