Handling, Storage & Cold Chain

All material below describes laboratory handling and analytical practice for reference compounds supplied strictly for in-vitro research. Nothing here is guidance for human or animal use.

A reference standard is only a standard while it remains chemically what the certificate says it is. Peptides degrade by a small number of predictable routes: hydrolysis of the peptide backbone, oxidation of methionine and cysteine residues, deamidation of asparagine and glutamine, and aggregation into species the assay no longer resolves. Every one of those routes is accelerated by water, heat, light, and oxygen.

This is why storage is not housekeeping — it is part of the experiment. A lab that stores identically-sourced material two different ways will eventually publish two different numbers and blame the compound.

In the freeze-dried state, the dominant protective factor is the absence of free water. Keep the vial sealed until the moment of use; the stopper is the barrier, and every puncture is a small permanent change to the vial's internal environment.

Once in solution the molecule is mobile and every degradation route opens at once. Solution-state material is a consumable, not an archive.

Refrigerate immediately after preparation, keep it shielded from light, and record the reconstitution date on the vial itself rather than in a notebook that lives elsewhere. Where a protocol requires longer solution-state storage, aliquot into single-use volumes first: one freeze–thaw cycle across ten aliquots is far gentler than ten cycles on one vial.

The failure mode in most labs is not ignorance, it is drift. Write the storage conditions into the assay SOP rather than the storeroom procedure, log freezer temperature continuously rather than by spot check, and treat any excursion as a documented event with a decision attached — either the material is re-qualified or it is retired.