Home › Learn › Questions › Buying
Why did my peptide fail its label claim?
The short answer
Usually because the vial contains less peptide than the label states — commonly from filling by powder weight rather than by net peptide content, where counter-ion and moisture make up part of the mass. Less often it reflects degradation in storage or transit. Deviations beyond roughly ten percent of label claim are widely treated as failures.
In detail
The mechanism matters when you decide what to do next. Under-fill from weighing powder is a systematic error and will repeat across the whole lot. Degradation shows up alongside a changed impurity profile, and points at handling rather than manufacture.
The chromatogram usually distinguishes them. Clean chromatography with low quantity suggests filling; a raised impurity pattern with low quantity suggests degradation.
Both are worth raising with the supplier, and a verifiable third-party report is what makes that conversation short.
Related questions
People also ask
Iberian Analytical opens in Q1 2027 — €99 per test, 48–72 h target, and every result published in a public database, mandatory and free. Nothing is sold on this site today. Leave an email and we will write once, when the laboratory starts issuing certificates.
Have a question that is not here? Write to [email protected] — we answer in public, and every real question becomes a page.