Tris (CAS 77-86-1): storage and disposal

Skin, eye and respiratory irritation decide where it goes: a closed tub on the general shelf, labelled and dated on arrival, apart from food grade supplies and not stored where powder could be disturbed. Tris is an amine, so keep it away from aldehyde fixatives and stock on the histology bench, such as formaldehyde, because it reacts with them. Strong acids also belong on a separate shelf. Solid and 1 M buffer should be recorded separately in the stock list, as a bottle of colourless buffer is easily mistaken for water or for another buffer. School and college stores usually hold small tubs, so check each one for a legible label and date.

Fresh Tris powder is white and free flowing. A tub that has been left open may form lumps or a damp, caked block, and the cap area may show crust or staining. The solid gives few other visible signs, so a normal appearance does not prove the stock is recent. Buffer solution that was clear when made can turn cloudy, show specks or grow a film as microbes enter, particularly in bottles dipped into many times. Labels fade quickly on bench bottles, and an unlabelled colourless liquid is the real hazard. General checks also apply, including cracked containers and an unknown date of receipt. Such items should be left closed, recorded and held 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 We do not publish a drain or general waste route for any chemical.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.

Pouring it away is not an option: Tris powder and Tris buffer must not go into a sink, a drain, a general waste bin or a skip, and nobody should try to treat the solution first. Specialist collection is the only route. Because the substance is classified, solid stock is normally described as hazardous and a consignment note follows it, which a school or college should file with its other waste paperwork. The producer assesses made-up buffer on its own composition. The collector groups bottles with compatible items. Record whether each container is solid or 1 M buffer, its size and any additives, since used buffers often contain other reagents.

Usually held as: solid, 1 M buffer.

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.