Sulfanilic acid (CAS 121-57-3): storage and disposal

The hazard that decides where it goes is the allergic skin reaction. A jar of sulfanilic acid should sit in a dry, labelled, well organised store, with the lid on firmly, and nobody should be reaching into an open tub with bare hands. School stores keep it for azo dye work, and pathology stores may hold it for nitrite testing, so it often sits alongside coloured reagent bottles that look similar. Label it clearly and date it on arrival. Keep food grade supplies away from it, and keep the jar out of food and drink areas.

Few visible signs of age show up here, so the container tells the story. Crystals that have clumped or caked suggest damp. A loose or cracked lid, powder on the outside of the jar or on the shelf, a faded or stained label and an unknown date of receipt are the typical faults. Coloured dust from neighbouring reagent bottles can make a jar look dirty. Powder on the shelf is the sign most worth acting on, because the hazard is a sensitiser. A jar that is dusty, undated or unlabelled should be left closed and listed for collection.

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 We do not publish a drain or general waste route for any chemical.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 general laboratory pack with compatible chemicals.

Say on the booking that it may cause an allergic skin reaction, so that whoever packs the load knows what the powder is. Record whether the jar holds loose crystals or caked lumps, how much is left and whether dust has escaped onto the outside. It is an organic chemical, so a discarded jar that is not in a lab pack usually takes 16 05 08*, and a healthcare setting such as a pathology department usually uses 18 01 06*, and the producer confirms the classification. It must never be tipped into a sink or drain or put in a bin or skip, and it must not be dissolved or neutralised first.

Usually held as: solid.

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.