Peptide Storage Guide

Sealed lyophilised peptide is stable for 24+ months at -20°C. Many compounds are stable for several months at 2–8°C. Avoid moisture: do not open the vial outside controlled humidity, and keep the rubber stopper intact.

Once dissolved in bacteriostatic water, most peptides remain stable at 2–8 °C for about 2 months. GLP-1 analogues and shorter peptides skew toward the longer end; very labile peptides toward the shorter end. Keep them upright, in the dark.

Avoid repeated freeze/thaw on reconstituted solutions. If you must freeze, aliquot first so you can thaw only what you need.

Four factors degrade peptide powder, and they are not equally important. Moisture is first by a wide margin: hygroscopic sequences absorb atmospheric water, which both adds mass and accelerates the reactions that break peptide bonds. Temperature is second, roughly doubling most degradation rates with every 10°C. Light — particularly UV — matters for sequences with sensitive residues. Oxygen matters least for most, but is not zero for sequences with oxidisable side chains.

The ranking has a practical consequence: what happens in the first minutes after a vial is opened often matters more than the following weeks of correct refrigeration. Working quickly, minimising headspace exposure and resealing promptly protects the material more than any freezer setting later.

Long-term archival storage — sealed, desiccated, −20°C or colder — keeps lyophilised material stable for years. The freezer is for the powder you are not using this month; the bench fridge is for the vial in active use.

A storage routine fails when it is too complicated to follow at the end of a long day. The workable version is short: log every vial in and out (batch number, opening date), keep unopened vials in the main freezer in a sealed container with desiccant, keep the active vial in the fridge door where it is visible, and never return a reconstituted aliquot to the powder vial.

Labelling does the quiet work: a vial without its batch number visible is a vial whose certificate you can no longer tie to it. Masking tape over the cap with the batch and opening date survives freezer cycles better than adhesive labels, and takes seconds to write.