Certificate of analysis: how to read one

A certificate of analysis (CoA) is a document issued by an independent analytical laboratory that records test results for a specific batch of a compound. It names the compound, the laboratory's own task number, the analysis date, the methods used, and the values measured — purity by HPLC, identity confirmation by mass spectrometry, and in many cases moisture content and physical appearance. Without that document, signed by a laboratory with a verifiable name and address, any purity claim is an assertion without a foundation.

What tests a CoA documents

The most consequential test in a research peptide CoA is HPLC purity — high-performance liquid chromatography. The result is expressed as a percentage: the area of the compound's peak divided by the total integrated area in the chromatogram. A result of 99.7% means that 99.7% of the material detected corresponds to the declared compound. The remaining fraction may be degradation products, synthesis impurities, or residual solvents.

The second standard test is identity confirmation, most commonly by mass spectrometry (MS) or amino acid analysis. This confirms that the molecule analyzed is actually the one on the label — not an analog, not a structurally similar compound with a different sequence.

Other fields that appear in a complete CoA:

• Appearance: whether the lyophilized powder has the expected color and texture.
• Moisture content: relevant to batch stability during storage.
• Actual content versus label claim: some laboratories weigh the vial contents and compare against the stated amount. Small discrepancies within ±10–15% are within normal tolerances for lyophilized peptides.

That last point appears in the reports PeptoClinic publishes for its lots. The Janoshik Analytical report for Retatrutide (task 136921) declared 10 mg on the label; the laboratory recorded 11.96 mg of actual content.

Why the issuing laboratory defines the document's value

A CoA is worth exactly as much as the laboratory that signs it. A PDF with no laboratory name, no physical address, and no verifiable task number is not a certificate — it is a document formatted to look like one.

Three elements make a CoA verifiable:

The laboratory name and address. An analytical laboratory that works for third parties has a public presence. It appears in search results, it has a website with contact information, and in many cases it holds accreditation from an external body. Search "Janoshik Analytical" and you find the laboratory, its services, and its contact details — that is traceable.

The laboratory's task number. Every analysis a laboratory runs is recorded under a unique identifier. That number is what enables external verification: if the laboratory has a public lookup portal, entering the task number returns the original report. Without that number, there is no way to distinguish a genuine CoA from an edited copy.

The date of analysis. A CoA does not expire, but it does have a reference date. If material was analyzed in 2024 and you receive it in 2026, the CoA documents the batch's condition at the time of analysis — not its current condition. Storage conditions during that interval are a separate variable.

PeptoClinic publishes four reports issued by Janoshik Analytical, all dated 2026-04-13, all with verifiable task numbers. You can review them on the quality page.

How to read the numbers in a CoA

The HPLC purity figure most commonly cited in research peptide documentation is the area percentage. To interpret it correctly:

The percentage reflects the relative area of peaks in the chromatogram. A result of 99.893% means that the signal for the compound of interest occupies 99.893% of the total integrated area. What remains may be synthesis impurities or minor degradation products — the identity of those impurities is rarely detailed in a standard CoA.

The threshold generally applied to reference research peptides is above 98%. The four lots published by PeptoClinic have a floor of 99.669% — the lowest result recorded, for MOTS-c (task 136923). The highest is 99.893% for Retatrutide (task 136921). Reporting the floor rather than the ceiling is the honest way to represent a catalogue's quality standard.

If a supplier publishes only the best result from its analyses without disclosing the rest of the catalogue, that is selective reporting, not a representation of the lot range.

How to verify a CoA before working with a supplier

Step 1: find the laboratory. Confirm it exists, has a public presence, and is a real analytical facility — not a generic name that returns no results in any sectoral directory or accreditation registry.

Step 2: locate the laboratory's task number. If the CoA shows only the supplier's internal batch number — not the laboratory's own identifier — it is not externally verifiable. These are two distinct identifiers: the laboratory task number enables a query in the external portal; the supplier batch number is the supplier's internal nomenclature.

Step 3: use the laboratory's verification portal if one exists. Janoshik Analytical has an online verification system. Two of the four reports that PeptoClinic publishes carry a working verification link; the other two have a registered task number but the portal returns an error at that specific URL. That is documented as-is in the catalog — without representing a broken link as functional.

Step 4: cross-reference the report against the vial. The compound name, the label quantity, and the lot number on the vial should match those on the report. If anything does not align, request clarification before accepting the lot.

A supplier that cannot provide a CoA with a task number from a named laboratory is asking for trust without any basis for verification. For research material, that is not a sufficient basis.

What documentation ships with a PeptoClinic order

PeptoClinic supplies research peptides with the lot's CoA included with each shipment. The available reports cover Janoshik Analytical analyses for Retatrutide, MOTS-c, GHK-Cu, and BPC-157 + TB-500, all analyzed on 2026-04-13.

For documentation on other compounds or additional documentation requirements for a specific research program, contact [email protected]. Pricing and shipping inquiries for Argentina are handled through the quote form — no prices are published. The Argentina shipping page covers import conditions for laboratory reference material.

Research use only

All material supplied by PeptoClinic is strictly for research use only (RUO): in vitro work and laboratory environments.

No compound in the catalogue is a medicine, a supplement, or a food. None has been approved or is intended for human or veterinary consumption, diagnosis, or treatment of any medical condition. No claim on this site has been evaluated by the FDA, ANMAT, or any equivalent regulatory authority.

PeptoClinic is not a pharmacy, a clinic, a telehealth provider, or a source of guidance on administration or protocols. Requests for information about use in people are outside the scope of this operation.