How to Read a Peptide COA: What It Proves and What It Doesn’t

The story below is a composite of real experiences; details changed.

After hours at his shop, Nick Alvarez is looking at three suppliers and three “99% purity” badges. Only one of them shows its work.

Nick, 41, runs an HVAC company and has been reading peptide research since his knee scope. In his trade, nobody signs off on a system because of a sticker. You read the gauges.

So he clicks “COA” on each site. One is a PDF with a lot number and two charts. One is a stock image. One says “available on request.”

Same claim. Three very different levels of proof. Here’s how to tell them apart, so a badge never does your checking for you.

What a COA is, and isn’t

A COA is a lab’s report on one batch, called a lot. It lists the tests that were run, the results and the date.

It’s a snapshot. It tells you about that lot, tested on that day, by that lab. A COA for a different lot tells you nothing about the vial in your hand.

It also isn’t a safety approval. Research compounds are sold for laboratory research only. A clean COA doesn’t make a compound approved, or safe to use in people.

The anatomy of a COA

If the lab is accredited to ISO/IEC 17025, that’s a plus. It’s the international standard that lets testing labs show they “operate competently and generate valid results.” (ISO)

Purity isn’t the same as amount

This is the most misread line on any COA. If it has tripped you up, you’re not alone.

HPLC purity tells you whether other peptides with the wrong sequence are present. Net peptide content tells you how much of the powder is peptide at all, versus water, leftover solvents, counter-ions and salts. (AAPPTec)

The same peptide-synthesis reference notes that net peptide content can range from about 50% to 90%. It depends on the sequence and how the peptide was made and purified.

So a sample can be 99% pure and still be only 70% peptide by weight. Neither number is wrong. They answer different questions.

For what else can be in a vial besides the target peptide, read what’s in the other 1%.

What regulators noticed missing

In July 2026 the FDA reviewed several peptides for possible pharmacy compounding. Its staff looked at the certificates of analysis that came with the nominations.

For BPC-157, they said the COAs lacked specified impurity limits and testing for aggregates, bioburden or bacterial endotoxins. (FDA) For TB-500, the publicly available COA was missing tests for impurities, aggregates, microbial quality and bacterial endotoxin. (FDA)

Takeaway: a COA with only one purity number is a thin COA. The better ones show more of the list above. To see how thin the human evidence is for one popular compound, read what the BPC-157 research actually shows.

The six-point COA check

Two tabs closed

Nick closes the stock image and the “available on request.” The third PDF has a lot number, a lab name, a date, a mass spectrum and a chromatogram.

It isn’t proof that anything works. That’s not what a COA is for. It’s proof of what’s in one batch, and that’s the question it answers.

Read the lot number first, the charts second and the badge never. For more on judging the claims around these compounds, read how to evaluate a recovery claim.

Your next step: screenshot the six-point check. The next time anyone shows you a COA, start with the lot number.

---

Nick is a composite, drawn from the kinds of questions readers ask. The details are illustrative. Research compounds are sold for laboratory research only. Nothing here is medical advice or a recommendation to use any compound.