Shipping Temperature and Cold Packs: What Matters for Lyophilised Peptides

Lyophilised peptides are shipped at ambient temperature by most suppliers, including us, and that surprises people who expect a cold pack. This guide explains why dry powder tolerates transit, when it does not, and what to check when a parcel arrives after a week in a hot vehicle.

Why the dry powder is the stable form

Nearly every degradation route a peptide can take — hydrolysis of the backbone, deamidation of asparagine and glutamine, oxidation of methionine and cysteine — needs water, or is greatly accelerated by it. Freeze-drying removes most of it. What remains is a solid with very little molecular mobility, in which those reactions run orders of magnitude more slowly than in solution.

That is why the meaningful temperature rule for lyophilised material is about cumulative heat over months, not about a few warm days in transit. Our guide on degradation pathways covers the chemistry.

What actually threatens a parcel

• Moisture, not heat. The real risk is a vial seal that lets humid air in. Once the powder picks up water, every reaction above becomes possible at ordinary temperatures.
• Repeated warm–cool cycling in a vehicle, which drives condensation inside packaging if any moisture is present.
• Physical damage. A cracked vial or a compromised stopper matters far more than the temperature the box reached.
• Light over long periods, for sequences containing tryptophan, tyrosine or cysteine.

Why cold packs are usually theatre

A gel pack keeps a parcel cool for one to two days. A domestic ground shipment takes three to seven business days. By day three the pack is at ambient temperature and has added nothing except, in some cases, condensation inside the box when the cold pack sweats. For lyophilised powder, dry ambient transit is generally the better of the two.

Cold chain genuinely matters for material already in solution, for certain unstable sequences, and for long-term storage. It is not what protects dry powder in the post.

What to check when a parcel arrives

1. Seals and stoppers. Intact, flat, not pushed in or lifted.
2. The cake. A normal lyophilised cake is a dry solid or fine powder, usually white. A collapsed, shrunken or glassy-looking cake, or material that has turned sticky, points to moisture ingress — this, not a warm box, is the sign worth acting on.
3. Colour. Marked discolouration against what the product page shows is worth querying.
4. Lot number against the certificate. See lot numbers and traceability.

If anything looks wrong, photograph it before opening anything further and contact the supplier.

After arrival

Store the sealed vials cold, dry and dark, and let each vial reach room temperature before opening it — opening a cold vial draws humid air onto cold powder, which is the one routine mistake that reliably causes damage. Our storage and handling guide covers the conditions, and solubility and solvent choice covers what happens next.

How we ship

From a US warehouse, by USPS, within the United States only, on the next business day after payment is confirmed. Typical transit is three to seven business days, at ambient temperature, with the lot number on each vial label matching the certificate published on the lab results page.

Materials supplied by BMS Labs are for laboratory research use only and are not for human or veterinary use.