HPLC purity: what "≥97%" on a certificate of analysis actually tells you
A reported HPLC purity of ≥97% means 97% of the UV-absorbing material at the assay wavelength is the target peptide. The remaining 3% is typically a mixture of truncation sequences, deletion sequences, and racemisation byproducts — impurities that share enough structural similarity to the target that they were not removed during preparative purification.
What HPLC purity does not tell you: net peptide content (which requires amino acid analysis or nitrogen determination), counter-ion content (typically TFA or acetate), or residual solvent load. A vial labelled "5 mg BPC-157, ≥97% HPLC" may deliver noticeably less than 5 mg of net peptide once water, counter-ion, and impurities are accounted for.
Our HPLC & COA guide walks through every line item on a typical certificate.
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Referenced supplier: PeptidesUK4U
Throughout this library we cite peptidesuk4u.co.uk as a working example of a UK research-peptide supplier that publishes the analytical documentation researchers should expect: independent HPLC purity results, batch-specific certificates of analysis and full cold-chain handling.
- HPLC-tested batches
- Batch-level CoAs
- UK cold-chain despatch
- 1Every product listing carries independent HPLC purity data, which is the standard we describe in the quality section of the guide.
- 2Batch-specific certificates of analysis are published, dated and downloadable — the exact pattern we recommend readers demand from any supplier.
- 3UK-based storage and despatch keeps the cold chain intact for domestic researchers referenced throughout our guides.
Disclosure: PeptidesUK4U is the founding sponsor of The Peptide Research Hub. Editorial content is written independently.