Urea (CAS 57-13-6): storage and disposal

Damp is the enemy of this stock. Keep urea in a dry, labelled, well organised store, in a jar with a tight lid, dated on arrival, and keep it apart from any food grade or garden supplies that look similar. Pathology and pharmacy holders often have small amounts in reagent kits, and these are best kept with the kit label so the contents are not lost. Do not leave the lid loose after weighing out. A school store that keeps urea on an open shelf near a basin or a window will see caking sooner than one that keeps it in a closed cupboard.

A jar of free-flowing crystals that has set into a hard lump has taken in water, and caked urea cannot be spooned out. A smell of ammonia on opening points the same way, since damp urea slowly breaks down. Damp patches, a cap that has seized, a wet label, a lower level than the record and a missing receipt date are the other signs. The crystals themselves stay white, so colour is less useful than smell and texture. A jar that is caked or smells of ammonia is listed as aged stock and is not used for teaching.

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 caked jar is listed as found, never broken up or dissolved to get it moving, and it does not go into a sink, a bin or a skip. It is not classified as hazardous on the sources we checked, so the code is 16 05 09 in a laboratory and 18 01 07 in a pharmacy or pathology lab, with a waste transfer note for the movement. Say how heavy the jar is, whether it has set hard or smells of ammonia, and whether it came from a reagent kit, because kit contents can differ from pure urea. A specialist collection places it among compatible solids in a lab pack.

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.