Cold-chain handling: from delivery to vial
What to do when a peptide shipment arrives — verifying ice-pack temperature, transferring vials to long-term storage, and what counts as a stability-compromising thermal excursion.
What to do when a peptide shipment arrives — and what counts as a thermal excursion bad enough to compromise the lot. Most research peptides ship with refrigerated cold packs, but the "what now?" between delivery and benchwork is where stability is most often lost.
The 15-minute checklist
Within 15 minutes of taking delivery:
- Open the package. Do this even if you don't need the peptide today — verifying lot integrity is time-sensitive.
- Touch the ice pack. It should still be partially frozen or, at worst, cold-to-the-touch. A fully melted, room-temperature ice pack means the cold chain may have been compromised.
- Inspect the vials. Look for: physical damage to the glass, broken seals, displaced rubber stoppers, or visible moisture inside the vial. Lyophilized cake should be intact (not collapsed or melted into a film).
- Match lot numbers. Verify each vial's lot number against the packing slip and the COA.
- Move to long-term storage. Transfer the vials to your -20 °C freezer (or refrigerator, depending on the compound) within the 15-minute window.
What counts as a thermal excursion
Lyophilized peptides are remarkably tolerant of brief temperature exposure — that's the whole point of freeze-drying. But "brief" has limits:
| Exposure | Impact on lyophilized peptide |
|---|---|
| Up to 7 days at room temperature | Minimal — most peptides remain within spec |
| 14 days at room temperature | Acceptable for most; verify with COA stability data |
| Brief exposure to direct sunlight | Light-sensitive compounds (NAD+, etc.) compromised in hours; most peptides tolerate |
| Temperature > 40 °C for any duration | Risk zone. Stability data typically isn't validated above this. |
| Freezing of a reconstituted vial | Acceptable once; avoid freeze-thaw cycles |
| Repeated freeze-thaw (3+ cycles) | Measurable degradation. Aliquot to prevent. |
Reconstituted peptides are far more thermally fragile. Once dissolved, the typical window is 30 days at 2–8 °C (refrigerated) — extended time at room temperature accelerates degradation significantly.
What to do if cold-chain was lost
If you receive a package where the ice pack is completely warm and the cardboard insulator feels at ambient temperature:
- Don't immediately discard the lot. Lyophilized peptides usually tolerate days of room-temperature exposure. The lot may be fine.
- Photograph the package state. Include the ice pack and any thermal indicators (if shipped).
- Email Merit (info@meritpeptides.com) with the lot number and photos. We'll review the carrier's transit time + temperature record.
- Hold the lot from research use until we confirm or replace. Merit absorbs the cost of cold-chain failures we caused or that exceeded the validated stability window.
Long-term storage
Once the vials reach your facility:
- Lyophilized vials: -20 °C freezer, light-protected (a foil-lined box works), sealed in original packaging. Storage life ≥24 months for most compounds.
- Reconstituted vials: 2–8 °C refrigerator (a dedicated peptide fridge is ideal — avoid sample-rich biology fridges where contamination risk is higher).
- Aliquoted tubes: -20 °C for short term, -80 °C for long-term. Use cryotube racks to prevent tube-to-tube freezing damage.
Freezer placement matters
Don't store peptide vials in the freezer door. Door storage sees the greatest temperature fluctuation every time the freezer is opened. Put them deep in the freezer body. Better: a dedicated drawer or sealed cryobox that won't get rearranged.
For research use only. Cold-chain handling reflects standard peptide-handling literature and is not a recommendation for any specific study design. Always verify storage conditions against the COA's stated stability data for your compound.
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