Mercury(II) chloride (CAS 7487-94-7): storage and disposal

Acids and oxidisers have no place beside mercuric chloride: toxic stock is kept apart from both so that a spill or reaction cannot release toxic fumes. A locked cabinet with a stock record suits the solid, away from food and drink areas and out of direct light. On a histology bench the same salt may be sitting in a working fixative, which may be less hazardous than the pure solid but is never safe, and some mercury fixatives also contain chromium(VI) compounds or formaldehyde, so it deserves the same locked store and a tray to catch a leak. Solutions of this salt attack many metals, so a metal shelf, cap or instrument tray near a fixative bottle is a poor arrangement. Older school bottles may carry the name corrosive sublimate, and they belong in the same cabinet under a legible modern label.

Start with the cap and the label. A histology bottle may be a reused container with a handwritten fixative name and no mention of mercury, and that gap is often the most serious fault on it. Corroded metal closures and a white crust of dried salt around the neck both suggest a leak or evaporation, and a crust is still the toxic salt. The white solid itself shows little change with age, although light can slowly darken mercury salts, so a grey or darker surface on old stock is worth recording. It should not be read as the hazard fading. Staining around the cap, a failed seal or a missing entry in the stock record are further reasons to report the bottle and leave it closed.

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 We do not publish a drain or general waste route for any chemical.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

Record the exact wording on the container before asking for a collection, including older names such as mercuric chloride or corrosive sublimate. Note whether it is a dry solid or a fixative solution, the container size and material, how full it is and any crust or corrosion around the closure. Those details decide how it is grouped, since this corrosive mercury salt needs a place apart from acids and oxidisers in the lab pack. The usual code depends on setting: 18 01 06* for human healthcare, otherwise 16 05 06* in a lab pack or 16 05 07* outside one, though the producer classifies the waste. Specialist collection is the only route, so it never goes into a sink, drain, general waste bin or skip, and nobody should try to treat it first. The consignment paperwork then stays on your file.

Usually held as: legacy stock, histology fixatives.

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.