Cold-chain handling: from delivery to vial

What to do when a compound shipment arrives — and what counts as a thermal excursion bad enough to compromise the lot. Most research compounds 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:

1. Open the package. Do this even if you don't need the compound today — verifying lot integrity is time-sensitive.
2. 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.
3. 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).
4. Match lot numbers. Verify each vial's lot number against the packing slip and the COA.
5. 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 compounds are remarkably tolerant of brief temperature exposure — that's the whole point of freeze-drying. But "brief" has limits:

Exposure	Impact on lyophilized compound
Up to 7 days at room temperature	Minimal — most compounds 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 compounds 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 compounds 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 compounds 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 compound 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 compound 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 compound-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.