How to Read a Certificate of Analysis
What each section of a CoA means, and what to check before relying on one.
For Research Use Only
These products are intended for laboratory research use only and are not for human consumption. Not for use in food, drug, household, or cosmetic applications. All research should be conducted in accordance with applicable safety guidelines and regulations.
What a CoA Is — and Isn't
A Certificate of Analysis is the quality-control document issued for a specific production lot. It records what the issuing laboratory measured — typically identity, purity, and physical characteristics — for that batch, on that date.
The CoAs we share are the manufacturer's documents, provided on request when available for your specific lot. A manufacturer CoA is not the same as independent third-party testing, which we are working toward — see our Quality Standards for what we provide today.
The Sections, One by One
1. Product Identity
Product name, catalog or batch number, CAS number where assigned, and the lot number. The lot number is the anchor: every measurement on the document applies to that production run only. A CoA whose lot doesn't match the vial in hand tells you nothing about that vial.
2. Purity (HPLC)
High-performance liquid chromatography separates the sample into components and reports the target peptide's peak as a percentage of the detected chromatographic signal. "99%+" means impurities the method detects account for under 1% of the chromatogram — it is a method-limited number, not a census of everything in the vial: contaminants that co-elute with the main peak, respond weakly to the detector, or fall outside the method are not captured. Things to look at:
- • The stated purity percentage and the method (usually RP-HPLC, UV detection).
- • Whether a chromatogram image is included — a single dominant peak supports the number.
- • Purity is a proportion of detected signal, not a quantity: it does not state the total peptide content of the vial.
3. Identity (Mass Spectrometry)
Mass spectrometry measures the molecular mass of the material and compares it to the expected molecular weight of the peptide (listed on our product pages under Specifications). An observed mass within instrument tolerance supports — but does not by itself prove — that the material is the stated compound: a wrong-sequence or isomeric peptide can share the same intact mass. Unambiguous identity relies on orthogonal evidence (e.g. sequencing or fragmentation data). Read HPLC and MS together, and treat them as supporting a conclusion rather than settling it.
4. Appearance & Physical Data
Description of the lyophilized material (typically a white to off-white powder), sometimes with solubility notes or water content. A vial that looks materially different from the described appearance is worth a question before use.
5. Dates & Signatures
Analysis date, sometimes a retest or expiry date, and the issuing laboratory's sign-off. An analysis date long before the product's expected shelf life window is normal — the document describes the lot at release.
A 30-Second Checklist
- Lot number on the CoA matches the lot on your vial label.
- Product name and CAS (where assigned) match the product page.
- HPLC purity (of detected signal) meets the stated specification (99%+ for our peptides).
- MS observed mass agrees with the expected molecular weight.
- Issuing laboratory and analysis date are present.
Requesting a CoA
Email [email protected] with the product name — before purchasing is fine — and we'll share the manufacturer's documentation when available. If you've already ordered, include your order number and the lot number printed on your vial so the document matches your specific lot. Unfamiliar terms? See the Research Glossary.