Research & Guides

How to Read a Peptide COA: A Batch Documentation Checklist

October 26, 2026

A certificate of analysis is useful when you can connect it to an identified sample and understand what was measured. A large percentage on a PDF is not enough. The useful question is: what does this particular document establish about this particular material?

This checklist focuses on traceability: the link between a product, a batch, a report and the available evidence. For an explanation of instruments themselves, see our separate HPLC versus mass spectrometry guide.

1. Match the name and batch before reading the headline result

Record the product name exactly as printed, including any salt, copper complex, fragment or blend wording. Then copy the report number, batch or lot identifier and issue date. Compare these with the material you are asking about. Similar names are not a documented match.

If a report and product use different identifiers, ask the supplier to explain their relationship. Record the explanation and whether supporting records were provided. Do not silently treat an unanswered question as a successful check.

2. Identify the sample the report actually covers

Was the submitted sample bulk powder, an individual vial or another preparation? Does the report state who supplied or selected it? Those details define the scope of the result. A test on a named bulk sample does not itself establish that every finished vial or every advertised strength was tested.

ChinaPeptideshop’s COA page currently publishes original supplier-provided PDFs described as named bulk-sample or batch documents. The page explicitly distinguishes those records from testing every vial or strength. Contact support to confirm the supplied batch; a document for another lot is not a substitute.

3. Keep identity, purity and quantity in separate columns

Identity asks what material was detected. A purity or impurity measurement asks a different question, under a stated analytical procedure. Quantity or content asks how much of the analyte was measured in the sample. None of these headings should be replaced by another simply because a report uses a percentage.

For example, a chromatographic area percentage is not automatically a per-vial mass measurement. Likewise, a number labeled “sample quantity” may describe the material submitted, rather than the amount independently measured in a finished vial. Read the result label, units and method together.

ICH Q2(R2), published by FDA in March 2024, distinguishes analytical purposes including identity, assay and purity or impurity testing. That framework helps explain why one result should not be stretched to answer every question. Citing the guideline does not mean that a supplier’s report or product has FDA approval or demonstrated compliance with it.

4. Check the issuer and the original document

Preserve the full original PDF, including every page, rather than a cropped screenshot. Note the named issuer, document reference, test dates, stated methods, result units and any qualifications. If a verification service is offered, reach it through the issuer’s independently located official contact or website. Record whether the report was actually confirmed.

A logo, signature image or QR code is a starting point for checking, not proof on its own. Supplier-provided documentation should be described that way. ChinaPeptideshop’s quality information page states that previous independent report links and verification remain retired; this checklist does not reinstate or authenticate them.

5. Write down the unanswered questions

Use “not stated,” “not supplied” or “not verified” when that is the accurate answer. Useful follow-up questions include whether the report matches the supplied lot, what a numerical result measures, whether a quantity is a submitted sample amount, and which tests were outside the report’s scope.

Do not infer sterility, endotoxin results, long-term stability or suitability for human use from an unrelated purity figure. If an attribute matters to a legitimate research activity, establish what evidence is available for that attribute separately.

Download the blank documentation worksheet

Download the peptide COA traceability worksheet (CSV). It contains fields for the product, batch, issuer, sample scope, analytical results, verification status and unresolved questions. The file is a blank organizational tool, not a test report, certification or automated pass/fail assessment.

A well-documented review does not need to claim more than the evidence supports. Its value is that another reader can see what matched, what was measured and what remains open. That makes the next conversation with a supplier or laboratory more specific and more useful.