Malachite green (CAS 569-64-2): storage and disposal
Held as the oxalate salt for spore staining, malachite green is a green dye found in school and college microbiology prep rooms and in pathology and histology stores. Its classification is long: harmful if swallowed, serious eye damage, suspected of damaging the unborn child and very toxic to aquatic life with long lasting effects. That last entry is why it must never be rinsed away, and the pregnancy warning matters when deciding who handles the bottle.
- CAS number
- 569-64-2
- Form
- Solid
- Storage class
- Toxic
- Signal word
- Danger
- Usual EWC code
- 16 05 06*
Corrosive
Harmful or irritant
Serious health hazard
Hazardous to the environment
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
The suspected effect on the unborn child decides who should be handling this dye, so keep it in a locked cabinet with a stock record and let the technician in charge control access. Keep it apart from oxidisers and segregate acids to prevent incompatible contact and contamination. The oxalate salt is a dry crystalline solid, so containers should remain securely closed. If dye residue is present around the cap or thread, record the condition and refer it to competent staff for assessment. Spore stain bottles are usually small, which makes them easy to leave loose in a drawer. Store them upright in a tray with the powder, with eye protection kept at the cabinet, as eye damage is the immediate risk.
How to tell it has deteriorated
Look at the container first. A green ring at the cap, a green stain on the label or a smear on the shelf means seepage or careless handling, and a green label that has gone unreadable leaves an unknown bottle. The crystals are dark, so caking, a damp look or a crust in the thread show moisture has entered. A spore stain bottle that is noticeably lower than its record has lost liquid. Beyond that, this dye gives few visual signs of age that anyone should rely on, so the date of receipt and the stock record carry more weight. Stock whose record has been lost should be listed for collection, not opened to check.
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.
No part of this dye belongs in a sink, a drain or a general waste bin, and the aquatic classification is the reason that rule is absolute. Nobody should try to treat leftover stain before collection either. For the request, give the form (oxalate powder or spore stain), container size, setting and whether any bottle is leaking. A school, college or university store uses 16 05 06*, and hospital pathology clearing human healthcare stock uses 18 01 06*. Keep every container sealed and upright, with powder and liquid listed as separate lines so the carrier can pack them into compatible groups.
| 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: oxalate, spore stain.
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
- H302 Harmful if swallowed.
- H318 Causes serious eye damage.
- H361d Suspected of damaging the unborn child.
- H410 Very toxic to aquatic life with long lasting effects.
Precautionary statements
- P203 Obtain, read and follow all safety instructions before use.
- P264 Wash hands and exposed skin thoroughly after handling.
- P264+P265 Wash hands and exposed skin thoroughly after handling. Do not touch eyes.
- P270 Do not eat, drink or smoke when using this product.
- P273 Avoid release to the environment.
- P280 Wear protective gloves, protective clothing, eye protection and face protection.
- P301+P317 IF SWALLOWED: Get medical help.
- P305+P354+P338 IF IN EYES: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
- P317 Get medical help.
- P318 If exposed or concerned, get medical advice.
- 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
Why is malachite green stricter than other stains on the shelf?
Its classification includes a suspected effect on the unborn child as well as serious eye damage and long lasting harm to aquatic life. Access to the stock should therefore be controlled and recorded, and it should never be washed away.
Can an old spore stain bottle go back on the shelf after a check?
Only if it is dated, sealed, readable and matches the stock record. A bottle with a stained label, a crusted cap or unknown age is better listed for collection than reused.
Do we record malachite green oxalate differently from the powder of other dyes?
Name the oxalate salt and the form on the request, as the entry should describe what is actually in the container. The code depends on the setting, so say whether it came from a lab store or a healthcare service.
Who in a school should handle this dye?
The technician in charge should control access. Because the classification is for suspected damage to the unborn child, staff who are or may be pregnant should be told the dye is held and kept clear of it.
