Understanding Certificates of Analysis

A Certificate of Analysis is a document summarising what a laboratory tested, how, and what it found. In the research peptide market these are widely referenced and unevenly understood. They are also not standardised — content and detail vary considerably between laboratories, and "COA" is applied loosely to everything from a single-page purity summary to a full multi-method analytical package.

That variation is the reason it pays to read the document rather than the claim attached to it. What follows covers the fields commonly encountered on analytical reports for research peptides, what each one is doing, and what a report of this kind cannot establish. Because formats differ, treat these as fields that are typically present rather than a description of any particular laboratory's template — not every report includes every one.

Product or compound name

The report should state the material analysed, and that identifier should match the product it is attached to.

Peptides are commonly known by several designations at once — a research code, a sequence-derived name, a CAS registry number. Each identifies the compound with a different degree of precision, and a CAS number is the least ambiguous. Where one is present it is the most reliable point of comparison, which matters because related compounds carry confusingly similar names.

Testing laboratory

Reports usually indicate who performed the analysis. The point of interest is whether that party is independent of the supplier.

In-house testing is not inherently unreliable — many manufacturers run capable laboratories. But it places the supplier in the position of grading its own material, and an independent laboratory removes that conflict.

Some reports reference the laboratory's accreditation. ISO/IEC 17025 is the international standard covering competence, impartiality, and consistent operation of testing laboratories, and accreditation to it addresses personnel competence, equipment calibration, method validation, and measurement traceability.[1] Where that is absent, its absence is not evidence of a problem — the report is simply not offering that assurance.

Analysis date

The date tells you when the material was in the state the report describes.

This matters because peptides degrade. Rates vary by compound and depend heavily on storage, but no peptide is indefinitely stable — stability frameworks exist precisely because quality changes with time under temperature, humidity, and light.[4] A result generated some time ago describes the material as it was then, not necessarily as it is now. That is still meaningful evidence; it is simply evidence with a timestamp attached.

Where a report carries a lot or batch number, that identifier connects the document to a physical quantity of material. Without it, a report describes an analysis rather than a specific batch.

Test method

The method section is the part most often skipped and most often worth reading.

For a purity determination by HPLC, method details may include the column, the mobile phase, the gradient, the detection wavelength, and the run duration. These determine how well the method separated the main compound from closely related substances, and therefore how the figure should be read.[2] Validation guidance asks for demonstrated resolution between the two closest-eluting components precisely because this varies by method.[3] Two results produced by different methods are not automatically comparable.

Where identity has been assessed, the report will normally indicate the technique — commonly mass spectrometry — and may give the observed molecular mass alongside the theoretical value calculated from the sequence.

A percentage given without any indication of how it was obtained cannot be placed in context. That does not make it wrong. It makes it uninterpretable, which for evaluation purposes amounts to something similar. Background on the techniques is in what is HPLC testing.

Result

The result is the finding itself, and its meaning depends entirely on what was measured.

A purity result from HPLC is conventionally reported by area normalisation: the main peak's area as a percentage of total integrated peak area.[2],[5] This is a relative figure — the main component's share of what the detector registered, not of everything in the vial. Material that does not absorb at the detection wavelength contributes little while still occupying mass.

An identity result is generally a comparison rather than a percentage: the observed mass set against the expected mass, with the report indicating whether they agree within tolerance.

Many reports also reproduce the underlying data rather than only the conclusion. Where the raw chromatogram or spectrum is included, the shape of the baseline and the presence of minor peaks convey information a summary figure cannot.

Neither measurement addresses how much peptide a vial contains. That is covered in how peptide purity is measured.

Report or verification link

Some laboratories provide a route to confirm a document against their own records — a reference number, a portal, a QR code, or a hosted copy. This is useful because a PDF is trivially editable and an independently hosted original is not. Where no such route exists the report is not thereby suspect; verification mechanisms are simply not universal.

Limitations of a report

A Certificate of Analysis is a snapshot of specified tests performed on a specified sample at a specified time. Four things follow from that, and they are easy to lose sight of.

It reports only the tests actually carried out. A purity and identity report says nothing about sterility, endotoxin, microbial content, residual solvents, or heavy metals unless those analyses were performed and included — each is a separate determination by a separate method.[5]

It describes the sample submitted. How representative that sample is of a wider batch depends on sampling practice, which reports rarely detail.

It describes the material at the time of testing — not on arrival, and not after storage.

And it is bounded by its own method. A purity figure reflects what that method could resolve and what its detector could see.

None of this makes analytical reports less valuable; they remain the most substantive evidence available about research material. Their value comes from reading them as bounded technical documents rather than general certificates of quality.

How Peptiva publishes reports

Peptiva's position is that a purity claim should be checkable. Our peptides are tested by Liquid Labs, an independent third-party laboratory, and the reports are published on the Test Results page rather than summarised into a figure on a product listing.

Our release standard is ≥99% purity by HPLC, and the Quality Control page sets out how it is applied. Where a report exists, our intention is that the document itself is available rather than only the conclusion drawn from it.

All products supplied by Peptiva are intended strictly for in vitro research and laboratory use. They are not for human or animal consumption, nor for diagnostic, therapeutic, or medicinal purposes. This article is provided as general analytical background and is not laboratory, medical, or regulatory advice.