Trichloroacetic acid (CAS 76-03-9): storage and disposal
Trichloroacetic acid is held as solid crystals and as a 10% solution in university labs, pathology and histology departments and clinics. It causes severe skin burns and eye damage and is very toxic to aquatic life with long lasting effects. The solid takes up moisture strongly and the solution decomposes over time, so the condition of a jar often tells a holder more than the date does.
- CAS number
- 76-03-9
- Form
- Solid
- Storage class
- Acid
- Signal word
- Danger
- Usual EWC code
- 16 05 06*
Corrosive
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 acid 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
Look at the jar without lifting or opening it. Loose crystals are normal, while damp clumps or a wet mass may indicate that moisture has entered through the closure. The solid absorbs moisture strongly and can turn to a wet mass, so keep the lid fully seated and never leave the jar open on a bench. It is corrosive, so it sits low down on an acid-resistant tray in a ventilated corrosive store, away from sulfides, bleach compounds, cyanides and chlorates. A made-up 10% solution on a histology bench or in a clinic cupboard should carry a date, since it decomposes in solution over time. Alkalis belong on another shelf.
How to tell it has deteriorated
A wet or sticky mass in the jar is the first sign, and so is liquid pooled in the bottom or a damp film inside the lid. The solid takes up moisture so strongly that a badly closed jar can set into a single lump. The 10% solution breaks down over time, which means a very old bottle is no longer the strength on its label. Further checks are a perished cap, crust around the neck, cracked containers, a faded label and an unknown date of receipt. Anything wet, undated or leaking should stay upright on its tray and be listed for collection.
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 corrosive acid laboratory pack with compatible chemicals.
Record whether each container holds dry crystals, a wet mass or the 10% solution, how much is left and whether the lid has stuck down. Wet or sticky stock is awkward to lift, so say so when booking. Because the acid is very toxic to aquatic life with long lasting effects, it must never go into a sink or drain, and it must not go in a bin or skip either. It must not be diluted or neutralised first. A clinic or pathology store describes it under 18 01 06*. The collector groups it with other acids and keeps it away from cyanides and sulfides.
| 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
- FlammableOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
- AlkaliAcids and alkalis react with strong heat and spattering if they meet.
- OxidiserMany oxidisers release toxic gas or become unstable in contact with acid.
- ToxicToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
Named chemicals to keep apart
- AcetoneOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
- Ammonia solutionAcids and alkalis react with strong heat and spattering if they meet.
- Ammonium sulfide solutionSulfides release toxic hydrogen sulfide gas with acids.
- Calcium hypochloriteHypochlorites release toxic chlorine gas in contact with acids.
- Chloramine THypochlorites release toxic chlorine gas in contact with acids.
- EthanolOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
- FormalinToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- HexaneOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
Show 16 more
- Hydrogen peroxideMany oxidisers release toxic gas or become unstable in contact with acid.
- Iron(II) sulfideSulfides release toxic hydrogen sulfide gas with acids.
- Mercury(II) chlorideToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- MethanolOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
- Potassium chlorateChlorates and strong acids can form explosive chlorine dioxide.
- Potassium cyanideCyanides release highly toxic hydrogen cyanide gas with acids.
- Potassium ferricyanideHeating or strong acids can release toxic hydrogen cyanide from these complexes.
- Potassium ferrocyanideHeating or strong acids can release toxic hydrogen cyanide from these complexes.
- Potassium hydroxideAcids and alkalis react with strong heat and spattering if they meet.
- Sodium azideAzides release highly toxic and explosive hydrazoic acid with acids.
- Sodium chlorateChlorates and strong acids can form explosive chlorine dioxide.
- Sodium cyanideCyanides release highly toxic hydrogen cyanide gas with acids.
- Sodium dichloroisocyanurateHypochlorites release toxic chlorine gas in contact with acids.
- Sodium hypochloriteHypochlorites release toxic chlorine gas in contact with acids.
- Sodium nitriteNitrites release toxic nitrogen oxides with acids.
- Sodium sulfideSulfides release toxic hydrogen sulfide gas with acids.
Common quantities we collect
Usually held as: solid, 10% solution.
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
- H314 Causes severe skin burns and eye damage.
- H410 Very toxic to aquatic life with long lasting effects.
Precautionary statements
- P260 Do not breathe dust, fume, gas, mist, vapours or spray.
- P264 Wash hands and exposed skin thoroughly after handling.
- P273 Avoid release to the environment.
- P280 Wear protective gloves, protective clothing, eye protection and face protection.
- 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.
- P321 Specific treatment (see supplemental first aid instruction on this label).
- P363 Wash contaminated clothing before reuse.
- 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
What happens to trichloroacetic acid crystals if the lid is left loose?
The solid absorbs moisture strongly and can turn into a wet mass, which is still corrosive and much harder to handle. A jar in that state should be capped, kept upright on its tray and listed for collection, not scraped or broken up.
How long can a 10% solution be kept?
No shelf life is given, but the acid decomposes in solution over time, so an old bottle will not match its label. Date every bottle on arrival and list any that are undated, cloudy or leaking for collection rather than keeping them.
Why can a 10% solution not go down the drain?
The acid is classified as very toxic to aquatic life with long lasting effects, and a weaker solution may be less hazardous but is still chemical waste. It must not go into a sink or drain and goes by specialist collection.
