Quality
How to Read a Certificate of Analysis (COA) for Research Peptides
· SupplyPeptides Research Hub
A Certificate of Analysis (COA) is the difference between “trusted supplier” marketing and verifiable material. For research peptides, a useful COA tells you what was tested, how, on which batch, and with what result — ideally matching the lot on your vial.
Fields that matter
- Product / compound name — must match the SKU you ordered.
- Batch or lot number — the join key between vial, COA, and your lab records.
- Purity method — usually HPLC; note the reported % and any chromatogram attachment.
- Identity method — mass spectrometry (MS) or equivalent strengthens confidence that the main peak is the named peptide.
- Appearance / form — e.g. white lyophilised powder.
- Test date and lab — third-party labs are a stronger signal than unsigned internal sheets when available.
What HPLC purity does (and does not) mean
HPLC purity is typically a relative peak-area estimate under defined conditions. A result of ≥99% is a strong purity signal, but it is not a guarantee of biological activity in your assay, nor proof that storage after shipping preserved the material. Pair HPLC with identity data and sensible cold-chain / storage practice.
Red flags
- COA “available on request” with no published PDF for the live lot.
- Lot number on the COA that does not match the vial.
- Purity claimed without method (no HPLC/MS stated).
- Human-use marketing on the same page as the COA — a compliance and credibility warning for institutional buyers.
How SupplyPeptides approaches COAs
We publish batch documentation on product pages where metafields are populated, and we maintain a searchable COA lookup library. If a lot is missing, contact us before you run critical experiments — do not proceed on trust alone.
Related reading
Frequently asked questions
What does HPLC ≥99% mean?
HPLC purity estimates the relative area of the main peak versus impurities under defined chromatographic conditions. It is one quality signal — identity confirmation (e.g. mass spectrometry) and batch matching still matter.
Where can I look up SupplyPeptides batch COAs?
Use the COA library at /coa and search by batch or lot number, or open the COA link on the relevant product page when published.