Methyl green (CAS 7114-03-6): storage and disposal

Because its formula includes zinc, keep it in a closed, labelled jar in a dry general store, away from acids and from the reducing and oxidising shelves, and record on the jar that it is a zinc-containing dye. The powder irritates the airways, so avoid raising dust. If the cap thread is contaminated, leave the deposit undisturbed and record its condition. Date it on arrival. Methyl green is usually used alongside pyronin, which is a different dye with a different classification, so keep their jars and records apart even though the two are mixed at the bench. A tray beneath the jar will show spilled green powder at once.

Powder that is dry and runs freely, with a clean thread, is the normal state. A green dusting on the shoulder of the jar, a stained label or powder on the shelf shows the cap has been closing on grit or has failed. Lumps, a damp look and a hard cake mean moisture has entered. This dye gives no specific sign of age, so beyond these checks it gives few visual clues, and the paperwork has to carry the evidence: unreadable label, missing date of receipt, record that no longer matches. An unlabelled green jar should be left sealed and listed as unknown.

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.

How it leaves the site is by collection, and the description should say that the dye contains zinc, as well as the form, jar size and any damage to the lid. A university or laboratory store uses 16 05 06*, and a human healthcare pathology service clearing it uses 18 01 06*. Because it irritates skin, eyes and airways, a jar with powder spilled on the outside should be bagged on its own. It is not emptied into a sink, a drain or general waste, and a green stain on a bench is not a reason to rinse the jar. Keep it sealed and upright.

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.