Unopened
- Store at 2 to 30 °C, dry and away from light, with the cap or bag tightly sealed.
- The expiry on the label and specification sheet applies to unopened containers stored correctly.
- Avoid refrigerator doors and other places where condensation forms; temperature swings do more harm than room temperature itself.
After opening
- Dehydrated media and peptones are hygroscopic. Reseal immediately after each use; split large packs into smaller portions or add a desiccant to the pack.
- Use within about six months of opening. If the powder is still free-flowing, the colour and odour are unchanged and the solution is clear, the product is normally still fit for use.
- Prepared broths and plates have their own shelf life: poured plates typically keep two to four weeks refrigerated, less when they contain antibiotics or dyes.
Signs of deterioration
- Hard caking or a clearly darker colour.
- Cloudiness or undissolved particles after preparation.
- pH outside specification after preparation.
- Reduced performance: control strains grow less well than before.
Do not use a deteriorated lot for routine testing. Switch to a fresh lot and keep a sample of the old one for investigation.