Every serious peptide supplier will tell you their material is "tested" and "99% pure." The Certificate of Analysis — the COA — is where that claim either holds up or falls apart. It is the lot-specific document that reports what a sample actually is and how pure it actually was, as measured by named analytical methods. This article is an educational guide to reading one: what each field means, which fields carry real weight, and the red flags that separate a genuine COA from a decorative one. It is not a dosing guide and not a treatment protocol. Cerberus Research Labs supplies peptides strictly for laboratory research use — not for human or veterinary use.
What a COA is, and what it is not
A Certificate of Analysis is a testing record tied to a specific lot or batch of material. It answers two questions: is this the compound it claims to be (identity), and how much of the sample is that compound versus impurities (purity). A COA is not a safety document, not an approval, and not evidence of anything beyond the sample that was tested. A COA that cannot be traced back to the exact lot in your vial is a marketing asset, not an analytical one.
Purity: the HPLC number, and how to read it
The purity figure on almost every peptide COA comes from HPLC — high-performance liquid chromatography. HPLC separates the components of a sample as they pass through a column, and a detector records each component as a peak. The "purity" percentage is the area of the main peak (your target peptide) expressed as a fraction of the total area of all peaks. A reported 99% means the target compound accounts for 99% of the detected material by peak area, with the remaining 1% being related impurities, synthesis byproducts, or residual reagents.
Two things matter more than the headline number. First, the chromatogram should be shown, not just the percentage — a single dominant, symmetrical peak with a flat baseline is what high purity looks like, and a real COA lets you see it. Second, the method should be stated: the column, the mobile phase gradient, and the detection wavelength. A purity figure with no chromatogram and no method is a claim, not a measurement.
Identity: mass spectrometry confirms what the molecule is
HPLC tells you how pure the sample is; it does not, on its own, prove the peak is the right molecule. That is the job of mass spectrometry (MS). MS measures the molecular weight of the compound and compares it to the theoretical weight of the target peptide's sequence. When the observed mass matches the expected mass, that is strong confirmation of identity. A thorough COA reports both the expected and observed molecular weight, and often includes the MS trace. A COA that reports a purity percentage but never confirms identity by mass is only telling you half the story — you know the sample is pure something, but not that it is the peptide on the label.
The fields that quietly matter
- Lot / batch number: the anchor of the whole document. It should match the number printed on the physical vial. No lot number, or a lot number that does not match the vial, breaks the chain of custody entirely.
- The testing party: a COA is far stronger when the analysis is attributed to a named third-party laboratory rather than an anonymous "in-house" line. Third-party attribution means an independent lab put its name on the result.
- Test date and method references: a real analytical result is dated and cites its methods. Undated results, or results with no method at all, cannot be evaluated.
- Appearance and physical description: minor, but a COA that describes the physical sample (e.g., white lyophilized powder) is describing something that was actually examined.
- Sequence and CAS / molecular formula: confirms exactly which compound was tested, which matters for peptides whose names are easily confused.
Red flags: how a decorative COA gives itself away
Once you know what a real COA contains, the weak ones become obvious. Watch for:
- A purity percentage with no chromatogram. If you cannot see the peak, you are trusting a number typed into a template.
- No mass-spec identity confirmation. Purity without identity is incomplete.
- No lot number, or one that does not match the vial. A COA that cannot be tied to your specific material is generic.
- No named lab and no test date. "Tested" with no who and no when is not a test result.
- The same COA reused across every lot. Analytical results are lot-specific; a single static PDF served for all inventory is a tell.
- Rounded, suspiciously uniform numbers with no supporting trace. Real chromatography rarely produces the same tidy figure every time.
The uncomfortable truth of this market is that a convincing-looking COA is cheap to produce and almost never checked. The suppliers worth trusting are the ones that publish the parts you could actually verify — the chromatogram, the named lab, the lot-specific detail — not just the headline number.
How Cerberus documents its material
Cerberus Research Labs publishes per-lot documentation with named third-party HPLC testing, and makes the source available rather than asking you to take a percentage on faith. You can review the actual certificates in our public COA library, and every lot ships with its own lot-specific record. The reason we lead with this is simple: in a vertical where "99% pure" is printed on everything, the documentation you can inspect is the only claim that means anything. Our approach to identity and purity reporting is described further on the documentation page.
What a COA does not establish
A Certificate of Analysis reports identity and purity for a tested lot. It does not establish that a compound is safe, effective, or appropriate for any use, and it is not an endorsement of use. Cerberus Research Labs does not provide dosing guidance, does not make efficacy claims, and does not represent any compound as suitable for human or veterinary use. Every product referenced here — including Retatrutide, Tirzepatide, BPC-157, and Semax — is a research-use-only material.
The honest read
Reading a COA is a five-minute skill that saves researchers from a common failure mode: paying for documentation instead of testing. Check that the lot number matches the vial, that purity is backed by a visible chromatogram and a stated method, that identity is confirmed by mass spec, and that a named lab and a date stand behind it. When those pieces are present, you are looking at a real analytical record. When they are not, you are looking at a PDF. The full research catalog lists every compound with its lot documentation available for review before you buy.