Accepted answer
Answer first: for a lyophilised solid, transit temperature matters far less than people assume, and transit duration matters mainly because of what it does to the cold pack rather than to the peptide.
Reported ranges from Chinese origins to western Europe cluster around nine to fourteen days with tracking, with inland origins adding a domestic leg and coastal ones sometimes beating the range.
The part that matters: 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 twelve-day lane the material is at ambient for most of the journey regardless of what was packed.
Solid-state stability of lyophilised peptides at ambient is well documented in formulation studies, with residual moisture as the dominant variable.
Buy a data logger if the temperature history genuinely matters to you.
edited 1 Jul 2025 by marta_okonkwo — fixed an arithmetic slip in the third paragraph
6Minor: a tracking number going dark for a week is not the same thing as a parcel that has stopped. – tandem_gradient 8 months ago 5Confirming that a parcel sitting at a facility for six days moved the moment the paperwork was queried and answered. – n_takahashi 6 months ago add a comment