How to read a peptide COA (certificate of analysis), 2026

The short answer

To read a peptide COA, first match the batch number to the product you hold, then check who ran the test and when, then read each result against the question it actually answers: HPLC purity tells you how clean the sample is, mass spectrometry tells you whether it is the right molecule, and a quantity or content result tells you how many milligrams are present. A single purity percentage, however high, only answers the first of those questions.

The rest of this guide goes through a COA field by field, explains what each one can and cannot prove, and then walks through the published Celyfe NAD+ certificate as a worked example.

Purity, identity and content are three different questions

Most confusion about COAs comes from treating one number as if it answered everything. Analytical chemists separate the questions because they need different techniques, and a sample can pass one test while failing another. A highly pure sample of the wrong peptide is still the wrong peptide, and a correctly identified, pure peptide can still be under-filled.

Every field on a COA and what it proves

Formats differ between laboratories, but a complete certificate contains the same building blocks. Read them in this order:

• Laboratory name, address and contact: tells you who is responsible for the result. A COA with no lab named is a supplier claim, not a lab report.
• Report or certificate number: the lab's own reference, which it can use to confirm the document is genuine.
• Report date and, ideally, sample receipt date: shows the test is recent and lets you match it to a production window.
• Client or vendor name: shows who submitted the sample. Some testing programmes deliberately omit it from the PDF and show it on their website instead.
• Sample description: the compound name as written on the container, plus any label claim (for example 500mg).
• Batch or lot number: links the result to one production run. This must match the product you received.
• Method: names the technique (HPLC, LC-MS, LAL and so on), and in better reports the column, wavelength or reference to a standard method.
• Result: a number with units, or a clear pass or fail against a stated specification. "Conforms" with no number is weak evidence.
• Specification or acceptance limit: what the result was judged against. A result without a limit cannot pass or fail anything.
• Limit of quantification (LOQ): the lowest level the method can measure reliably. "Not detected" only means below this level.
• Raw data: the chromatogram (a plot of detector signal against time) and, for MS, the spectrum. These let a reader see whether there is one dominant peak or several.
• Signature or authorisation: the name of the analyst or approver, and any accreditation mark with its certificate number.

Reading the HPLC chromatogram

An HPLC chromatogram shows detector response on the vertical axis and retention time on the horizontal axis. Each component of the sample that absorbs UV light appears as a peak when it leaves the column. Purity is calculated as the area of the main peak divided by the total area of all integrated peaks. A 99% result means the main peak accounts for 99% of the UV-absorbing material that the method separated and integrated.

Three things are worth checking on the plot itself. First, whether there is one clear main peak with a flat baseline either side. Second, whether the integration table lists the small peaks rather than ignoring them. Third, whether the run is long enough for later-eluting impurities to appear. A chromatogram cropped tightly around the main peak can hide impurities that elute later.

Because the calculation is a ratio, HPLC purity is blind to anything the UV detector does not see or the method does not separate, which is why the next two sections matter.

Reading the identity result

Mass spectrometry measures the mass-to-charge ratio of ionised molecules. For a peptide, the software usually deconvolutes several charge states into a single molecular mass, which is compared with the theoretical mass calculated from the sequence. A match within the stated mass tolerance is strong evidence that the main component is the intended molecule. Finnrick's testing guide notes that an identity test fails if the sample shows a different peptide, a blend, fragments or no peptide at all.

Some certificates confirm identity by HPLC instead, by showing that the sample's main peak elutes at the same retention time as a reference standard run on the same system. That is a valid check when a reference standard is used, but it is weaker than a mass result because different molecules can share a retention time. Our guide to HPLC versus mass spectrometry explains the difference in detail.

Reading quantity and content results

A quantity result is usually reported in mg per container, mg/ml for solutions, or as a percentage of the label claim. It is normally calculated by comparing the sample's HPLC signal with a calibration curve built from a reference standard of known concentration, not by weighing the peptide directly.

For lyophilised powders, quantity interacts with net peptide content: a vial labelled 10mg of powder can contain noticeably less than 10mg of peptide once water and counter-ions are accounted for. For pre-mixed solutions the relevant number is concentration. Both topics are covered in our guide to net peptide content versus purity.

Worked example: the Celyfe NAD+ certificate

Celyfe publishes its batch certificates in the COA library at /coa. The NAD+ Precision Pen certificate is a useful worked example because every field it contains can be checked against the product. NAD+ (nicotinamide adenine dinucleotide) is a coenzyme rather than a peptide, but the certificate is read in exactly the same way.

What the example does and does not tell you

Read honestly, an HPLC purity certificate like this one tells you that batch A26085 was tested by a named independent laboratory on a stated date, and that the batch was 99% pure by HPLC. That is the purity question answered, and the batch link makes it meaningful.

It does not, by itself, answer the questions an HPLC purity test was never designed to answer, such as endotoxin level or sterility. That is true of most purity certificates in the research market, not only Celyfe's, and it is why it is worth knowing which test answers which question before comparing suppliers. When you open any certificate, including ours, look for each of the fields above and note which of the four questions in the first table it covers.

The WOLVERINE Pen certificate (batch C26071, Analiza Białek, 99% purity by HPLC, dated 2 October 2026) follows the same format. Certificates for the GLOW and KLOW pens are being re-issued and are listed in the COA library when published.

Red flags on any COA

Any one of these is a reason to ask questions before relying on a certificate:

• No batch or lot number, or a batch number that does not match the product
• The same certificate, with the same date and batch, used for every order over many months
• No laboratory named, or a laboratory that cannot be found or does not answer verification requests
• No date, no method, or a result stated as "pass" or "high purity" with no number
• Purity reported to impossible precision (for example 99.999%) with no chromatogram
• Fonts, alignment or logos that differ within one document, a sign of editing
• A different compound, mass or label claim from the product being sold

Where Celyfe fits

Each Celyfe pen is a pre-filled, pre-mixed 3ml cartridge with an exact labelled content: NAD+ 500mg; WOLVERINE (BPC-157 15mg + TB-500 15mg); GLOW (GHK-Cu 75mg + BPC-157 15mg + TB-500 15mg); and KLOW (GLOW plus KPV 15mg). Published certificates from Analiza Białek show 99% HPLC purity for NAD+ batch A26085 and WOLVERINE batch C26071. All certificates are in the COA library at /coa, and the Strength Index at /strength-index compares the labelled mg in UK pre-filled pens.

Sources

Sources used for this guide, checked October 2026:

• Finnrick: How to read a certificate of analysis (COA), 1 March 2026 (finnrick.com/blog)
• D'Hondt M et al. Related impurities in peptide medicines. J Pharm Biomed Anal, December 2014. PMID 25044089
• Thermo Fisher Scientific: LC-UV/MS characterisation of the peptide LL-37, application note AN72818
• USP General Chapter <85> Bacterial Endotoxins Test and <71> Sterility Tests (United States Pharmacopeia)
• Celyfe COA library: NAD+ batch A26085 and WOLVERINE batch C26071, Analiza Białek, reports dated 2 October 2026 (/coa)

Research use only

Celyfe supplies research peptides for laboratory and research use only. Nothing on this page is guidance on use in humans or animals.