How to Read a Certificate of Analysis (COA) for Research Peptides

1. Does the report belong to your batch?

Find the batch (lot) number on the report and match it to the one on your vial label and your order. A report for a different batch tells you nothing about the vial in front of you. Also check the compound name and the stated amount per vial.

2. Who ran the test, and when?

A third-party report names the laboratory that did the testing, usually with its contact details, and carries a test date. “Independent” means the lab is a separate company from the seller. Check that the date is plausible for the batch: a report dated long before the batch was made, or long after the product went on sale, deserves a question.

3. Which methods were used?

Most peptide reports use two methods: HPLC (high-performance liquid chromatography) for purity, and mass spectrometry (MS) for identity. Our guide How Peptide Purity Is Tested explains both. A report that states a purity percentage without naming the method is harder to evaluate.

4. Read the purity result carefully

HPLC purity is normally the percentage of the total detected peak area that belongs to the main peak. Look at the chromatogram itself, not only the number: a clean report shows one dominant peak. See Purity vs Quantity for why a high purity percentage does not mean the powder is that percent peptide by weight.

5. Confirm identity

Mass spectrometry compares the measured molecular mass with the expected mass of the compound. The two should agree within the instrument’s tolerance. If the report lists an observed mass, compare it with the compound’s published molecular weight. Our product pages list molecular weights in the Specifications tab for the compounds that have one.

6. Know what a COA does not cover

• Sterility, unless a sterility test is listed.
• Bacterial endotoxin, unless an endotoxin (LAL) test is listed.
• Heavy metals, residual solvents or other contaminants, unless they were tested.
• Net peptide content (the actual weight of peptide per vial), unless an amino acid analysis or similar test is listed.
• Every other vial in the batch. A COA describes the sample that was tested; it does not prove that every vial is identical.

7. Check that the report is genuine

• Are the lab’s name, address and contact details shown?
• Do the batch number, compound and amount match across the report and the vial?
• Is the image complete and legible, not cropped or edited?
• Does the lab offer a way to verify a report, such as a report number or QR code? If so, use it, or email the lab directly.

Each Pacific Coast Labs product page links to its certificate of analysis. Open it, run through this list, and contact us if anything does not match.