Process-related impurity - Glossary

Process-related impurity is a manufacturing byproduct that remains in a final peptide or research chemical after synthesis. These unintended materials are left over from production. Checking impurity levels in a lab report or Certificate of Analysis (CoA) helps judge manufacturing quality and product safety.

Main process-related impurity types and testing context

Process-related impurities include synthesis artifacts like truncated or deleted amino acid sequences, chemical residuals such as leftover solvents or scavengers, unwanted counter-ions like trifluoroacetate (TFA), and biological residues like host cell proteins or DNA. Identifying them helps verify a peptide's purity and composition.

Laboratories use Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS) to identify and quantify impurities by weighing each component and determining its molecular structure. Stability-indicating high-performance liquid chromatography (HPLC) helps distinguish impurities created during manufacturing from those that form later during storage, giving a clearer picture of the product's history.

Practical interpretation risks around process-related impurities

Do not assume process-related impurities are inert; they can carry toxicity, alter biological activity, or trigger immune responses.
Do not rely on a 98% purity claim without identifying the remaining 2%, as it may contain toxic impurities that a quality report should specify.
Do not treat high residual TFA or unrelated peptide contamination as minor, as it indicates poor purification and a failure to follow Good Manufacturing Practice (GMP).
Do not confuse process-related impurities with product-related degradants that form during storage due to time or temperature; a thorough lab report must distinguish both.

Main process-related impurity types and testing context

Practical interpretation risks around process-related impurities

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