Pep TrustWhat Should a Legitimate Peptide COA Include?
A Certificate of Analysis is a structured document, not a marketing graphic. Here is every field a real one should contain, why each matters, and exactly what it means when one is missing.
Most people evaluate a COA by vibe: it has a logo, a chart, and a big purity number, so it must be real. But a Certificate of Analysis is a technical report with an expected structure. Once you know which fields belong on it, a weak or forged document becomes obvious — usually because of what isn't there.
This is the field-by-field checklist. Work down it with a COA open beside you. If you want the conceptual background first — what a COA is and why third-party testing beats in-house — start with what is a Certificate of Analysis.
- Product and compound identification
- Batch traceability
- Testing laboratory information
- Dates
- Analytical methods
- Purity results (HPLC)
- Identity results (mass spectrometry)
- Net peptide content
- Scope testing, storage and sign-off
1. Product and compound identification
The document must state precisely which compound was tested — not just a trade name.
Fields to look for
- Product / peptide name, matching your vial label exactly
- Amino acid sequence (one- or three-letter code)
- Molecular formula
- Theoretical molecular weight, in daltons
- Appearance — typically "white to off-white lyophilized powder"
The theoretical molecular weight is the single most useful field on the page, because it's the value the mass spectrometry result must match. It's also the field forgers most often get wrong: if someone edits a template from one peptide into another, the stated weight frequently doesn't correspond to the named compound.
A named peptide with no sequence and no theoretical mass. Without them, nothing on the rest of the document can be checked against chemistry — you're being asked to take the purity number on faith.
2. Batch traceability
A COA describes one specific production run. That link is what makes it evidence about your vial rather than a general statement about the product line.
Fields to look for
- Batch or lot number — specific and unique
- Quantity / fill weight tested or produced
- Manufacturing or synthesis date where available
- Retest date (research peptides usually carry a retest date rather than a true expiry)
Then do the one check that costs you nothing: compare the lot number on the COA to the lot number printed on the vial or packing slip. If they don't match, the document may be describing material you never received.
Generic identifiers like "Batch 001," "LOT-A," or no lot number at all. These are the signature of a generic COA reused across many batches — one of the most common forms of documentation fraud.
3. Testing laboratory information
A COA is only as credible as the lab behind it, so the lab has to be identifiable and reachable.
Fields to look for
- Full laboratory name
- Physical address — a street address, not "California, USA"
- Contact details — phone, email, or both
- Accreditation status, ideally ISO/IEC 17025, with the accrediting body named (ANAB, A2LA, UKAS, CNAS)
- Accreditation certificate number, so the claim can be looked up
- Report or certificate number unique to this document
- Client name — who submitted the sample
The client-name field is quietly informative. It tells you whether the vendor actually commissioned the test, or whether the document was lifted from somewhere else entirely.
Laboratories are accredited under ISO/IEC 17025 — never "certified" or "approved." A COA advertising an "ISO 17025 certified lab" is using language a real accredited lab wouldn't. It's a small wording slip that often accompanies bigger problems.
4. Dates
Three dates matter, and they should form a sensible sequence: sample receipt date → analysis date → report issue date.
For active stock, testing within the last 12–18 months is the working expectation; beyond about 24 months, the document tells you little about material sitting in inventory today. Dates should also be specific. "Q4 2025" is not an analysis date.
Dates that don't line up — a report issued before the sample was received, an analysis date predating the company's existence, or a COA newer than the batch it claims to describe.
5. Analytical methods
Any real analytical report states how the numbers were produced. Method parameters are hard to fabricate convincingly and are frequently omitted from fakes.
For HPLC (purity)
- Column type — usually reverse-phase C18 for peptides
- Mobile phase — typically a water/acetonitrile gradient with TFA
- Flow rate — commonly 0.5–1.5 mL/min
- Detection wavelength — 214 nm or 220 nm for peptides
For mass spectrometry (identity)
- Instrument and ionization mode — MALDI-TOF, ESI-MS, or LC-MS
A purity percentage with no named method, or a chromatogram with no parameters anywhere on the page. That combination suggests the graphic is illustrative rather than a record of actual analytical work.
6. Purity results (HPLC)
This is the number everyone reads, and it should never appear alone.
Fields to look for
- Purity percentage with real decimal precision — 98.37%, not "99%"
- The specification it was judged against, e.g. "Spec: ≥98%"
- Pass / fail determination
- The chromatogram itself, with a sharp main peak, a stable baseline, and visible integration lines
A result without a specification is only half a result: the spec is what turns a number into a judgment. And the chromatogram is the underlying evidence — a purity figure with no chart is an assertion, not a measurement.
Suspiciously round or perfect values — exactly 99.0%, 99.9%, or 100% — and chromatograms with zero minor impurity peaks. Even genuinely high-purity peptides typically show trace impurities in the 0.1–1% range. Perfection is a manufacturing impossibility, not a selling point.
7. Identity results (mass spectrometry)
HPLC tells you how pure the sample is; it cannot tell you the sample is the right compound. A chromatogram can show 99% purity of the wrong peptide entirely. Only mass spectrometry closes that gap.
