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

p-Dimethylaminobenzaldehyde (CAS 100-10-7): storage and disposal

p-Dimethylaminobenzaldehyde is the powder behind Kovacs and Ehrlich reagents, found in school, college, university and pathology stores. It may cause an allergic skin reaction, causes serious eye irritation and is toxic to aquatic life with long lasting effects. Made-up reagent bottles and the dry powder are separate things. Which of them a store holds changes how the waste is listed.

CAS number
100-10-7
Form
Solid
Storage class
General
Signal word
Warning
Usual EWC code
16 05 06*
  • Harmful or irritant pictogramHarmful or irritant
  • Hazardous to the environment pictogramHazardous to the environment

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 general 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

Pathology and teaching stores often hold both the dry powder and one or two bottles of made-up Kovacs or Ehrlich reagent. Keep them on the same shelf by name, but list them separately, because they are different waste. The powder is general stock: keep it in a dry, labelled, well organised store, dated on arrival, and apart from food grade supplies. Because it can sensitise skin and is a risk to water life, a spill of powder on a bench should be handled by trained staff and never swept to a sink. Keep the lid tight, and wear gloves for weighing or moving the jar.

How to tell it has deteriorated

The powder starts out pale and tends to darken towards yellow or brown over time, particularly where light reaches it. A jar that has changed colour on a shelf by a window has been exposed for a long time, and a darker powder should be listed as aged stock. Look for clumping from damp, a stained cap thread, a faded label and a stock record that no longer matches the jar. Bottles of made-up reagent may leave a sticky ring at the neck and a stained label. Check receipt dates, because a jar of powder with no date at all is treated as unknown 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.

Say what is in each container before asking for a collection: dry powder, made-up reagent, or a mixture. The collector groups the powder in a lab pack with compatible organic solids and uses waste code 16 05 06* for a laboratory holder, or 18 01 06* in a human healthcare setting such as a hospital pathology department. Record the jar weight and the colour of the powder, and give each reagent bottle its own line with its label. Because it is toxic to aquatic life, it must not go down a sink or drain, and nobody should try to wash a jar out.

Waste codes and transport details for p-Dimethylaminobenzaldehyde
EWC code, laboratory chemicals16 05 06*
Discarded organic chemical, not a laboratory pack16 05 08*
Human healthcare setting18 01 06*
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.

Common quantities we collect

Usually held as: Kovacs and Ehrlich reagents.

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

  • H317 May cause an allergic skin reaction.
  • H319 Causes serious eye irritation.
  • H411 Toxic to aquatic life with long lasting effects.
Precautionary statements
  • P261 Avoid breathing dust, fume, gas, mist, vapours or spray.
  • P264+P265 Wash hands and exposed skin thoroughly after handling. Do not touch eyes.
  • P272 Contaminated work clothing should not be allowed out of the workplace.
  • P273 Avoid release to the environment.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • P302+P352 IF ON SKIN: Wash with plenty of water.
  • P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P321 Specific treatment (see supplemental first aid instruction on this label).
  • P333+P317 If skin irritation or rash occurs: Get medical help.
  • P337+P317 If eye irritation persists: Get medical help.
  • P362+P364 Take off contaminated clothing. And wash it before reuse.
  • P391 Collect spillage.
  • P501 Dispose of contents and container in accordance with local, regional, national and international regulations.

Substance as classified, dilutions may differ.

Questions

Is the powder waste the same as old Kovacs reagent waste?

No. The dry powder and a made-up reagent bottle are listed separately by their own label and contents. Do not combine them in one container, and declare each bottle as it stands.

Our powder has gone brown. Is it unsafe?

Darkening shows the powder has aged, usually from light or damp. The hazards listed still apply, including skin sensitisation. Stop using it for tests, keep it closed and add it to your waste list.

Why can't we wash residue from the jar into the sink?

The substance is toxic to aquatic life with long lasting effects, so a drain is not a route. Leave residue in the jar, put the lid on and send the jar with the collection.

Does a school store need to treat it as hazardous waste?

Yes. It is described as hazardous waste because of its classification, and the collector describes it accurately by name and strength. Give them the jar size, form and condition.

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 C9H11NO. EC number 202-819-0.

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