Indole-3-acetic acid (CAS 87-51-4): storage and disposal
Indole-3-acetic acid is the plant hormone powder, an auxin, held in school, college and university botany stores for rooting and growth practicals. It is classified as harmful if swallowed, as causing skin and serious eye irritation and as possibly causing respiratory irritation. Because only a pinch is used at a time, a jar can sit for many seasons and its condition becomes the question.
- CAS number
- 87-51-4
- Form
- Solid
- Storage class
- General
- Signal word
- Warning
- Usual EWC code, laboratory stock
- 16 05 06*
Harmful or irritant
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 general 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
The jar usually arrives in glass or amber glass, and that colour is there for a reason: indole compounds are sensitive to light and air, so the jar should stay in a closed cupboard, not on a bright plant room windowsill. Keep it dry, labelled and dated, with a tight cap, in a general store away from food grade supplies. The classified irritation of skin, eyes and airways means it should not be opened in an unventilated cupboard. Plant science stores often keep it beside other hormones and seed treatments, so make sure the label is legible and the stock record shows which jar is which.
How to tell it has deteriorated
A fresh jar holds an off-white or pale powder. With light and air, indole compounds tend to oxidise and take on a pink, tan or brown tint, so a jar that has turned noticeably coloured is an older one that has been exposed. Colour change is the chemical-specific sign worth recording. Beyond that, use the general checks: clumping from damp, a faded label, dust around the cap and an unknown date. A coloured powder is not a cause to open the jar. Record the colour, the label state and the cap condition for the description.
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 We do not publish a drain or general waste route for any chemical.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 general laboratory pack with compatible chemicals.
How it leaves the site is simple: by specialist collection, as hazardous waste in a lab pack with other solid organic chemicals, under waste code 16 05 06*, or 16 05 08* where it counts as discarded organic chemical outside a lab pack. A plant hormone is no less a chemical for being used on seedlings, so leftover powder and any stained jars should not be shaken onto compost, soil or a drain. Nobody should try to dissolve it first. Give the label wording, any colour change and the approximate quantity when requesting collection.
| 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.
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.
- H315 Causes skin irritation.
- H319 Causes serious eye irritation.
- H335 May cause respiratory irritation.
Precautionary statements
- P261 Avoid breathing dust, fume, gas, mist, vapours or spray.
- 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.
- P271 Use only outdoors or in a well-ventilated area.
- P280 Wear protective gloves, protective clothing, eye protection and face protection.
- P301+P317 IF SWALLOWED: Get medical help.
- P302+P352 IF ON SKIN: Wash with plenty of water.
- P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
- P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
- P319 Get medical help if you feel unwell.
- P321 Specific treatment (see supplemental first aid instruction on this label).
- P330 Rinse mouth.
- P332+P317 If skin irritation occurs: Get medical help.
- P337+P317 If eye irritation persists: Get medical help.
- P362+P364 Take off contaminated clothing. And wash it before reuse.
- 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.
Substance as classified, dilutions may differ.
Questions
Why has our indole-3-acetic acid gone pink?
Colour change in indole compounds usually follows exposure to light and air over time, so a pink or brown jar has aged. Record the colour and the label, keep the jar closed and in a dark cupboard, and ask for collection.
Can leftover powder go on the garden or compost?
No. It is classified as harmful if swallowed and as an irritant, and the jar is chemical waste. Putting it on soil or into compost is not a route. Keep the jar closed and include it in your collection request.
Does it need a fridge?
Only if your own procedures say so. The general storage advice is a dry, dark, labelled cupboard with a tight cap, away from food grade supplies. A fridge adds condensation risk, and food fridges should never hold it.
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