How to Read a Peptide COA: 6 Checks, With a Real Example

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Research use only. Peptides supplied by Peptryn are sold strictly for in vitro and preclinical laboratory research. They are not approved by the FDA for human or veterinary use, and nothing here is medical advice, a dosing recommendation, or an instruction for self-administration. This guide explains how to read a laboratory document. It does not tell anyone how to use a peptide.

Quick answer: A certificate of analysis (COA) reports what a laboratory measured in one sample on one date. To read a peptide COA, check six things in order: the lot, lab and dates; the identity result; the HPLC purity; the measured quantity; whether endotoxin and sterility were tested; and what the document leaves out. Then confirm the report exists on the lab’s own site. Our COA explainer covers the vocabulary, and this page walks through a real report.

Last verified October 11, 2026. The example is Peptryn’s BPC-157 10 mg certificate from MZ Biolabs, lot 2026-08-05. It shows how to read a report and is not a quality ranking.

1. Lot, lab and dates

A COA applies to the sample the lab received, not to every vial with the same name. Find the compound and size, the lot, the lab and the client, and the analysis date. In the example, the lot reads 2026-08-05, the analysis date is 2026-08-24, the lab is MZ Biolabs in Tucson, Arizona, and the client is Peptryn.com. Confirm that the lot printed on the vial matches the lot on the certificate. In our library the lot field is a date, and 2026-08-05 appears on 11 reports for different compounds, so read the compound and size as well. A report with no lot ties the document to very little.

2. Identity

Mass spectrometry measures molecular mass. A good report prints the expected mass and the measured mass. The example expects 1418.70 Da and measures 1418.78 Da, and it states “Molecular weight confirmed”. A match supports the claim that the vial holds the named compound. It does not measure purity, quantity or endotoxin.

3. Purity

HPLC separates the sample and reports each peak’s share of the detector signal. The example lists 11 detected peaks. The main peak is 99.50% and the largest impurity is 0.40%. That is an area percentage, and it does not count water, salts or counterions. Our guide to what 99% purity means covers the arithmetic.

4. Quantity

Some certificates print a measured amount per vial. The example measures 12.16 mg in a vial labeled 10 mg, which is 121.6% of the label, alongside the 99.50% purity. Purity and quantity are different numbers, so read both. Across the 16 single-compound certificates Peptryn had published on October 10, 2026, measured quantity ranged from 91.4% to 162.6% of the labeled amount; our data report explains the earlier set. A certificate with only a purity figure does not say how much peptide is in the vial.

5. Endotoxin and sterility

Endotoxin is a separate test on a separate vial. The example has its own one-page endotoxin report, dated August 13, 2026, with a negative result and a positive-control recovery inside the report’s own 50% to 200% validity window. Sterility is a different test again, and Peptryn has not published a sterility report for any listing. MZ Biolabs states on its COA testing page that purity testing does not test for sterility or endotoxins, heavy metals, or pH, so a purity-only certificate says nothing about them.

6. What the certificate leaves out

The example prints no accreditation statement, measurement uncertainty, reference standard or limit of quantification. It has no sample-receipt date or chain-of-custody line. Its results describe the sample tested and nothing else, which is why the lot match in step 1 matters. Accreditation is specific to a lab and a scope of tests, and a certificate that names one should say which tests it covers.

Check the report on the lab’s own site

A PDF on a seller’s website is a copy. Look for a QR code or lookup on the lab’s own site and compare it with the file line by line. In the example, the QR code opens the lab’s record for the certificate. Other labs use a task number and a unique key or a report number. Our Janoshik report guide shows how one key-based lookup works and what verification does not prove. See also peptide testing explained and the full COA Library, including the BPC-157 10 mg certificate used above.

Peptide COA: common questions

How do I read a peptide COA?

Check six things in order: the lot, lab and dates; the identity result from mass spectrometry; the HPLC purity; the measured quantity per vial; whether endotoxin and sterility were tested; and what the document leaves out. Then confirm the report exists on the lab’s own site.

What should a peptide COA include?

At minimum: the compound and size, the lot, the lab and client names, the analysis date, a purity figure with the method, an identity result with expected and measured mass, and the measured quantity. Endotoxin, sterility, heavy metals and counterion content are separate tests that appear only if they were run.

Is 99% purity on a COA enough?

No. HPLC purity is the main peak’s share of the signal. It does not show how much peptide is in the vial, whether the molecule is the right one, or whether endotoxin or sterility were tested. Read purity together with identity and quantity.

How do I know a COA is real?

Open the copy on the lab’s own site through a QR code, an ID or a task number and key, and compare it with the file you were given. A match shows the lab issued that report. It does not show that your vial is the tested one, so also match the lot.

All products on peptryn.com are intended for laboratory research purposes only. They are not drugs, foods, dietary supplements or cosmetics, and they are not for human consumption, self-administration, or veterinary use. You must be 21 or older to buy. The information on this page has not been evaluated by the U.S. Food and Drug Administration and is not intended to diagnose, treat, cure, or prevent any disease. Nothing here should be construed as medical advice.