How to read a peptide certificate of analysis

A COA is the lab report behind a vial. Here is what purity, identity, peptide content, endotoxin and sterility results mean, and the red flags to watch for.

A certificate of analysis, or COA, is a lab report for one batch of a product. For research peptides, it is often the only independent information about what is in a vial. Reading one well will not make an unregulated product safe, but it can help you tell a thorough report from a thin one.

An example COA

Here is a BPC-157 COA listed on our BPC-157 page:

Label: 10 mg vial
Lot: BP0002, tested 30 July 2026
Net peptide content: 10.35 mg
HPLC purity: 99.61% (specification: at least 95%)
Identity: confirmed by HPLC retention-time match
Endotoxin: below 0.05 EU/mL
Sterility (PCR method): no growth
Also reported: heavy metals not detected, fentanyl screen negative
Lab: independent, stating ISO/IEC 17025 accreditation, with an online verification code

It is an example of the format, not a recommendation. Here is what each line means.

HPLC purity

HPLC (high-performance liquid chromatography) separates a sample into its parts and measures each one as it passes a detector. The result is a chart of peaks. The main peak should be the target peptide; smaller peaks are usually related impurities, such as chains missing an amino acid.

The purity figure is the main peak's share of the peptide material detected. In the example, 99.61% means almost everything the detector saw was one substance.

What purity does not tell you:

Whether that substance is the right molecule. That needs an identity test.
How much peptide is in the vial. A powder can be very pure and still weigh less than the label says.
What else is in the powder. Water, salts and counter-ions such as TFA (left over from purification) are not counted the way peptide impurities are.

A good COA includes the actual chromatogram, not just a number.

Identity: mass spectrometry or retention time

Mass spectrometry (MS, often run with HPLC as LC-MS) measures the mass of the molecules in a sample. BPC-157, for example, has a molecular weight of about 1419.5 g/mol. A matching measured mass is strong evidence the vial holds the right peptide. Look for an expected mass, an observed mass, and ideally the spectrum.

Not every COA uses MS. The example confirms identity by HPLC retention-time match: the main peak came off the column at the same time as a reference standard. That is a recognized method, but less direct than measuring mass, because different molecules can sometimes behave similarly on a column. Note which method a report used. A COA with purity but no identity test at all leaves a big question open.

Peptide content versus the label

There are two ways to describe a peptide powder's weight:

Gross weight is everything in the vial: peptide plus water, salts and counter-ions.
Net peptide content is the peptide alone.

Net content is usually noticeably lower than gross weight, so "10 mg" on a label could mean either. The COA should say which it measured. The example reports a net peptide content of 10.35 mg against a 10 mg label, about 3.5% over. Slightly above label can reflect overfilling or normal measurement variation. Well below label matters directly if you are working out concentration, for example with the reconstitution calculator, since that math assumes the label is accurate.

Endotoxin

Endotoxins are fragments of bacterial cell walls. They survive even when the bacteria are dead and can cause fever and inflammation if injected. They are measured in endotoxin units (EU), using tests described in USP chapter 85.

For approved injectable drugs, limits are product-specific and calculated from the maximum dose and body weight. A research COA usually reports a concentration without a limit; the example lists its endotoxin figure as "report result" rather than pass or fail. A low number is reassuring, but it describes only the sample tested.

Sterility

A sterility test checks a sample for living bacteria or fungi. The classic method incubates the sample and watches for growth; some labs use faster DNA-based (PCR) methods, as in the example. A pass means nothing was detected in that sample. It says nothing about contamination after the vial is opened.

Lot numbers and test dates

The lot number ties the report to one production batch. The lot on your vial should match the COA; if it does not, the report is not about your vial. The test date tells you how recent the results are, which matters because peptides can degrade over time.

COAs also vary in what they cover. The same product page lists an older BPC-157 COA from February 2026 (lot P0142). It reports 11.65 mg net peptide content and 99.105% purity, with identity by LC-MS, but states no accreditation and includes no endotoxin or sterility results. That does not mean the batch was bad; the report simply answers fewer questions.

ISO/IEC 17025 labs

ISO/IEC 17025 is the international standard for the competence of testing and calibration labs. Accreditation means an outside body has assessed the lab's methods, equipment, staff and quality system.

Two caveats. Accreditation covers a defined scope of tests, so a lab can be accredited for some methods and not others. And it is granted by accreditation bodies, not by ISO itself, so a credible claim names the body and a certificate number.

Red flags

No lot number, or a lot that does not match the vial
No test date, or a very old one
No lab name, or a lab you cannot find independently
Purity with no chromatogram
No identity test of any kind
The same COA reused across products or lots
Results that look edited, or a report the lab cannot verify when contacted

A clean COA reduces some risks. It does not make a research peptide safe, and it says nothing about whether the peptide does what it is claimed to do.

This is educational information, not medical advice.