Sodium azide (CAS 26628-22-8): storage and disposal
University labs and pathology departments hold sodium azide as a solid and, far more often, as a preservative at around 0.1% in reagents, buffers and kits. It is fatal if swallowed and very toxic to aquatic life. What decides its handling is its reaction with metals and acids: it forms shock sensitive metal azides with lead, copper and brass, and acids release highly toxic, explosive hydrazoic acid. The solid and concentrated solutions go to manual enquiry.
- CAS number
- 26628-22-8
- Form
- Solid
- Storage class
- Toxic
- Signal word
- Danger
- Usual EWC code
- 16 05 06*
Acute toxicity
Hazardous to the environment
This chemical is a manual enquiry
This can become unstable or explosive, especially if it is old or has dried out. Nobody should move it until someone competent has looked at it, so we start with a conversation and usually a store assessment.
Azide: forms shock sensitive heavy metal azides and toxic gas with acids.
It cannot be priced through a form. Please do not open or move it. Call us or send an enquiry and we will talk through the safe next step, which is often a store assessment.
What to do this week
- Leave it where it is. If it looks old, crystalline or damaged, do not open or move it and keep people away from the shelf.
- Write down the label wording, the rough age and where it is stored, from a safe distance.
- Send us those details, and a photo if you can take one without touching it.
Safe storage in a school or lab
Metal contact decides where it goes. Lead, copper, brass and similar metals form shock sensitive azides with it over time, so a metal lid, a brass shelf fitting or a metal spatula left in the jar are the real hazards, far more than the shelf position. Plastic lids only, and no metal tools near it. Keep it in the locked toxic cabinet, away from acids such as hydrobromic acid, which release hydrazoic acid. Dichloromethane, chloroform and carbon tetrachloride belong well away too, as azides can form explosive azidoalkanes with them. Copper metal and aluminium powder also need separating. If an old bottle has a metal cap, or is undated, it stays where it stands: do not open or move it.
How to tell it has deteriorated
Look at the cap first. Crystals around a metal cap are the warning that stops everything, as they may be sensitive metal azide in place of the original salt. Corrosion on the cap or on metal fittings nearby points the same way, particularly on shelving that has held the bottle for a long time. The white solid itself gives few visual signs of age, so an intact looking interior offers no reassurance about the thread above it. Old kit reagents with this preservative rarely show anything at all. If you see crystals on a metal cap, or the bottle is old or undated, do not open it, turn the cap or move it. Get a specialist assessment before anyone goes near that shelf.
Contact with metal lids and shelving over time can create sensitive metal azides.
How it must be disposed of
This does not go through our standard collection route. It is arranged by manual enquiry, and never goes down the drain or into general waste.
First note whether the lid and any fittings touching the bottle are metal, the form held, the date of receipt and any crystals on the thread. Solid stock and concentrated solutions are not quoted online and are not accepted through the online quote path. Send a manual enquiry, and a store assessment is recommended. Do not open it, move it or try to make it safe. Preservative at 0.1% in kits may be less hazardous, but it should still be declared. The old habit of flushing azide solutions away with plenty of water must never be followed, because it can build explosive azides in lead and copper drain pipework. Pathology labs in human healthcare normally use code 18 01 06*.
| EWC code, laboratory chemicals | 16 05 06* |
|---|---|
| Discarded inorganic chemical, not a laboratory pack | 16 05 07* |
| Human healthcare setting | 18 01 06* |
| Hazardous waste | Yes |
The code depends on where the waste came from and what it is mixed with. Use the waste code finder to see why.
Do not store with
- OxidiserToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- AcidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
Named chemicals to keep apart
- 1,1,1-TrichloroethaneAzides can form explosive azidoalkanes with halogenated solvents.
- 1,2-DichloroethaneAzides can form explosive azidoalkanes with halogenated solvents.
- Aluminium powderAzides form shock sensitive metal azides with lead, copper, brass and similar metals.
- Carbon tetrachlorideAzides can form explosive azidoalkanes with halogenated solvents.
- ChloroformAzides can form explosive azidoalkanes with halogenated solvents.
- Copper metalAzides form shock sensitive metal azides with lead, copper, brass and similar metals.
- DichloromethaneAzides can form explosive azidoalkanes with halogenated solvents.
- Hydrobromic acidAzides release highly toxic and explosive hydrazoic acid with acids.
Show 16 more
- Hydrochloric acidAzides release highly toxic and explosive hydrazoic acid with acids.
- Hydroiodic acidAzides release highly toxic and explosive hydrazoic acid with acids.
- Iron filingsAzides form shock sensitive metal azides with lead, copper, brass and similar metals.
- Lead metalAzides form shock sensitive metal azides with lead, copper, brass and similar metals.
- Magnesium ribbonAzides form shock sensitive metal azides with lead, copper, brass and similar metals.
- MercuryMercury forms amalgams or unstable compounds with these materials.
- Nickel metalAzides form shock sensitive metal azides with lead, copper, brass and similar metals.
- Nitric acidAzides release highly toxic and explosive hydrazoic acid with acids.
- Perchloric acidAzides release highly toxic and explosive hydrazoic acid with acids.
- Phosphoric acidAzides release highly toxic and explosive hydrazoic acid with acids.
- Sulfuric acidAzides release highly toxic and explosive hydrazoic acid with acids.
- TetrachloroethyleneAzides can form explosive azidoalkanes with halogenated solvents.
- Tin metalAzides form shock sensitive metal azides with lead, copper, brass and similar metals.
- Trichloroacetic acidAzides release highly toxic and explosive hydrazoic acid with acids.
- TrichloroethyleneAzides can form explosive azidoalkanes with halogenated solvents.
- Zinc powderAzides form shock sensitive metal azides with lead, copper, brass and similar metals.
Common quantities we collect
Usually held as: solid, preservative solutions 0.1%.
Part-used bottles and full containers are both fine. Tell us the size and how many, and an estimate is enough for a first price.
Where it is commonly held
Hazard statements
- H300 Fatal if swallowed.
- H410 Very toxic to aquatic life with long lasting effects.
Precautionary statements
- P264 Wash hands and exposed skin thoroughly after handling.
- P270 Do not eat, drink or smoke when using this product.
- P273 Avoid release to the environment.
- P301+P316 IF SWALLOWED: Get emergency medical help immediately.
- P321 Specific treatment (see supplemental first aid instruction on this label).
- P330 Rinse mouth.
- P391 Collect spillage.
- P405 Store locked up.
- P501 Dispose of contents and container in accordance with local, regional, national and international regulations.
Substance as classified, dilutions may differ.
Questions
Our immunoassay kits list sodium azide at 0.1%. Do they need an enquiry too?
The online exclusion is aimed at the solid and concentrated solutions, but preservative in kits should still be declared, so list those reagents by name when you arrange collection. A weaker solution may be less hazardous than the solid, though it still must not go near a drain.
Old lab notes say small amounts of azide solution can simply go out with plenty of running water. Is that acceptable?
No, and it should not be done again. Azide can react with lead, copper and brass in old pipework to form shock sensitive metal azides, and water does not reliably prevent that. If you know this has happened in the past, tell your estates team.
Why does a metal cap on the bottle matter so much?
Contact with a metal lid over time can create sensitive metal azides on the thread, where turning the cap supplies the friction to set them off. The bottle may look fine from a distance. Leave it closed and unmoved, and mention the cap in your enquiry.
