What to Look for in Lyophilized Peptides

Lyophilization is freeze-drying: the peptide solution is frozen, then placed under vacuum so the water leaves as vapour, leaving a dry powder. Most of the chemical reactions that degrade a peptide, such as hydrolysis and deamidation, need water, so the dry powder keeps far longer than the same peptide in solution. The exact shelf life depends on the compound and the formulation, and for most research peptides it has not been published.

A sound vial holds a uniform white or off-white powder, often as a solid cake or fluffy mass, in a sealed vial with a batch number on the label. After reconstitution the solution is clear and colourless with no visible particles. None of these checks shows identity or purity. Only a laboratory report for that batch, naming the laboratory, what the test covers and what it does not, with a verification key, speaks to what is in the vial.