Pep TrustHow to Read a Peptide COA (Certificate of Analysis)
You keep seeing "third-party tested" and "COA available" on vendor sites. But do you actually know what you're looking at when you open one? Here's how to read a COA in five minutes.
Most beginners don't read COAs — they glance at them. They see a document with numbers and a logo and assume it's legit. That's how people get burned. A Certificate of Analysis is your only objective proof that what's in the vial matches what's on the label. This guide shows you how to actually read one.
What is a COA?
COA stands for Certificate of Analysis. It's a lab report that verifies a peptide's identity and purity. The vendor sends a sample to a laboratory, the lab runs tests, and the lab produces this document.
The key word is independent. Ideally the vendor isn't testing their own products — that's like grading your own exam. A report from an outside, accredited lab carries far more weight than one generated in-house.
- Purity percentage
- Peptide identity (molecular weight)
- Batch / lot number
- Lab name and test date
1. Purity percentage
This is the big number everyone looks for. It tells you what percentage of the sample is actually the peptide you ordered, versus impurities or degraded material.
- What you want: 98% or higher for most peptides. 99%+ is excellent.
- What to avoid: anything below 95% is questionable. If there's no purity listed at all, walk away.
Some COAs label this "HPLC Purity," which refers to the testing method used. High-performance liquid chromatography (HPLC) is the industry standard for peptide purity testing.
Purity isn't the same as net peptide content — the fraction of the powder that's actually peptide rather than salts and water. A vial can be 99% pure yet only ~75% peptide by weight. We break this down in purity vs net peptide content.
2. Peptide identity confirmation
The COA should confirm the peptide is actually what it claims to be. This is usually done through mass spectrometry (MS), which measures molecular weight.
Look for the observed molecular weight matching the expected value for that peptide. For example, BPC-157 should come in around 1419 Da, and TB-500 around 4963 Da. If the molecular weight is way off — or missing entirely — you might not be getting what you paid for.
3. Batch or lot number
Every COA should reference a specific batch number, connecting the test results to one production run.
Why it matters: if you order a peptide and the batch number on your vial doesn't match the COA on the website, that test result might not apply to what you received. Legitimate vendors provide the COA for the exact batch you're buying — not a generic report from six months ago.
4. Lab name and test date
Check who actually ran the tests, and when.
Look for a named third-party laboratory with contact details, not a vague "internal testing facility." The date matters too: a COA from two years ago tells you nothing about the peptide sitting in inventory today. Testing within the last few months is ideal.
Red flags that should make you walk away
- No lab name listed. If they won't tell you who tested it, assume nobody did.
- Blurry or low-resolution documents. Legit COAs are clear and readable. Blurry images are often edited or fake.
- Purity conveniently at exactly 99.9% for everything. Real lab results vary. Perfect numbers across every product suggest fabrication.
- No batch number, or one that doesn't match your product.
- The vendor "does their own testing." In-house testing alone means little. Independent verification is the whole point.
Not sure if a COA is genuine?
Pep Trust reads the certificate for you and scores its authenticity and completeness — cross-checking the lab, the molecular weight, and known forgery markers, in plain language.
Verify a COA — freeHow to actually use this
Before you order from any vendor, find their COAs — most legit vendors post them publicly or send them on request. Open the COA for the specific peptide you want and check those four things: purity percentage, identity confirmation, batch number, and lab name with date.
If anything is missing or looks off, ask the vendor directly. Their response tells you a lot. Legit vendors answer quickly and transparently. Sketchy ones get defensive or dodge the question.
The bottom line
A COA doesn't guarantee a vendor is perfect. But the absence of one — or a sketchy one — guarantees you should look elsewhere. Five minutes of checking can save you from injecting mystery powder.
Research use only. This article is for scientific and educational purposes and is not medical, dosing, or investment advice. Research peptides are not approved for human or veterinary use.