Ammonium iron(III) sulfate (CAS 10138-04-2): storage and disposal

Before anything else, look at the crystals through the glass: a dry, free-flowing bottle with a sound cap is the one you can leave alone. This is general class stock, so a dry, labelled, well organised store suits it, dated on arrival. Because it is classified as causing serious eye damage, handle it with the eyes in mind and keep it clear of food grade supplies. On a histology bench the working mordant solution gets its own label, name and date, and is not shelved as if it were the crystals. School and college stores usually hold the dodecahydrate, and a bottle left open takes up moisture from the room.

On the shelf, the first thing you see in good stock is pale violet crystals. A dull, powdery or yellow-brown surface means the crystals have changed, and damp, clumped stock or a crusted cap points to moisture getting past the seal. Solutions that have been made up for histology work can darken or throw a brown deposit as they age, and a mordant bottle with no date is as much a concern as one that looks wrong. General checks apply as well: a faded label and no record of when it arrived. Altered stock is still chemical waste, so keep it in its own container and label it. Do not top up a good bottle with it.

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.

Waste code 16 05 06* covers this item in a lab pack, and in a hospital histology department the healthcare entry 18 01 06* is the one that fits. Because the stock is classified as hazardous waste, the carrier will want a consignment note, which the collection team prepares from your description. The awkward part is usually the mix of forms: tubs of crystals alongside half-used mordant solution in unlabelled bottles. List each separately, with the strength of any solution if you know it. Nothing goes into a sink, a drain, a general waste bin or a skip, and no one should try to treat a solution before it leaves.

Usually held as: dodecahydrate, histology mordant.

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.