Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
A Certificate of Analysis (COA) is the single most useful document for judging a specific batch of a research peptide — but only if you know what each section is actually claiming. This is an analytical guide to reading one: what the numbers mean, what they don't, and the patterns that should make you distrust the document in front of you.
Across the 5,030 lab-verified COAs Disclosed Labs currently indexes, 47.8% carry no mass-spectrometry identity result — they report how pure a sample is without proving which molecule it is. 65.7% have been confirmed directly against the issuing lab's own records. The sections below explain why that distinction matters.
Purity is usually the first — and often the only — number a vendor quotes. It is measured by HPLC(high-performance liquid chromatography), which separates the sample into peaks and reports the main peak as a percentage of the total detected area. A result of “99.1% by HPLC” means the dominant peak is 99.1% of what the instrument saw.
What purity does not tell you is which molecule that peak is. HPLC measures the proportionof the main component, not its identity. A convincing purity section shows the method, ideally a chromatogram, and a value reported to a sensible precision. Be wary of a bare “>99%” with no method, no chromatogram, and no reference standard named.
Mass spectrometry (MS, often MALDI-TOF or LC-MS) is the test that confirms identity. Every peptide has an expected molecular mass; MS measures the actual mass of the material. When the measured mass matches the expected mass within instrument tolerance, you have evidence that the molecule really is the one on the label.
This is the section most often missing. A COA with a high purity number but no MS result is telling you the sample is clean without telling you what it is — the two claims are not interchangeable. If identity matters to you, look for a stated expected mass, a measured mass, and confirmation that they agree. HPLC co-elution against a reference standard is a weaker but still useful identity signal.
Purity is a percentage; net peptide content is a mass. A vial labeled with a given amount of peptide may contain less actual peptide than the label states, with the remainder being water, salts, or counter-ions left over from synthesis. A COA that reports net peptide content (measured mass vs. labeled mass) lets you see the gap between what was sold and what is physically present.
A high purity number attached to a vial that contains far less peptide than labeled is still a shortfall — the material present is clean, but there is less of it than claimed. Reading purity and net content together is the only way to catch that.
Beyond the headline purity figure, a thorough COA reports the impurity profile — the smaller peaks alongside the main one. The most informative single number here is the largest individual impurity: a sample that is 97% main peak with one 2% related substance is a very different document from one that is 97% main peak spread across a dozen tiny peaks. Related substances are frequently truncated or deletion sequences from synthesis; their size and number are a quality signal in their own right.
Two panels apply specifically to parenteral (injectable) forms and are not expected on raw powders or other non-injectable forms:
Because these only apply to injectable forms, their absence on a raw-powder COA is not a gap. On an injectable-form COA, though, their absence is a real omission worth noticing — the document is silent on a contamination question that the form raises.
A COA is only as good as its traceability. The document itself can be copied, edited, or fabricated, so the last question to ask is whether you can independently confirm it. Patterns that should lower your trust:
Disclosed Labs cross-references documents against the issuing laboratory's own records where a lab publishes a verification portal; documents that can't be confirmed are indexed as vendor-supplied, and cross-vendor anomalies are surfaced on the Forgery Map.
Apply this to actual documents. Browse the corpus, or jump to the cross-vendor COA view for a specific peptide.
A Certificate of Analysis is a document issued by a testing laboratory that reports the measured characteristics of a specific batch of material — most importantly its purity, its molecular identity, and, for injectable forms, its endotoxin and sterility results. A COA describes one lot at one point in time; it is not a general statement about a brand.
Purity (measured by HPLC) tells you what fraction of the detected material is the main peak — how 'clean' the sample is. Identity (measured by mass spectrometry) tells you WHICH molecule that main peak actually is. A COA can report 99% purity and still not prove the compound is the one named on the label, because purity alone does not identify the molecule. A trustworthy identity claim pairs a high purity number with a mass-spec (or MALDI/LC-MS) result whose measured mass matches the expected mass.
For a lyophilized or injectable peptide, a complete COA typically reports: HPLC purity (%), mass-spectrometry identity (measured vs. expected mass), net peptide content (actual mass vs. labeled mass), an impurity or related-substances profile, and — because the form is parenteral — an endotoxin (LAL/BET) result and a sterility result. Raw-powder and non-injectable forms are not expected to carry endotoxin or sterility panels.
Common patterns that should reduce your trust in a document: no mass-spec identity (purity without proof of which molecule it is); a lab name with no verification code or portal to check the report against; the same lot number appearing under two different brands; a tested date that predates the batch or never changes across 'new' batches; mismatched fonts, misaligned tables, or an editable-looking PDF; and a purity value quoted with no method, no chromatogram, and no reference standard.
No. A COA is an analytical record of what a lab measured in one batch — identity, purity, contamination markers. It is not a safety determination, not a medical endorsement, and says nothing about effects in a person. Reading a COA well tells you whether the document is internally consistent and independently verifiable; it does not tell you anything about how a substance should be used.
This is an analytical guide to reading laboratory documents. It is informational only — not medical, safety, or usage advice.
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