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Chemical collection and stock control for UK schools, universities and hospitals

Dimethylglyoxime (CAS 95-45-4): storage and disposal

In a school or college chemistry store, dimethylglyoxime is the white powder kept for the nickel test, sometimes alongside a bottle labelled as 1% in ethanol. It is classified as a flammable solid and toxic if swallowed. Small amounts last for years, so most departments hold stock long past its use, and the form on the shelf decides how it is described.

CAS number
95-45-4
Form
Solid
Storage class
Flammable
Signal word
Danger
Usual EWC code
16 05 06*
  • Flammable pictogramFlammable
  • Acute toxicity pictogramAcute toxicity

What to do this week

  1. Check the label is readable and write down the opened date if it is not already there.
  2. Check it is stored as flammable stock and apart from the items listed under "Do not store with".
  3. 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 container tells you which form you have, and the two forms are stored slightly differently. The powder is a flammable solid, so it goes in the flammable cabinet away from ignition sources, with oxidisers kept elsewhere, and it is toxic if swallowed, so it should not sit on an open shelf in a teaching lab. The 1% in ethanol bottle also belongs in the flammable cabinet, since the solvent adds to the fire risk. Keep acids and corrosive stock away from both forms. Label any solution with its contents and date, because unlabelled indicator bottles are common in school stores.

How to tell it has deteriorated

Powder gives few visible signs of age, so look at the container: a split label, a cracked bottle, clumping where damp has got in, or powder dusted around the cap. The ethanol solution is easier to read. Evaporation leaves a low level and pale crystals at the neck and thread, because the solid comes out of solution as the solvent leaves. A stuck cap is the usual result. A bottle with no date or no label is the most common fault in school stores. Record what you see, and do not scrape the crystals off or open a stuck bottle.

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 flammable laboratory pack with compatible chemicals.

How it leaves the site depends on the form. Powder goes by specialist collection as a flammable solid that is toxic if swallowed, grouped in a lab pack with compatible organic solids, under waste code 16 05 06*, or 16 05 08* where it counts as discarded organic chemical outside a lab pack. The ethanol solution travels as a separate item, described by both the solid and the solvent. Neither form should go to a drain or into the general bin, and nobody should try to evaporate the solution to leave the powder. List each container separately with its label wording.

Waste codes and transport details for Dimethylglyoxime
EWC code, laboratory chemicals16 05 06*
Discarded organic chemical, not a laboratory pack16 05 08*
Hazardous wasteYes

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

  • OxidiserOxidisers can ignite flammable materials or make a fire far more intense.
  • AcidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • CorrosiveA leak of corrosive stock can break down flammable containers and feed a fire.

Named chemicals to keep apart

  • Acetic acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Calcium hypochloriteOxidisers can ignite flammable materials or make a fire far more intense.
  • Hydrochloric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Hydrogen peroxideOxidisers can ignite flammable materials or make a fire far more intense.
  • Nitric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Potassium nitrateOxidisers can ignite flammable materials or make a fire far more intense.
  • Potassium permanganateOxidisers can ignite flammable materials or make a fire far more intense.
  • Sulfuric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
Show 2 more
  • Thionyl chlorideA leak of corrosive stock can break down flammable containers and feed a fire.
  • Zinc chlorideA leak of corrosive stock can break down flammable containers and feed a fire.

Common quantities we collect

Usually held as: solid, 1% in ethanol.

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

  • H228 Flammable solid.
  • H301 Toxic if swallowed.
Precautionary statements
  • P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
  • P240 Ground and bond container and receiving equipment.
  • P241 Use explosion-proof electrical, ventilating and lighting equipment.
  • P264 Wash hands and exposed skin thoroughly after handling.
  • P270 Do not eat, drink or smoke when using this product.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • P301+P316 IF SWALLOWED: Get emergency medical help immediately.
  • P321 Specific treatment (see supplemental first aid instruction on this label).
  • P330 Rinse mouth.
  • P370+P378 In case of fire: Use suitable extinguishing media to extinguish.
  • 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

Do the powder and the 1% ethanol solution need separate entries?

Yes. They are different containers with different descriptions, and the solution also carries the solvent. List each bottle with its label wording and approximate quantity so the collection can group and describe them properly.

Why is dimethylglyoxime stored in a flammable cabinet?

It is classified as a flammable solid, and as a toxic one if swallowed. That puts it with flammable stock away from ignition sources, and the ethanol solution adds a flammable solvent. An open shelf in a teaching lab is not suitable.

What is the white crystal ring at the top of an old solution bottle?

It is the solid coming out as the ethanol evaporates through a worn cap. It shows the seal is no longer good and the level has dropped. Do not scrape it off or force the cap. Record it and have the bottle collected.

Guidance only. Check your own risk assessment and your supplier's safety data sheet.

Hazard data source: PubChem GHS Classification, retrieved 31 Oct 2026. Formula C4H8N2O2. EC number 202-420-1.

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