Is a QYB order from Chengdu likely to hold cold chain to Canada?

The specifics, since they change the answer: QYB · Chengdu · Canada.

I would like to define my thresholds before I have a result, for obvious reasons.

I want a plan with explicit stopping rules, not just steps.

How do I make this decision on evidence rather than on feel?

The short version: a spent cold pack on arrival is expected, the solid does not mind, and the pack was never going to last twelve days.

A single phase-change pack in a thin-walled box holds below ten degrees for roughly one to two days at twenty-five degrees ambient, and under a day at thirty-five. On a nine-to-fourteen-day lane the material is at ambient for most of the journey whatever was packed with it.

The part that matters: a pack that arrived hard tells you about the last day of transit only, since it will have melted and, if the ambient dropped, partially refrozen.

The caveat is that a warm transit is survivable for a solid and materially different for a solution.

Lyophilised tolerates the lane. That is the answer for almost every order.

Answering this needs the transit duration and the ambient temperature, and then the arithmetic is straightforward.

Arrhenius behaviour means the degradation rate roughly doubles per ten degrees. A week at thirty degrees is therefore a meaningful exposure for a solution and an immaterial one for a dry solid.

Mechanically, anything shipped in solution is a different risk category, because hydrolysis and deamidation proceed in the aqueous phase and are strongly temperature-dependent.

Phase-change pack hold time is a function of mass, latent heat and insulation, and published figures for small parcels are on the order of one to two days.

Solutions are a different question and deserve the worry the solids get.

The domestic leg after arrival is the part most often left in a warm hallway and least often worried about.

Once the parcel arrives, the domestic leg is the controllable part: get it into the refrigerator promptly rather than leaving it in a warm hallway for a day.

That is the argument for shipping lyophilised rather than for shipping colder. A dry powder with low residual moisture is stable at ambient for months; the pathways that matter need water.

Single-use temperature loggers are standard practice in supply chains where temperature genuinely matters and are inexpensive at parcel scale.

A cold pack tells you nothing about the eleven days before the last one.

Buy a logger if you actually want to know. Everything else is inference.

edited 13 Jul 2026 by ines_brandt — tightened the wording; no substantive change

The honest answer is that the cold pack is doing much less than people think and that shipping lyophilised is what actually protects the material.

A single-use temperature logger costs a few pounds, records the whole journey and converts an argument into a record. If the history matters, this is the answer.

Solid-state stability of lyophilised peptides at ambient temperature is documented in formulation studies with residual moisture as the dominant variable.

Nothing here is medical advice, and research-use compounds are not approved for human use.

A liquefied pack is expected. It is not evidence of a problem.

If temperature history matters to you, buy a data logger. It is the only way to know.

Asking a supplier to hold a shipment during a heatwave is reasonable and the better ones agree; the cost is a week and the benefit is a shorter warm exposure for anything in solution.

Arrhenius kinetics predict approximately a doubling of degradation rate per ten-degree rise and are the standard basis for cold-chain design.

The domestic leg is the part you control. Refrigerate it promptly.

edited 11 Jul 2026 by anja_hellstrom — reworded for clarity after a comment