Eosin Y (CAS 17372-87-1): storage and disposal

Powder sits happily on a dry general shelf, capped and dated. The bottles that need thought are the working solutions on a histology bench, because eosin is often held in alcohol, which adds flammability to the liquid. Keep those away from heat and ignition sources, and away from any oxidiser, even though the powder has no such restriction. Make sure the staining line reservoir is not topped up from a mixed bottle with another reagent, because the label then no longer describes the contents. A tray under bottles of 1% solution makes drips obvious, since the pink-red colour spreads quickly on white shelving and a paper label.

A clear, evenly coloured solution is what normal looks like. With age a precipitate forms, seen as a dark sediment on the bottom, flecks floating in the liquid or a crust round the neck and cap thread where the solution has dried. A bottle that has lost level, or whose lid has dried to a pink crust, has been losing solvent through the seal. The powder shows fewer signs, but caking or a damp, clumped look means moisture has entered, and pink dust on the cap points to a poor closure. Treat a bottle with a heavy sediment, a loose or glued lid or an unreadable label as stock to be listed rather than topped up and reused.

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.

Group eosin by form: powder in its original jar, and solutions by strength and by whether they are alcohol based, because that affects how they are packed with other items in a lab pack. The code that fits a school, college or university store is 16 05 06*, while human pathology and histology services clearing stock may use 18 01 06*. Note any heavy sediment or crusted lids on the request, since the carrier needs to know a closure may not hold. Pouring leftovers down a sink is not allowed, and a rinse of a pink bottle does not make it fit for general waste.

Usually held as: solid, 1% solution.

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.