Diphenylamine (CAS 122-39-4): storage and disposal
A small jar of pale crystals at the back of a prep room cupboard is usually how diphenylamine turns up, kept as the base of a redox indicator. It is classified as toxic if swallowed, in contact with skin and if inhaled, and very toxic to aquatic life. Because a jar is rarely used up, it tends to outlive the teacher who ordered it, and that age is what shapes how it is handled.
- CAS number
- 122-39-4
- Form
- Solid
- Storage class
- Toxic
- Signal word
- Danger
- Usual EWC code, laboratory stock
- 16 05 06*
Acute toxicity
Serious health hazard
Hazardous to the environment
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 it away from oxidisers and acids, because toxic stock beside them can give off hazardous vapours or gas if a container leaks or cracks. In a prep room that means a locked cabinet for toxic stock, not the open shelf where indicator powders are normally lined up. The powder looks ordinary, which is exactly why the stock record matters as much as the lock: note who holds the key and when the jar last left the cabinet. Diphenylamine is also classified for organ damage after prolonged or repeated exposure, so a jar on a busy bench is a poor idea. Keep it clear of food and drink areas, including staff room fridges and shared workrooms used by colleges and universities.
How to tell it has deteriorated
Look at the jar before the contents. A stained cap, a faded label or powder dusted around the neck suggests the seal has failed, and a missing stock record means nobody can say how old the jar is. The crystals themselves start pale. After years of light and air they darken towards grey or brown, and that colour change is the one chemical-specific sign worth writing down. Darkening tells you the stock is old and probably unwanted, nothing more. Do not open a jar to look closer, and do not combine two jars into one to tidy up. Record the colour, the label state and the cap condition so the collection can describe the jar accurately.
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.
It leaves the site by specialist collection, packed with other toxic organic solids in a lab pack. Waste code 16 05 06* fits an ordinary laboratory chemical, and 16 05 08* is used where the jar counts as discarded organic chemical outside a lab pack. Because it is very toxic to aquatic life, no part of the jar or its dust may go near a drain, and nobody should try to treat it first. Keep the original container and label, note roughly how much remains, and keep it apart from oxidisers and acids until the day it is collected.
| Usual EWC code, laboratory stock | 16 05 06* |
|---|---|
| Discarded organic chemical, not a laboratory pack | 16 05 08* |
| 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
- H301 Toxic if swallowed.
- H311 Toxic in contact with skin.
- H319 Causes serious eye irritation.
- H331 Toxic if inhaled.
- H373 May cause damage to organs through prolonged or repeated exposure.
- H410 Very toxic to aquatic life with long lasting effects.
Precautionary statements
- P260 Do not breathe dust, fume, gas, mist, vapours or spray.
- P261 Avoid breathing dust, fume, gas, mist, vapours or spray.
- P262 Do not get in eyes, on skin, or on clothing.
- P264 Wash hands and exposed skin thoroughly after handling.
- P270 Do not eat, drink or smoke when using this product.
- P271 Use only outdoors or in a well-ventilated area.
- P273 Avoid release to the environment.
- P280 Wear protective gloves, protective clothing, eye protection and face protection.
- P301+P316 IF SWALLOWED: Get emergency medical help immediately.
- P302+P352 IF ON SKIN: Wash with plenty of water.
- P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
- P316 Get emergency medical help immediately.
- P319 Get medical help if you feel unwell.
- P321 Specific treatment (see supplemental first aid instruction on this label).
- P330 Rinse mouth.
- P361+P364 Take off immediately all contaminated clothing. And wash it before reuse.
- P391 Collect spillage.
- P403+P233 Store in a well-ventilated place. Keep container tightly closed.
- P405 Store locked up.
- P501 Dispose of contents and container in accordance with local, regional, national and international regulations.
- P203 Obtain, read and follow all safety instructions before use.
- P264+P265 Wash hands and exposed skin thoroughly after handling. Do not touch eyes.
- P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
- P318 If exposed or concerned, get medical advice.
- P337+P317 If eye irritation persists: Get medical help.
Substance as classified, dilutions may differ.
Questions
Can a jar of diphenylamine that has turned dark brown still be collected?
Collection is arranged in the same way. Darkening is a sign of age and long exposure to light and air, not a separate waste category. Leave the lid on, keep the jar in its locked cabinet, and record the colour and the cap condition so the stock is described accurately as hazardous waste.
Where should diphenylamine sit if our prep room has no locked cabinet?
It is classified as toxic, so the standard answer is a locked cabinet with a stock record, away from food and drink areas, acids and oxidisers. If the room has no such cabinet, say so when you request collection and avoid leaving the jar on an open indicator shelf in the meantime.
Why is such a small jar classed as hazardous waste?
The classification covers toxicity by swallowing, skin contact and inhalation, organ damage after repeated exposure, and long lasting harm to aquatic life. Quantity does not change that classification, so even a nearly empty jar goes out as hazardous waste with an accurate description.
Do we need to separate it from other indicator powders in the same cupboard?
Yes. Most indicator powders are not classified as toxic by several routes, so diphenylamine should be taken out of the general run and kept with toxic stock. Any oxidising salts or acids in the same cupboard are the main reason for moving it.