Imidazole (CAS 288-32-4): storage and disposal
Protein purification work leaves many university and pathology labs with a half-used tub of imidazole, a white crystalline solid. It is classified as harmful if swallowed, causes severe skin burns and eye damage, and may damage the unborn child. That last hazard means staff who are pregnant or planning a pregnancy need to know the tub is there before they handle it.
- CAS number
- 288-32-4
- Form
- Solid
- Storage class
- Toxic
- Signal word
- Danger
- Usual EWC code, laboratory stock
- 16 05 06*
Corrosive
Harmful or irritant
Serious health hazard
What to do this week
- Without moving anything that looks damaged, check the label is readable and write down the opened date if it is not already there.
- Check it is stored as toxic stock, and apart from anything listed under "Do not store with" on this page. If nothing is listed, that does not prove it is safe with everything.
- If you no longer need it, add it to your disposal list so it can be included in a collection.
Safe storage in a school or lab
Keep imidazole in a locked cabinet with a stock record, away from food and drink areas and apart from acids and oxidisers. Keep imidazole apart from acids and oxidising chemicals named on the safety data sheet, as reactions with them can give off heat or hazardous decomposition products. Labs that use it for purification columns often keep a working tub near the bench, so make sure that tub is closed after each use and not sharing a shelf with buffers that contain acid. Because the solid burns skin and eyes, the tub should sit below eye level, in a tray, with an intact label.
How to tell it has deteriorated
Crystals of this solid can take up moisture, so an old tub may show clumping, hard lumps or damp patches near the lid. Beyond that the solid gives few visible signs of its own. Check for stained or faded labels, powder caught in the thread that stops the cap seating, cracked plastic and any gap in the stock record. A tub that has been opened in a damp room and has set solid has been poorly sealed. Because the contents are classified as corrosive to skin and eyes, do not chip at a caked tub. Report it and leave it closed.
How it is disposed of
We arrange this by specialist collection. We do not publish a drain or general waste route for any chemical. It is normally packed in a toxic laboratory pack with compatible chemicals.
Say how much is left, whether it is the original tub and what condition the lid is in. Imidazole is waste with a reproductive classification, so the carrier needs an accurate hazardous description, normally using the laboratory chemical code, the discarded organic chemical variant outside a lab pack, or the healthcare code for a pathology holder. Leave it in its locked cabinet until collection. It must not go to a sink or general waste, and nobody should try to make it safer first. It is packed away from acids and oxidisers by the specialist carrier.
| Usual EWC code, laboratory stock | 16 05 06* |
|---|---|
| Discarded organic chemical, not a laboratory pack | 16 05 08* |
| Human healthcare setting | 18 01 06* |
| Usually classed as hazardous waste | Yes |
The code depends on where the waste came from and what it contains, and classifying it is the producer's duty. 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
- Acetic acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- Calcium hypochloriteToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Hydrochloric acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- Hydrogen peroxideToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Nitric acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- Potassium nitrateToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Potassium permanganateToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Sulfuric acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
Common quantities
Usually held as: solid.
Tell us the container size and how many you hold. An estimate is enough to start with, and some items cannot be priced until someone has looked at them.
Where it is commonly held
Hazard statements
- H302 Harmful if swallowed.
- H314 Causes severe skin burns and eye damage.
- H360D May damage the unborn child.
Precautionary statements
- P203 Obtain, read and follow all safety instructions before use.
- P260 Do not breathe dust, fume, gas, mist, vapours or spray.
- P264 Wash hands and exposed skin thoroughly after handling.
- P270 Do not eat, drink or smoke when using this product.
- P280 Wear protective gloves, protective clothing, eye protection and face protection.
- P301+P317 IF SWALLOWED: Get medical help.
- P301+P330+P331 IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.
- P302+P361+P354 IF ON SKIN: Take off immediately all contaminated clothing. Immediately rinse with water for several minutes.
- P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
- P305+P354+P338 IF IN EYES: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
- P316 Get emergency medical help immediately.
- P318 If exposed or concerned, get medical advice.
- P321 Specific treatment (see supplemental first aid instruction on this label).
- P330 Rinse mouth.
- P363 Wash contaminated clothing before reuse.
- 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
Why is imidazole stored like a toxic chemical?
It is classified as harmful if swallowed, as causing severe burns and as able to damage the unborn child. Locked storage, a stock record and separation from acids and oxidisers follow from that.
Should pregnant staff handle it?
The unborn child classification means they should be told it is held and should not handle it. The employer's risk assessment decides the arrangements, which are outside this site.
What do we do with a caked, old tub?
Do not break it up or chip at it. Check the label and cap, keep the tub closed in the locked cabinet, record its condition in the stock book and request a collection.
