The three storage variables
Storage stability is governed by three factors: temperature, light, and humidity. Lower temperature slows degradation, light promotes oxidation, and humidity reintroduces the water that lyophilization removed.
- Temperature: store dry solid desiccated at −20°C to −80°C.
- Light: protect from direct light, especially for oxidation-sensitive residues.
- Humidity: keep vials sealed and desiccated until use.
Freeze-thaw and prepared material
Once a material is dissolved for an in vitro assay, its stability drops. Repeated freeze-thaw cycles of a prepared solution accelerate degradation, so prepared material should be aliquoted into single-use fractions before freezing.
Sequence-dependent stability
Stability is not uniform across peptides. Sequences containing oxidation-prone residues (such as methionine or tryptophan) degrade faster under light and oxygen, while others are limited mainly by hydrolysis. The COA and handling guidance for each material reflect these differences.
Labeling and logbook practice
Label every aliquot with the lot number and the date it was prepared, and log storage conditions. Consistent labeling is what makes a batch traceable months later.