How to read a peptide certificate of analysis
What each line on a COA means, from HPLC purity to peptide content, and what to check before you buy peptide powder.
Lot code and dates
A certificate of analysis belongs to one production lot. The lot code on the certificate should match the one on your pouch, with a manufacture date and an expiry date. A seller who shows one certificate for every batch is showing you a sample, not your powder.
| Product | Lot | HPLC purity | Certificate |
|---|---|---|---|
| GHK‑Cu | ZXP-T7QB | 99.57% | |
| AHK‑Cu | 9T2-ZHFP | 99.6% | |
| SNAP‑8 | MCB-DHR6 | 99.56% |
Look up any lot on the lab results page.
Purity (HPLC)
High-performance liquid chromatography separates the powder into its components. Purity is the main peak's share of the total, so 99.57% means everything else the column found adds up to 0.43%. Cosmetic peptide specifications start at 98 or 99%.
Identification
Purity says the powder is one thing. Identification says it's the right thing: the main peak comes out at the same time as a reference standard of that peptide.
Peptide content
Purity measures how clean the peptide is. Peptide content measures how much of the powder's weight is peptide; the rest is bound water and the counter-ions every peptide salt carries. Our GHK‑Cu lot is 70.8% GHK and 11.9% copper, and our SNAP‑8 lot is 87.4% peptide.
Water content and pH
Peptide powders pull moisture from the air, so a water limit shows the lot was dried and sealed properly. GHK‑Cu came in at 7.8% (limit ≤8.0%). The pH of a copper peptide solution should sit between 5 and 7; outside it, the copper starts to let go.
Residual solvents
Peptides are made and purified with solvents like acetonitrile and dichloromethane. The certificate should list them with limits. Neither was detected in our GHK‑Cu, and our SNAP‑8 measured 115 ppm acetonitrile against a 410 ppm limit.
Heavy metals and microbiology
Lead, arsenic, mercury and cadmium, each with a limit in ppm, plus counts for bacteria, yeast and mold. These matter most for powders you'll leave in a serum for weeks.
Red flags
No lot code. No specification next to each result. A purity figure without the method. The same PDF on every listing. Numbers that never change from batch to batch.
