Methenamine (CAS 100-97-0): storage and disposal

On a histology bench it is usually found beside the silver stain reagents, and that shelf is where it needs to be sorted out. As a flammable solid it belongs in a ventilated fire-resistant cabinet with spill containment, away from ignition sources. Oxidisers can ignite it or make a fire far more intense, and acids break it down, so neither should be in the same cabinet. A leak from incompatible acid or oxidising stock can also create a dangerous reaction. Keep the cap tight so that damp air stays out, and put gloves on to handle it, since it can sensitise skin. School and pharmacy holders should keep small jars together and label them.

Old methenamine can clump and cake after exposure to moisture, so a jar that was free-flowing powder and now forms a hard lump may have been exposed to damp air through a poor seal or during previous use. Other signs are a faded or stained label, a cap thread coated in powder, a lower level than the record shows and a missing date of receipt. Check histology kits for expiry marks printed by the maker and for loose reagent jars that have been separated from the kit. The substance gives few other visible signs of age. A jar that has fused to its cap should be left as it is and declared as it stands.

We arrange this by specialist collection. We do not publish a drain or general waste route for any chemical. It is normally packed in a flammable laboratory pack with compatible chemicals.

A lab pack is how it leaves: methenamine is packed with compatible organic solids, kept away from acids and oxidising stock. Waste code 16 05 06* is the usual description, with 18 01 06* in a human healthcare setting such as a pharmacy or hospital histology laboratory, and 16 05 08* for a discarded organic chemical outside a pack. Record the jar weight, whether it is caked and whether it belongs to a stain kit, since kits contain other reagents that must be listed separately. It is a flammable solid, so it is never burned or put in the bin.

Usually held as: solid, histology silver stains.

Tell us the container size and how many you hold. An estimate is enough to start with, and some items cannot be priced until someone has looked at them.