Fields to look for
- Theoretical mass (from the sequence) and observed mass (measured), shown side by side
- The mass spectrum itself
- Charge states where relevant — [M+H]⁺, [M+2H]²⁺, [M+3H]³⁺ — which should all resolve to the same molecular weight
The two masses should agree within instrument tolerance: roughly ±0.1–0.3 Da for MALDI-TOF on peptides under 2,000 Da, often tighter for ESI-MS. A small, realistic difference is a sign of genuine measurement.
No MS data at all — HPLC alone cannot verify identity — or an observed mass that matches theory exactly, to every decimal, with no error whatsoever. Real instruments have finite precision.
Run this checklist automatically
Pep Trust reads a COA and reports which of these fields are present, whether the molecular weight matches the named peptide, and whether the lab is traceable — with every gap explained in plain language.
Verify a COA — free8. Net peptide content
The most commonly missing field on an otherwise decent COA — and the one that most affects how much peptide you actually have.
Purity is the share of peptide material that's the correct sequence. Net peptide content (NPC) is the share of the total powder weight that is peptide at all, rather than counterions (TFA or acetate), bound water, and residual solvents. NPC commonly runs 60–90%.
The two are independent. A vial can be 99% pure and still only ~72% peptide by weight — meaning a "10 mg" vial holds roughly 7.2 mg of actual peptide. If a COA reports NPC, it should also name the method used: amino acid analysis (AAA), elemental analysis, or UV spectrophotometry.
A missing NPC figure is a completeness gap, not evidence of fraud — plenty of legitimate COAs omit it. But without it you cannot calculate how much peptide you're actually working with. See purity vs net peptide content for the full breakdown.
9. Scope testing, storage and sign-off
The final block covers everything beyond identity and purity.
Extended testing (tiering upward in rigor)
- Residual solvents
- Heavy metals
- Water content (Karl Fischer)
- Microbial / bacterial endotoxin testing
Document sign-off
- Storage and handling conditions — e.g. store lyophilized at –20°C, protect from light
- Analyst name and signature, or lab-director certification
- Verification route where offered — a QR code or report-lookup URL on the lab's own domain
Extended testing is a genuine quality signal but is not standard on every research-grade COA. Its absence lowers completeness; it doesn't by itself suggest a fake.
The one-page checklist
Not every field carries equal weight. This is how to triage what you find:
| Field | Tier | If missing |
|---|---|---|
| Product name + sequence + theoretical MW | Mandatory | Nothing can be verified — walk away |
| Specific batch / lot number | Mandatory | Document isn't tied to your vial |
| Laboratory name, address, contact | Mandatory | Unverifiable source — treat as no COA |
| Analysis date (recent, specific) | Mandatory | May not describe current stock |
| Purity % with specification | Mandatory | A number with no standard behind it |
| HPLC chromatogram | Mandatory | Result asserted, not evidenced |
| MS data: theoretical vs observed mass | Mandatory | Identity unconfirmed — could be any compound |
| Stated method parameters | Strong signal | Suggests illustrative, not real, data |
| ISO/IEC 17025 accreditation + number | Strong signal | Requires extra due diligence on the lab |
| Analyst name / signature | Strong signal | No one is accountable for the result |
| Net peptide content + method | Strong signal | Can't calculate actual peptide mass |
| Client / submitter name | Nice to have | Chain of custody less clear |
| Contaminant / endotoxin testing | Nice to have | Narrower testing scope |
| Storage conditions | Nice to have | Minor completeness gap |
| QR / online verification | Nice to have | Verification requires contacting the lab |
The practical rule: a missing mandatory field is disqualifying on its own. Missing "strong signal" fields are cumulative — one is a question, three or more is a pattern. Missing "nice to have" fields describe a thinner COA, not a dishonest one.
What a complete COA still doesn't certify
Even a COA that passes every item above has limits worth holding onto:
- It isn't a safety assessment. Purity is not safety and not potency.
- It describes the sample that was tested — not necessarily the vial in your hand.
- It says nothing about handling after testing. A peptide can be pure on paper and degraded by a broken cold chain.
- Scope is bounded. Unless stated, no sterility, endotoxin, heavy metal, or residual solvent testing was performed.
A COA is the best documentary evidence available in an unregulated market. It is not a guarantee, and the only way to know what's in a specific vial is independent testing of that vial.
Frequently asked questions
What is the minimum a peptide COA must include?
Product name with sequence and theoretical molecular weight, a specific batch number, the testing laboratory's name and contact details, a recent analysis date, a purity percentage with its specification, an HPLC chromatogram, and mass spectrometry confirming identity. Anything less can't be verified.
Does a COA have to come from a third-party lab?
Not strictly — in-house COAs exist and can be honest — but an in-house document is self-reported and can't be independently confirmed. A third-party COA from an accredited lab is the gold standard because it can be checked against the lab's own records.
How recent does a peptide COA need to be?
For active stock, testing within the last 12–18 months is the working expectation. Past roughly 24 months, the document says little about material currently in inventory.
Is a COA without a chromatogram still valid?
Treat it as incomplete. Without the chromatogram, the purity figure is an assertion with no supporting evidence, and none of the usual quality checks — peak shape, baseline stability, impurity profile — are possible.
Research use only. This article is for scientific and educational purposes and is not medical, dosing, or investment advice. Research peptides are not approved for human or veterinary use.