If you’re sourcing research peptides for in vitro work, a Certificate of Analysis (COA) is the single most important document the supplier can hand you. It is the line between assumed quality and verified quality. Yet many researchers either skip it or don’t know what they’re looking at.
This guide walks through what a research-peptide COA actually contains, how to read one, and what red flags to watch for. Products we ship at FOR Peptides are paired with independent third-party COAs as they become available — but the principles below apply to any supplier you evaluate.
What a Certificate of Analysis Is — and Isn’t
A COA is a laboratory document confirming that a specific batch of a peptide met defined specifications when tested. It is not:
- A safety endorsement for human use (research peptides are not therapeutic agents)
- A guarantee of supplier honesty without independent verification
- Useful if the lot number on the document doesn’t match the vial you receive
A good COA is traceable, third-party, and lot-specific. Anything less is just marketing.
The Six Sections Every Peptide COA Should Have
1. Product identity
Compound name, molecular formula, molecular weight, CAS number where applicable. If the COA says only “research peptide” without naming the molecule, walk away.
2. Lot or batch number
Every production batch gets its own unique identifier. The number on the COA must match the label on your vial. This is how you connect the test result to the material you actually received.
3. Analytical method
Look for two complementary techniques:
- HPLC-UV (high-performance liquid chromatography with UV detection) at a wavelength like 220 nm — quantifies purity by peak area
- Mass spectrometry — confirms identity by matching the observed mass to the expected molecular weight
HPLC tells you how pure the peptide is. Mass spec tells you it’s the right peptide. You want both.
4. Purity result
Reported as a percentage (e.g., “99.42% by HPLC area”). For research-grade peptides, ≥99% is the target. Anything below 95% should raise questions, and anything below 90% is unsuitable for serious work.
5. Chromatogram
The graph itself. A clean COA will show a single dominant peak at the expected retention time with minimal noise. Multiple large peaks or excessive baseline noise can indicate impurities or degradation. You can browse real Janoshik chromatograms across our line on our Certificates of Analysis page.
6. Analyst and date
Real reports identify the analyst (often by name or initials) and the date the test was performed. A document that lacks both is unverifiable.
Independent vs. In-House Testing — Why It Matters
A supplier’s own lab testing their own product creates an obvious conflict of interest. The fix is independent third-party verification. We use Janoshik Analytical, an independent peptide-focused laboratory, for every production batch. Their reports are published openly on the corresponding product page — no email gate, no PDF you can’t trace.
Examples of products with their batch-level COAs available:
- BPC-157 — pentadecapeptide
- TB-500 — thymosin beta-4 fragment
- Tirzepatide (GLP-2) — dual GIP/GLP-1 incretin
- Retatrutide (GLP-3) — triple-agonist incretin
Red Flags on a Peptide COA
- Lot number missing or doesn’t match the vial. The single most common quality failure.
- Generic chromatogram reused across products. If the same graph appears for two different peptides, the document is fabricated.
- No analyst signature or date. A real lab signs and dates its reports.
- Only “passed/failed” with no numerical value. The percentage matters.
- COA available only on request, after purchase. Transparency means publishing upfront.
How to Use a COA in Your Workflow
Before ordering: scroll to the product’s COA section and verify the lot number, purity, and date. After receipt: compare the lot number on the vial to the COA you reviewed. Archive the PDF with your experimental records. If purity drops between batches, the lot-level data lets you flag it before it affects your data.
For an overview of how we test, store, and document our products, see our Quality & Testing page.
Frequently Asked Questions
How often should a research peptide be re-tested?
Every production batch should be independently tested. A COA tied to a different batch number than the vial you received tells you nothing about your material.
Does a COA expire?
The test result reflects the material at the time of testing. Storage conditions and time can degrade purity, which is why lot tracking and proper storage matter as much as the original test.
What purity should research peptides be?
≥99% HPLC purity is the working standard for serious in vitro work. Some discovery-phase studies tolerate lower purity, but published research generally cites ≥98% material.
For Research Use Only. Not for Human Consumption. The products and information referenced are intended for in vitro laboratory research only. They are not FDA-approved drugs and are not for human or veterinary use.