Accepted answer
Whatever the refrigerated figure is, divide it by about 4. 25 °C is 20 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 — makes that about 4 times the refrigerated rate, which is an order-of-magnitude statement and not a shelf life. So a preparation with a twenty-eight day refrigerated figure has roughly 7 days at 25 °C on the same assumption — an order-of-magnitude answer, not a shelf life, and it says nothing about sterility, which has its own clock. "Within specification" also needs a specification: purity, content, or both, and at what limit. Without that the question has no numerical answer at all.
In practice, asparagine and glutamine are the deamidation risk, and methionine is the oxidation risk.
Light exposure matters for tryptophan-containing sequences and for anything with a chromophore. Amber vials and a closed box are free mitigations.
Hydrolysis cleaves the backbone, most readily at aspartate-proline and aspartate-glycine sequences, and is acid-catalysed. In a dry solid it barely proceeds at all.
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.
A mass spectrum names the pathway. Plus one, plus sixteen, minus eighteen.
7Adding for future readers: the domestic leg after delivery is the part you control. – halvard_ness 9 months ago 6I would add a sentence about light, since tryptophan-containing sequences care. – felix_araya 7 months ago add a comment