How to Read a Peptide Certificate of Analysis (COA)
Match a peptide COA lot number to your material, read identity and purity separately, and check the method behind every reported value.
A peptide Certificate of Analysis (COA) is useful only when it matches the batch you actually received. Start with the batch number, then read each reported test in the context of its method. A single purity figure does not tell the whole story.
This guide explains a practical way to review COA documentation for research materials. It does not make a claim about any particular batch. Always read the document for the specific batch in front of you.
What is a peptide COA?
A COA is a document reporting tests and results for a stated batch of material. Look for the product name, batch or lot identifier, reported measurements, and any test methods or criteria shown. A product listing describes an item in the catalog; the COA gives information about a particular batch. Results for one batch should not be assumed to apply to another.
Medical Peptide Store lists published documents in its COA Library by compound, strength, and lot number. The library lets you view or download the available PDF for a listed lot. It distinguishes current and previous batches.
1. Match the document to your batch
Check the batch number on the packing list that came with your order. The store’s Quality & Testing page says the packing list names the batch. Search for that exact identifier in the COA Library, then compare the compound and strength shown in the library with your order and the PDF.
Read the entire identifier, including letters, numbers, and punctuation. Similar looking codes are not proof of a match. If you cannot find the batch or the PDF is not published, contact the store with the batch number from your packing list. The Quality page says the team can share what is available for that batch.
2. Separate identity from purity
Identity and purity answer different questions. An identity result addresses whether the tested material matches the intended substance under the reported test. A purity result describes what the stated analytical procedure found about the sample. Neither result replaces the other.
Read the label attached to each number. “Purity,” “area percent,” and a result from a named test are not automatically interchangeable. If the COA does not explain what was measured or how a percentage was calculated, ask for clarification before comparing it with another document.
Medical Peptide Store says it publishes identity, purity, or endotoxin numbers only when an independent test confirms the number for that specific batch. A missing number is therefore an unanswered question, not a result you can infer.
3. Read the method and criteria beside each result
For every reported value, look for the test name or method, the result, units where relevant, and any acceptance criterion. Note the test or document date if one is provided. A result without enough context may be difficult to interpret or compare.
Different methods can examine different properties or report results in different ways. Keep the COA’s own wording when recording a result. If the method, criterion, or unit is unclear, ask the supplier what the field means. Do not convert one type of percentage into another or treat a “pass” entry as a numeric result.
4. Notice what the document does not say
A COA reports the tests shown on that document. It does not establish that every possible test was performed. Do not interpret a blank field or an absent test as a pass. Do not treat a general product description as batch-specific evidence.
Ask a focused question when information is missing: Which batch does this PDF cover? What method produced this result? What criterion was applied? Is there a more recent document for this batch? Keep the answer with your batch records.
A short COA review checklist
Match the batch number on your packing list to the COA Library entry and PDF.
Confirm the compound and strength match your order.
Read identity and purity as separate reported results.
Record each result with its stated method, units, criteria, and date where available.
Ask about missing or unclear fields rather than filling gaps by assumption.
The COA Library is the starting point for published batch documents. For more about how the store handles documentation and unpublished COAs, see Quality & Testing. These materials are sold for laboratory research and are not for human or animal use.