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Chemical collection and stock control for UK schools, universities and hospitals

Trisodium citrate (CAS 68-04-2): storage and disposal

Clinics, pathology labs and histology stores keep trisodium citrate as 3.2% anticoagulant solution, while schools, colleges and universities hold the dihydrate crystals. It is not normally classified as hazardous, but it is still chemical waste. Citrate solutions are the item that goes wrong on a shelf, since a made-up bottle has no preservative to protect it.

CAS number
68-04-2
Form
Solid
Storage class
General
Usual EWC code, laboratory stock
16 05 09

What to do this week

  1. Without moving anything that looks damaged, check the label is readable and write down the opened date if it is not already there.
  2. Check it is stored as general stock, and apart from anything listed under "Do not store with" on this page. If nothing is listed, that does not prove it is safe with everything.
  3. If you no longer need it, add it to your disposal list so it can be included in a collection.

Safe storage in a school or lab

One practical check at the shelf is whether the label says solid or solution, and the concentration. Dihydrate crystals go in a dry, labelled, well organised store with a date on arrival and apart from food grade supplies. The 3.2% anticoagulant, whether in bottles or in blood collection tubes, belongs with clinical supplies and not among reagents, with a note of the date it was made or received. A clinic cupboard should keep the tubes away from patient-facing consumables. No particular chemical partners need separating, and the main task is labelling.

How to tell it has deteriorated

Solution is where change shows. A bottle or tube of anticoagulant that has become cloudy, grown a film or developed a smell has been contaminated, and should not be used. Crystals of the dihydrate show few visible signs, though caking or damp lumps mean moisture has entered the tub. Faded labels, a missing concentration and an unknown date matter most for both forms. Expired anticoagulant tubes that have lost their vacuum or have leaked are described as they are. A tub topped up from another container counts as mixed stock.

How it is disposed of

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 We do not publish a drain or general waste route for any chemical.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 non-regulated or low hazard laboratory pack with compatible chemicals.

The solid and the 3.2% solution are two different items on a collection request, so list them separately. It is not normally classified as hazardous, but it is still a chemical waste, so it must not go into a sink, drain, bin or sharps container. Healthcare holders such as clinics and pathology labs normally use the healthcare entry, and educational stores the laboratory chemical entry, though the producer classifies the waste. Record the container size, the stated concentration and the label condition. The carrier groups it with other low hazard stock.

Waste codes for Trisodium citrate
Usual EWC code, laboratory stock16 05 09
Human healthcare setting18 01 07
Usually classed as hazardous wasteNo

The code depends on where the waste came from and what it contains, and classifying it is the producer's duty. Use the waste code finder to see why.

Common quantities

Usually held as: dihydrate, 3.2% anticoagulant.

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.

Where it is commonly held

Questions

Can expired anticoagulant tubes go in clinical waste?

Unused, expired anticoagulant tubes containing citrate solution can be listed for specialist chemical waste collection. Tubes that have been used or contain blood require classification according to their actual contents and contamination. Record whether the tubes are unused or used, and describe the citrate solution as 3.2%.

Is the dihydrate solid handled differently from the solution?

They are listed as separate items. The solid is a dry chemical in a lab pack, and the solution is a liquid. Neither goes into a drain, whatever its classification.

How do we know if a citrate bottle has gone off?

A cloudy bottle, a film on the surface, an odd smell or an unreadable label are the signs. Stop using it, keep it closed and labelled, and arrange collection with the concentration noted.

Guidance only. Check your own risk assessment and your supplier's safety data sheet.

Hazard data source: PubChem GHS Classification, retrieved 31 Oct 2026. Formula C6H5Na3O7. EC number 200-675-3.

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