Sodium perchlorate (CAS 7601-89-0): storage and disposal

In a university store it belongs in a dedicated oxidiser space, on non-combustible shelving, well clear of solvents, acids and alkalis. The hazard particular to this salt comes from its thirst. It takes up water from the air, and the resulting solution will wick into whatever sits beneath it: a cardboard box, a paper label, a wooden shelf. Once that dries, perchlorate is left in organic fibre, which is exactly the explosive mixture to avoid. So no cardboard packaging, no paper shelf liners and no lab roll under the jar. Shared research benches are where this tends to go wrong, with a jar left beside solvent bottles. If you find a damp jar on a wooden shelf, do not lift it. Say so in your enquiry.

Water uptake is the main change with age. Free flowing white crystals begin to clump, then look wet, and in a damp room can slump into a syrupy layer at the bottom of the jar. The salt itself shows no colour change, so it otherwise gives few visible signs. What to look for instead is the evidence around it: a white crust at the neck, a stained or softened label, marks on the shelf, and any paper fibres or dust inside the jar. Organic contamination is the real danger, and it may not be visible at all. If the jar is damp, crusted or of unknown history, do not open or move it, and get a specialist assessment before anyone tries to tidy up.

This does not go through our standard collection route. It is arranged by manual enquiry, and never goes down the drain or into general waste.

It leaves only after a manual enquiry, because this salt is not quoted online and the online quote path does not accept it. What cannot be judged from a form is whether it has met organic material, and that decides everything. A store assessment is recommended, with a competent chemist seeing it in person, and a warning sign may bring in an explosives or emergency specialist. For the enquiry, give the quantity, whether it looks damp, what it stands on, and whether it may have touched paper, solvent or wood. Do not open it, move it or try to make it safe beforehand. It must never go into a sink, a drain, a bin or a skip. University holdings normally take code 16 05 06*.

Usually held as: solid.

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.