How to read a peptide certificate of analysis
Every credible COA answers four questions in the same order. Learn the structure once and you can evaluate any supplier's documentation in a few minutes.
Research use only. Every compound referenced here is a laboratory reference material supplied to qualified researchers and institutional laboratories. None are medicines, supplements or consumer products, and none are for human consumption.
A certificate of analysis is a laboratory record, and like any record it can be complete, partial or decorative. The difference matters when material is going into a study that may later be reviewed.
This guide sets out the four questions a certificate should answer — identity, purity, quantity and traceability — and the specific fields that answer each one.
1. Identity: which peptide is this?
Identity is answered by mass spectrometry. The certificate should state the theoretical molecular mass and the mass the laboratory measured, along with the ionisation method. When the two agree, the material matches the intended structure, including any modifications such as a lipid side chain or a copper complex.
Purity data cannot substitute for this. A chromatographically clean peak belongs to whatever the sample actually is.
2. Purity: how much of it is the target?
Purity is answered by reverse-phase HPLC, reported as the main-peak area percentage at a stated wavelength, usually 214 nm. The certificate should also state the column, gradient and whether related substances were quantified separately.
A chromatogram should accompany the number. Reviewers look for a single symmetrical peak, a stable retention time and the absence of unintegrated shoulders.
3. Quantity: how much peptide is in the vial?
The label states peptide mass, while the vial contains lyophilized powder that includes counter-ions, buffer salts and residual moisture. A complete certificate reports peptide content so a laboratory can correct its concentration calculation.
Where peptide content is omitted, a mass-based dilution assumes the label equals the peptide, which overstates the delivered quantity.
4. Traceability: which batch was tested?
Traceability is answered by the lot code. It must match the vial label exactly, appear on the analysis record, and carry an analysis date and a testing-laboratory identification.
A certificate without a lot code is a datasheet about a product line, not a record of the material in your hands.
Third-party or in-house testing
An independent laboratory with no commercial interest in the result produces stronger evidence than an in-house bench reporting on its own production. It is reasonable to ask which laboratory performed the assay and whether the certificate names it.
The most useful certificates state the laboratory, the method and the date in enough detail that a reviewer could reproduce the analysis.
A quick review checklist
Run through these before accepting any batch:
- Lot code on the certificate matches the vial label
- Theoretical and measured mass both reported
- Purity percentage accompanied by method and chromatogram
- Peptide content stated separately from total fill weight
- Testing laboratory named, analysis date present
- Certificate covers one lot, not a product range
What a COA does not establish
A certificate of analysis is not a safety assessment, not a stability study and not a regulatory approval. It documents the analytical properties of a batch of research material.
In this catalog every compound is a laboratory reference material supplied to qualified researchers and institutions, for research use only, and not for human consumption.
BPC-157 10mg
$49.95
LOT · TERZ-30mgTirzepatide 30mg
$149.99
LOT · SEM-10mgSemaglutide 10mg
$69.99
Common questions
What is the difference between HPLC purity and peptide content?
Purity describes what proportion of the detected material is the target peptide. Peptide content describes how much of the powder's mass is peptide rather than salts and moisture.
Is mass spectrometry always required?
For unambiguous identity, yes. HPLC alone cannot distinguish between a pure target peptide and a pure sample of a different peptide.
How current should a COA be?
It should belong to the specific lot being supplied, with an analysis date for that lot. A certificate from an earlier campaign does not describe a newly produced batch.
Where can I find certificates for compounds in this catalog?
The public COA directory lists current lot certificates, and each compound page links to the certificate for its lot.