Ammonium acetate (CAS 631-61-8): storage and disposal

Chromatography buffers and pathology work leave college, university and pathology stores with a tub of ammonium acetate, a white crystalline solid that is very easy to leave open. It is not classified as hazardous on the sources we checked, but it remains a chemical waste that needs accurate description. The usual story is a damp, smelly tub that nobody remembers opening.

CAS number: 631-61-8
Form: Solid
Storage class: General
Usual EWC code: 16 05 09

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 general 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

Start with the container: a tight cap matters because this salt pulls water from the air and slowly gives off ammonia. Ammonium acetate sits in a dry, labelled, well organised store, dated on arrival, apart from food grade supplies. Keep it away from strong alkalis, namely sodium hydroxide and potassium hydroxide, which release ammonia gas from ammonium salts. Chlorates, such as potassium chlorate and sodium chlorate, can form unstable ammonium chlorate with it, and sodium nitrite can react violently with it on heating. In a college store this means a separate cabinet from the oxidisers and the alkali shelf.

How to tell it has deteriorated

Smell and dampness are what a technician finds first. An old tub of ammonium acetate often smells faintly of ammonia and acetic acid, because the salt slowly loses ammonia, and the crystals turn wet or pasty as they absorb water. A solid lump at the bottom or crust at the neck shows the same thing at a later stage. Because the composition drifts, an old tub is no longer the pure salt on the label. Check the label, the date and the cap. A jar topped up from another source, or one in which the salt has dissolved in its own moisture, is mixed stock.

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 non-regulated or low hazard laboratory pack with compatible chemicals.

A wet, smelling tub of this salt is not classified as hazardous on the sources we checked, but it is still chemical waste and is described by what it is. Say whether it is dry or damp, how much is left and whether the label is readable. It does not belong in a bin, down a drain or in a skip, and nobody should add alkali or acid to a tub in order to deal with the smell. A transfer note covers it, and healthcare entries apply to pathology. The carrier packs it away from alkalis, chlorates and nitrites.

Waste codes and transport details for Ammonium acetate
EWC code, laboratory chemicals	16 05 09
Human healthcare setting	18 01 07
Hazardous waste	No

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

Named chemicals to keep apart

Potassium chlorateChlorates and ammonium salts can form unstable ammonium chlorate.
Potassium hydroxideStrong alkalis release ammonia gas from ammonium salts.
Sodium chlorateChlorates and ammonium salts can form unstable ammonium chlorate.
Sodium hydroxideStrong alkalis release ammonia gas from ammonium salts.
Sodium nitriteNitrites and ammonium salts can react violently on heating.

Common quantities we collect

Usually held as: solid.

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

Questions

Why does our ammonium acetate smell of ammonia?

The salt slowly loses ammonia and takes in water from the air, so old stock smells and goes damp. It means the cap has not been sealing, and the contents are no longer the pure salt.

What should it be kept apart from?

Strong alkalis such as sodium hydroxide, chlorates and sodium nitrite. Alkalis release ammonia gas, chlorates can form unstable ammonium chlorate, and nitrites can react violently on heating.

Is it classed as hazardous waste?

It is not classified as hazardous on the sources we checked, but it remains a chemical waste. It is described accurately, goes with a transfer note and is collected by specialist carrier.