Certificate terms
How is HPLC purity calculated on a peptide COA?
Short answer
On Clean Peptide's ILS Laboratories certificates, HPLC purity is the target peptide's peak area as a percentage of all peptide-related peaks, measured by reversed-phase HPLC at 214 nm. ILS calls this area normalization and notes that non-peptide process-related impurities, if detected, are excluded from the calculation. It is a ratio of peaks, not an amount.
How each laboratory describes its purity figure
| Laboratory | How the certificate describes purity | Detector shown | Lots |
|---|---|---|---|
| ILS Laboratories | RP-HPLC area normalization at 214 nm; target peptide relative to all peptide-related peaks | UV 214 nm chromatogram | 24 lots |
| HYTE Research Division | Purity by HPLC-DAD; "peak area purity" on the KPV certificate | DAD signal at 214 nm on the Selank Spray chromatogram | GLP-2 Tirz 20 mg, KPV 10 mg, Selank Spray 20 mL |
| Accurate Test Labs | A purity figure with its chromatogram; no calculation note | PDA at 220 nm on the BPC-157 20 mg chromatogram | BPC-157 20 mg, GLP-2 Tirz 30 mg |
Read from the live lot pages on 30 October 2026. Wording from the certificate images and, for ILS, its portal notes. Epithalon 10 mg also reports a purity figure; its lot page names no laboratory or method.
A worked example: the TB-500 10 mg lot ACE-7203111 reads 99.72%, so the TB-500 peak made up 99.72% of the peptide-related peak area at 214 nm, against a specification of at least 95.0%. The same certificate measures 10.31mg of net peptide content; that is how much TB-500 is in the vial, which purity cannot tell you.
ILS also notes that purity values are capped at 99.9% to reflect the instrument's limit of detection, and that trace impurities below that threshold may be present. The 214 nm wavelength is in the ultraviolet, where the peptide bond absorbs, so peptide-related peaks show up there.
Where to verify
Follow-up questions
Does 99% purity mean the vial is 99% peptide by weight?
No. Purity compares peaks on the chromatogram. The weight of peptide in the vial is the separate net peptide content figure, given in mg.
All answersSold for laboratory research use only. Not for human or veterinary use.
