How to Read and Verify a Peptide COA

A certificate of analysis (COA) is the laboratory’s record of what was measured on a specific sample of a specific lot. For research peptides it is the main piece of documentation that links the material in a vial to objective analytical data. Reading a COA well means knowing which fields matter, what each method can and cannot show, and how to check that the document is genuine. This guide walks through each part of a typical peptide COA, using the format of the certificates posted on our Certificates of Analysis page as examples.

1. The header: who tested what, and for whom

Start at the top. A COA should name the testing laboratory and its address, the product name and labeled quantity, and the client the testing was performed for. Our ILS Laboratories certificates, for example, show the laboratory’s San Diego address, the product (for example “AOD-9604 – 10mg”) and the line “Tested for: M Rogue Research”. Some suppliers post COAs issued to their manufacturer instead; that is not necessarily a problem, but the client field tells you whose sample was tested, and you should read the remaining fields with that in mind.

Next come the identifiers: a COA or accession number, a lot number, the date the sample was received and the date it was analyzed or reported. The lot number is the most important of these. A COA describes only the lot it names, so check that the lot on the certificate matches the lot printed on your vial. A COA for a different lot is useful context, but it is not documentation for your material.

2. The summary box: purity, content and pass/fail

Most COAs put the headline results near the top: the identity, the purity percentage and an overall status. Look closely at three things. First, the purity value and the method that produced it (usually HPLC). Second, the specification the result was judged against. A result of 97.46% “passes” a specification of ≥95.0%, but it is still 97.46%, so record the number rather than the pass flag. Third, the net peptide content, which is reported in milligrams.

Net content and purity are different measurements. Purity tells you what fraction of the peptide-related material in the chromatogram is the target sequence. Net content tells you how much peptide is in the vial. A 10mg-labeled vial with 10.44 mg net content and 97.46% purity contains slightly more than the labeled mass of peptide material, of which roughly 97.5% by UV peak area is the target peptide. Lyophilized peptides also contain counter-ions (often acetate or trifluoroacetate) and residual water, which is one reason content and labeled mass are rarely identical.

3. The analyte table: methods and specifications

The analyte table lists each test, its specification, the result, the unit and the status. On a typical HPLC-only certificate you will see peptide purity (HPLC), net peptide content, identity and, on many current COAs, a contaminant screen. Our ILS certificates include a fentanyl immunoassay screen with a 50 ng/mL cutoff, reported as “Not Detected”.

Pay attention to how identity was established. “Identity (HPLC-RTM)” means the main peak’s retention time matched a reference standard under the same chromatographic conditions. That is a useful check, but it is indirect: it shows the sample behaves like the reference on that column, not what its mass is. “Identity (LC-MS)” means the molecular mass of the main component was measured and matched to the expected value. Our BPC-157 COA from Freedom Diagnostics reports LC-MS identity, while the ILS COAs report HPLC retention-time identity. Neither is wrong, but they are different levels of evidence, and a good COA states which one was used. Our guide LC-MS vs HPLC: How Molecular Identity is Confirmed explains the difference in detail.

4. The chromatogram

A chromatogram is a plot of detector signal (usually UV absorbance at 214 nm or 220 nm) against retention time. The target peptide should appear as one dominant, sharp peak. Smaller peaks before or after it represent impurities such as truncated or deletion sequences, oxidized forms or synthesis by-products. Purity by area normalization is the main peak’s area divided by the total area of all integrated peptide peaks. Check that the main peak is labeled, that the axes are readable and that the stated detection wavelength matches the method description. For a blend, expect one main peak per component; our CJC-1295 + Ipamorelin Blend COA shows two (see the CJC-1295 + Ipamorelin Blend research compound).

5. Mass spectrum (when present)

If the COA includes LC-MS data, it will show a mass spectrum with peaks labeled by mass-to-charge ratio (m/z). Peptides often appear as several charge states, for example [M+H]+ and [M+2H]2+. Check that the observed m/z values correspond to the expected molecular weight. For BPC-157 (1419.5 g/mol), the singly charged ion appears near m/z 1420 and the doubly charged ion near m/z 710, which is what the Freedom Diagnostics certificate shows (see the BPC-157 research compound).

6. Notes, methodology and limitations

Read the small print. Methodology notes state how purity was calculated (for example, RP-HPLC area normalization at 214 nm, with non-peptide impurities excluded) and include the laboratory’s disclaimer that results apply only to the sample submitted. This matters: a COA documents the tested sample, not every vial ever produced. It also typically states that product names and lot details were supplied by the client and not independently verified by the laboratory.

7. Verifying authenticity

A COA is only useful if it is genuine. Practical checks include the following. Confirm that the laboratory exists and that the address and phone number match its public website. Use any verification mechanism printed on the document: ILS certificates carry a QR code, an access code and a verification link at portal.ils-lab.com, and Freedom Diagnostics certificates carry a QR code. Check that the COA number, lot number and dates are internally consistent. Look for signs of editing, such as mismatched fonts or misaligned values. Finally, compare the certificate’s product name, quantity and lot with your vial label.

8. A quick checklist

Before relying on a COA, confirm: the lot number matches your vial; the purity value and method are stated; the net content is reported; the identity method is named (retention time or mass spectrometry); the chromatogram is legible with a dominant main peak; the dates are recent and consistent; and the certificate can be verified with the laboratory. You can view every COA we currently hold on our Certificates of Analysis page. Products whose third-party COA is still pending, such as Epithalon and Selank, are marked “COA coming soon” rather than given a purity figure.

All compounds are intended strictly for laboratory and scientific research purposes only. Not for human or animal consumption.