Accepted answer
room temperature is above the refrigerated band, and how far above is the whole answer. Room temperature is not a number, so take the pharmacopoeial 20–25 °C and its 22.5 °C midpoint: 17.5 kelvin above the 5 °C middle of a 2–8 °C refrigerator. The ten-degree rule of thumb — degradation rate roughly doubling per 10 K — puts that at about 3.4 times the refrigerated rate. It is an order-of-magnitude statement about a rate, not a shelf life, and the top of the 20–25 °C band runs about 1.4 times faster than the bottom of it. Lyophilised material tolerates this far better than solution does, which is why it is shipped that way, but "tolerates" is a statement about weeks and the vial is being asked about months. Log the excursion rather than guess at it. Nothing here is medical advice, and research-use-only material is not approved for human use.
The relevant practical failure is not chemical at all: it is losing the link between a vial and its certificate when the box gets thrown away.
Keep vials in their original carton or in an opaque box. Light exposure matters for tryptophan-containing sequences and for anything with a chromophore, and a closed box is free.
Stated carefully, reconstituted with a preservative-containing diluent: refrigerated, conventionally treated as usable for about 28 days from first entry. Without a preservative, single use and discard.
Two-to-eight-degree refrigeration and minus-twenty freezing are the standard storage conditions for lyophilised peptides in supplier documentation across the market.
Dry, cold, dark, still. Four words and you have the answer.
The desiccant point is under-appreciated and costs nothing to act on. – lukas_sedlacek 8 months ago 8Adding for future readers: the domestic leg after delivery is the part you control. – plate_count_9k 6 months ago add a comment