How to read a peptide certificate of analysis

Which certificate does this COA guide walk through?

This guide walks through one real certificate from top to bottom: the one for our Selank 10mg, lot ABL-SEL-2605, which names Vanguard Laboratory as the testing laboratory and is dated June 18, 2026. You can open it from the product page or the COA library and follow along. It is two pages long; page two repeats the figures from page one in a table.

We chose it because it reports four kinds of test, and because it is a good example of what a certificate can leave out. Our testing page covers the basics using the BPC-157 certificate. Here we go further: for each field, what it tells you and what it does not.

Who is the client and who is the laboratory on a COA?

On this certificate the client is our supplier, and the laboratory that ran the test is named in the "Source Laboratory" field, not the letterhead logo. The top of page one reads "Certificate of Analysis", with a sample ID (V260211-4 009), the lot and the date issued. Below the product name is a "Client" line. The client is whoever sent the sample and paid for the analysis; on this certificate it is our supplier, not Aion. That is common: research-peptide certificates are often commissioned by a manufacturer or supplier, and what matters is that the certificate still ties to the lot you receive.

The logo in the corner reads "Food & Environment Safety Analytical Lab". That is not the laboratory that ran this test. The same letterhead appears on every certificate in our supplier's library, which between them name four different laboratories. The laboratory is stated in the "Source Laboratory" field at the foot of page one, and again under "Testing Location" on page two: Vanguard Laboratory. When a certificate's logo and its named laboratory disagree, go by the named field, and ask the seller which one ran the analysis.

What do the sample name, lot and dates on a COA tell you?

They tie the certificate to one batch, and to the days the laboratory received the sample and issued its report. The sample name, "Selank 10mg / ABL-SEL-2605", is the product and the lot together. The lot is the single most important thing to check: a certificate describes one batch, and it says nothing about a different one. The lot printed here is the lot recorded against the product on our site.

The sample ID, testing ID and accession number are all V260211-4 009. That is the laboratory's own reference for this sample, and it is what the laboratory would need to find its record.

There are two dates. "Date Received" is June 16, 2026, when the laboratory logged the sample; "Date Issued" is June 18, 2026, when it issued the report. Neither is a manufacture date or an expiry date, and this certificate states neither. A certificate tells you what the sample was on the day it was measured.

"Unit Mass" lists three figures: 10.86 mg, 10.11 mg and 10.80 mg, against a labelled 10 mg. The certificate does not say so, but the three parallel figures here and in the purity field read as three vials measured separately. It also does not say whether unit mass is the total weight of powder or the amount of peptide in it, which matters because a lyophilised peptide also contains water and counter-ions.

What does the HPLC purity figure on a COA mean?

The purity figure is an HPLC area percentage measured at 214 nm, and on this certificate it is a floor of >99.80% rather than a point value. The method line reads "HPLC-UV/VIS; ICP-MS; LAL pass; USP <61> no growth". Only the first item is the purity method; the rest are the other tests, covered below. The HPLC parameters list a C18 column (XBridge Peptide BEH), a mobile phase of 0.1% formic acid in water and in methanol, a flow rate of 1.0 ml/min and detection at 214 nm, the wavelength at which peptide bonds absorb. Missing are the gradient, the run time and a chromatogram, so you cannot see the separation the figure came from.

"Chromatographic Purity" reads ">99.80%, >99.80%, >99.80%". Purity by HPLC is an area percentage: the area under the main peak divided by the total area of every peak the detector recorded at 214 nm. Here each figure is a floor rather than a number: the main peak was at least 99.80% of the total, and the laboratory reports nothing finer.

Area percentage has known blind spots. It counts only what elutes from the column and absorbs at the detection wavelength, so water, salts and counter-ions such as trifluoroacetate are invisible to it. An impurity that elutes at the same moment as the main peak is counted as main compound. Synthetic peptides carry characteristic related impurities (deletion and insertion sequences, diastereomers, oxidised forms, leftover protecting groups), and whether a method separates them depends on how it was developed. So purity is not the same as peptide content, and pharmacopoeial specifications for peptide drugs treat identification, purity and assay as separate tests. For what a gap of a point or two means in practice, see Peptide purity: 98% vs 99% in practice.

Does this COA confirm the peptide's identity?

No: it confirms that the sample is one very pure substance, but not that the substance is Selank. The "Sample Information" block gives a molecular weight of 751.89 g/mol and the formula C33H57N11O9. Both are correct for Selank, but they are reference values for the compound named, not measurements. A certificate can print the right formula for a vial that contains something else.

Identity is a separate test. On some of our other certificates, such as the BPC-157 one, the method line includes LC-MS, which measures the mass of what elutes in the main peak. For Selank, a mass spectrum would be expected to show the protonated molecule near m/z 752.44, from its monoisotopic mass of 751.434. Another approach is to run a reference standard alongside the sample and compare retention times. This certificate does neither, so it confirms that the sample is one very pure substance, but not that the substance is Selank. HPLC vs mass spec: what each test proves explains why the two methods answer different questions.

What do the heavy metal, endotoxin and microbial tests on a COA show?

All three read clean, but the certificate states no limit for heavy metals or endotoxin, so those readings cannot be checked against a specification. Heavy metals were measured by ICP-MS, and the summary gives arsenic at 0.01 ppm and lead at 0.02 ppm. Those are low figures, but the certificate states no limit to compare them with, and it reports only those two elements; cadmium and mercury, often tested alongside them, are not listed.

"LAL pass" refers to the Limulus amebocyte lysate test for bacterial endotoxin. The certificate gives no measured value in endotoxin units and no limit, so "pass" cannot be checked against a specification.

"USP <61> no growth" refers to the United States Pharmacopeia's microbial enumeration tests, which count bacteria, yeasts and moulds in a non-sterile sample. No growth is a clean reading, but USP <61> is not a sterility test (that is USP <71>), and the certificate does not state how much material was tested.

Is this COA signed, and how can you verify a certificate?

This certificate carries no signature, and the strongest check is to have the laboratory itself confirm it, quoting the laboratory's sample ID. The signature line above "Source Laboratory" is blank. In its place the certificate reads "Authorized report on file" and "Batch documentation file". There is no analyst's name, no approver, no accreditation statement and no verification code. The footer line notes that the product details and vial image were prepared for the client's recordkeeping, so the photograph is the supplier's, not a picture of the sample the laboratory received.

A certificate is strongest when the laboratory itself can confirm it, through an online lookup or a reply to an enquiry quoting the sample ID. This one has no online lookup. The laboratories named on our supplier's certificates confirmed them to us in October 2026, and we show a verification link on the product page wherever a laboratory offers one. If you want to check a certificate yourself, quote the laboratory's sample ID rather than the seller's lot code, and ask the laboratory directly. For warning signs beyond the ones above, see Red flags in a peptide COA: spotting a fake.

References

1. D'Hondt M, Bracke N, Taevernier L, et al. (2014). Related impurities in peptide medicines. J Pharm Biomed Anal. [REVIEW] PubMed record for reference 1, D'Hondt 2014
2. Vergote V, Burvenich C, Van de Wiele C, et al. (2009). Quality specifications for peptide drugs: a regulatory-pharmaceutical approach. J Pept Sci. [REVIEW] PubMed record for reference 2, Vergote 2009
3. Sharma N, Kukreja D, Giri T, et al. (2022). Synthetic pharmaceutical peptides characterization by chromatography principles and method development. J Sep Sci. [REVIEW] PubMed record for reference 3, Sharma 2022

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