Impurity
Also known as: impurities · related substances · truncated sequence
Anything in a sample that is not the intended peptide — truncated sequences, by-products, salts or solvents.
An impurity is any component of a sample that is not the target compound: incomplete or truncated sequences left over from synthesis, chemical by-products, residual solvents, or excess counter-ion salt.
Purity is essentially "100% minus the impurities", measured by HPLC. Because impurities can confound research, characterising them — not just the main peak — is part of a thorough Certificate of Analysis.
RELATED TERMS
Purity
The percentage of a sample that is the intended peptide, as measured by HPLC — the headline quality figure.
HPLC
High-Performance Liquid Chromatography — the standard technique for measuring the purity of a peptide.
Acetate Salt
The salt form peptides are supplied as; net peptide content is slightly below the raw weight because of the counter-ion.
Certificate of Analysis (CoA)
A batch-specific lab document reporting a compound’s identity and purity — the primary proof of what is in the vial.
Degradation
The breakdown of a peptide into inactive fragments — by hydrolysis, oxidation or enzymes — reducing purity and potency.
Educational content, not medical advice. All products supplied for research purposes only — not for human consumption.