How to read a peptide certificate of analysis

A certificate of analysis, or COA, records what a laboratory measured in a submitted sample. Reading it well means separating the sample’s identity, the amount measured, the tests performed and the limits of those tests. Start with the report itself; a purity badge leaves most of that information out.

Start with the sample and the issuer

Open the complete report, including its analytical pages. Record the laboratory, report number, sample identifier, reporting date and material named on the label. If the laboratory provides a verification page, follow the exact report code and compare its record with the document you were shown.

For example, the linked BPC-157 report identifies sample BPC-063, report COA-2026-SC-00978, dated August 14, 2026. It reports a nominal 10 mg sample, a measured content of 10.88 mg and purity of 99.6%. Those are three separate fields describing this tested sample. The issuer’s record can be checked directly. Complete BPC-157 report, issuer verification.

A sample identifier should not silently become a stock-lot number. The next question is whether the supplier documents a link between that submitted sample and the batch currently supplied. A genuine report establishes that the issuer recognizes the document; that alone does not establish which vial a customer receives. In this example, a current-inventory lot match has not been established in the reviewed records.

Read identity, purity and quantity separately

These headings answer different questions:

Table: scroll horizontally to see all columns.

HPLC purity is commonly calculated from the main peak’s area relative to the detected peaks. It is not automatically the percentage of the powder’s total weight that is the intended peptide. Water, counterions and residual solvents require their own assessment. A purity result and a content assay therefore belong side by side. Bachem’s analytical quality-control guide.

Read the method and units before comparing two laboratories. “Purity,” “content” and “assay” are not safe to treat as interchangeable labels. If the report does not explain its mass basis or identity method, that is a useful question for the laboratory. An unexpectedly high or low sample assay is also a reason to clarify the result and its applicability; this article does not turn a sample measurement into a treatment calculation.

Look for the tests that answer the question

A chemical identity or purity test does not measure every possible quality attribute. Endotoxin testing uses specifically suitable methods, and method suitability depends on the product. A report should identify an endotoxin test and result before a reader attributes that finding to it. FDA’s March 2026 pyrogen and endotoxin guidance.

Sterility is another separate subject. FDA’s sterile-manufacturing guidance discusses production controls and microbial testing together; an attractive chromatogram cannot substitute for that evidence. Likewise, a report of chemical content should not acquire a shelf-life or post-preparation stability claim that it never tested. FDA manufacturing and microbiological-control questions.

Keep analytical results and clinical evidence distinct

A COA can make a product record more transparent. It cannot show that a proposed treatment benefits people, establish a patient regimen, or authorize a product for medical use. Canadian drug authorization is checked through the product’s regulatory record, including its Drug Identification Number where applicable. Health Canada’s peptide advisory.

When comparing reports, keep a short record: exact material, sample and lot linkage, issuer verification, method, units, results and stated limitations. That gives a future reader enough information to understand what was established and which questions remain open.

Sources checked September 8, 2026. Educational article; no clinical sign-off or patient instructions.