Sodium nitroprusside (CAS 14402-89-2): storage and disposal
Sodium nitroprusside dihydrate is held in college and university labs, pathology departments and some pharmacy stock as a dark red crystalline solid. It is classified as toxic if swallowed, and the complex releases cyanide. Light sensitivity and the company it keeps on the shelf decide how it is stored, and a spoiled bottle or solution is recognisable by a colour change.
- CAS number
- 14402-89-2
- Form
- Solid
- Storage class
- Toxic
- Signal word
- Danger
- Usual EWC code
- 16 05 06*
Acute toxicity
What to do this week
- 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 the items listed under "Do not store with".
- If you no longer need it, add it to your disposal list so it goes on the next collection.
Safe storage in a school or lab
Acids and oxidisers are the things to keep it away from, and the reason is the cyanide the complex can release. Put it in a locked cabinet with a stock record, apart from food and drink areas and from acid and oxidiser stock. Light breaks it down, so the bottle should stay in its original dark container and out of direct sun, whether it sits in a pharmacy cupboard or a lab fridge door. College and university labs often hold it for ketone and thiol tests, while a pathology department may keep a small amount for test work. Date it on arrival and record who has used it.
How to tell it has deteriorated
What a technician sees first on the shelf is usually the colour of the crystals or of any solution made from them. Fresh stock is deep red, and a solution that has turned blue has spoiled. Light also breaks the solid down, so a bottle kept in a bright window, or a clear one left out on a bench, may have changed colour. Check the label for fading, the cap for stains and the seal for failure. Cracked glass and caking are also worth noting. A bottle with no stock record or date of receipt is treated as old and described as it is.
How it must be disposed of
By specialist collection only. It never goes down the drain or into general waste. It is normally packed in a toxic laboratory pack with compatible chemicals.
Write down what the container is before anyone asks for a collection: the size, the form, whether any solution is held and what colour it now is, and whether the stock record is intact. A blue solution should be recorded as spoiled. The substance is a toxic complex that releases cyanide, so it stays out of any mixed box with acids or oxidisers. Waste code 16 05 06* fits a college or university lab, and a pharmacy or pathology holder in healthcare would use 18 01 06*. It does not go into a sink, a drain, a general waste bin or a skip, and nobody should try to treat it first.
| EWC code, laboratory chemicals | 16 05 06* |
|---|---|
| Discarded organic chemical, not a laboratory pack | 16 05 08* |
| 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
- 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 we collect
Usually held as: dihydrate.
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
- H301 Toxic if swallowed.
Precautionary statements
- P264 Wash hands and exposed skin thoroughly after handling.
- P270 Do not eat, drink or smoke when using this product.
- P301+P316 IF SWALLOWED: Get emergency medical help immediately.
- P321 Specific treatment (see supplemental first aid instruction on this label).
- P330 Rinse mouth.
- 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 must it stay away from acids?
Toxic stock is stored away from acids and oxidisers, and this complex is known to release cyanide. Keep the bottle in a locked cabinet on its own shelf, with the cap tight and a stock record beside it.
My solution has turned blue. What does that mean?
A blue solution shows the nitroprusside has spoiled. Do not keep it for use. Record the volume and label it clearly, then list it for collection, with the cap secure and the bottle stood upright in its cabinet.
Does light really matter for the solid?
Yes. Nitroprusside decomposes in light, so keep it in its original dark bottle, in a closed cabinet. An old, clear or uncapped container that has sat in sunlight should be recorded as degraded stock.
Is the pharmacy waste code different?
It can be. A human healthcare setting may use 18 01 06* in place of 16 05 06*, so state whether the stock is a pharmacy holding or a laboratory reagent when you enquire about collection.
