**A COA is only as good as the tests it includes and the lab that ran them. Here's exactly what to look for — and what to run from.**
Why this matters
Every reputable research peptide supplier publishes COAs. Most people glance at the purity number and move on. That's a mistake.
A COA that shows 99.2% purity but only ran HPLC tells you the sample is pure — but not *what it is*. A COA that only ran mass spectrometry tells you the molecule identity — but not whether it's contaminated with manufacturing byproducts.
You need both. Every time.
The two essential tests
Test 1: HPLC (High-Performance Liquid Chromatography)
**What it measures:** Purity — what percentage of your sample is the target peptide versus everything else.
**How it works:** The sample is dissolved in solvent and pumped through a chromatography column. Different molecules interact with the column material differently, so they separate over time. A UV detector plots the results as a chromatogram — a graph with peaks.
**How to read it:** - The big peak = your target peptide - Small peaks = impurities - Purity = (area of target peak ÷ total area of all peaks) × 100 - **Research grade: 99%+ is the standard. Below 98% is unacceptable for serious work.**
**What HPLC does NOT tell you:** Whether the big peak is actually the peptide you ordered. It could be 99.2% pure... of the wrong molecule.
Test 2: Mass Spectrometry (MS)
**What it measures:** Molecular identity — whether the peptide has the correct molecular weight.
**How it works:** The sample is ionized and accelerated through a magnetic field. Molecules deflect at different rates based on their mass-to-charge ratio (m/z). The detector reports the observed mass.
**How to read it:** - **Observed mass** should match **theoretical mass** within ±1 Da - Example: BPC-157 theoretical mass = 1,419.53 Da. If the COA shows observed mass of 1,419.7 Da, that's a match - If the observed mass is off by more than 1 Da, the peptide is either wrong or degraded
**Reference molecular weights for common research peptides:**
| Peptide | Molecular Weight (Da) | |---------|----------------------| | BPC-157 | ~1,419 | | TB-500 (Tβ4 fragment) | ~4,345 | | Tirzepatide | ~4,814 | | Retatrutide | ~4,731 | | Semaglutide | ~4,114 |
The 6-point COA checklist
Before accepting any COA as legitimate, verify all six:
1. Lab independence The COA must come from a **third-party lab** — not the supplier's own facility. Legitimate independent labs include Kovera Labs, Janoshik Analytical, and Anresco. The document should show the lab's name, logo, address, and contact information.
**Red flag:** "In-house testing" or no lab identity at all.
2. Batch number match The batch/lot number on the COA must match the number printed on your vial label. If they don't match, the COA is for a different production run — it tells you nothing about what's in your hand.
**Red flag:** No batch number on the COA, or a generic COA that doesn't reference a specific lot.
3. Test date recency COAs should be dated within the last 12 months. Older documents may not reflect the supplier's current manufacturing quality.
**Red flag:** COA dated more than 12 months ago, or no date at all.
4. HPLC purity ≥ 99% Look for the integrated peak area percentage. 99%+ is research grade. 99.5%+ is excellent. Below 98% means the synthesis was poor or the purification was inadequate.
**Red flag:** Purity reported without specifying the analytical method, or purity that changes significantly between HPLC runs.
5. Mass spec identity confirmed Observed mass within ±1 Da of theoretical mass. Both numbers should be printed on the COA.
**Red flag:** Mass spec section is missing entirely. This means identity was never verified.
6. No flagged impurities Common impurities to watch for: - **Truncated sequences** — missing amino acids from poor synthesis - **Residual solvents** — TFA (trifluoroacetic acid), acetonitrile - **Water content** — normal in small amounts, excessive means poor lyophilization
Small amounts are expected. Large amounts suggest quality control failures in synthesis or purification.
The red flag hall of shame
Any one of these is a reason to question the supplier:
- ❌ **"In-house tested"** — no independent verification
- ❌ **Mass spec missing** — purity without identity
- ❌ **HPLC missing** — identity without purity
- ❌ **No batch number** — can't verify the COA applies to your product
- ❌ **Batch number doesn't match your vial** — wrong COA
- ❌ **Test date older than 12 months** — stale data
- ❌ **Stock photo or generic image** — not a real COA
- ❌ **No lab name or contact information** — untraceable
- ❌ **Purity reported to unusual precision** (e.g., "99.9873%") — HPLC doesn't give that many significant figures
Why third-party testing exists
The peptide research market is largely unregulated. There is no FDA pre-approval for research-grade compounds. Quality control is self-imposed — or it isn't imposed at all.
Third-party testing exists because the alternative is trusting the supplier's word. And in a market where: - Synthetic peptides can be mislabeled - Purity claims can be fabricated - The wrong amino acid sequence can produce a different compound entirely
...independent verification is the only reliable signal.
What we publish
Every batch on this site is tested by an independent laboratory. Both HPLC and mass spectrometry are run. COAs are published with batch numbers that match vial labels. Test dates are current.
This isn't a competitive advantage — it should be the industry standard. Until it is, checking the COA yourself is the best protection available.
*This article is for educational and research purposes only. The compounds discussed are sold for research use. Not for human consumption. No therapeutic claims are made.*