Accepted answer
Probably not at minus 80 °C specifically, because that is not where stability programmes take their readings. Accelerated work is conventionally run at 25 °C and 40 °C, with the refrigerated condition as the control, so minus 80 °C sits between or beyond the published points and what you will find is bracketing rather than a measurement. minus 80 °C is 85 kelvin below a refrigerator, and below the glass transition of a lyophilised cake the ten-degree rule of thumb stops applying at all — solid-state chemistry is not slow liquid chemistry, it is a different regime, and the failure modes that survive it are mechanical rather than chemical. Whatever you find, check what was measured before you use it: a paper reporting purity at minus 80 °C has not measured content, and the two fail at different rates for different reasons.
Aggregation is a physical process and is the one most often caused by handling rather than by time.
Adsorption onto glass and plastic is significant at low concentrations — micrograms per millilitre — and negligible at milligrams per millilitre. It is the usual explanation for an apparent loss in a dilute preparation.
Reported and extrapolated stability by condition
| State | Condition | Usable window | Basis |
|---|
| Lyophilised solid | −20 °C, sealed, dry | 24–36 months | Supplier guidance |
| Lyophilised solid | 2–8 °C, sealed | 12–24 months | Supplier guidance |
| Lyophilised solid | 25 °C, sealed | 4–8 weeks | Extrapolated (Arrhenius) |
| Lyophilised solid | 40 °C, sealed | 1–2 weeks | Extrapolated |
| Solution, preserved | 2–8 °C | 28 days | USP microbiological convention |
| Solution, preserved | 25 °C | 3–7 days | Extrapolated |
| Solution, unpreserved | 2–8 °C | 24 hours | USP microbiological convention |
Windows for the solid state are chemical; windows for solution are microbiological and usually shorter than the chemical limit.
A mass spectrum resolves most of this: minus eighteen is dehydration or succinimide, plus one is deamidation, plus sixteen is oxidation, and an unchanged mass with a shifted retention time is an isomer.
Metal-catalysed oxidation of methionine is documented across peptide and protein formulations and is why chelators appear in some formulations.
Nothing here is medical advice, and research-use compounds are not approved for human use.
Sequence decides which pathways are even available. Check the residues.
edited 19 Jul 2025 by Dr_Otto_Lindqvist — updated for the 2026 guidance change
5Worth adding that residual moisture predicts this better than any printed date. – Dr_Hanne_Solberg 6 months ago 4I have kept vials both ways for a year and this matches what I saw. – tenth_of_a_unit 4 months ago add a comment