How to Read a Peptide COA
A Certificate of Analysis (COA) is your primary tool for verifying peptide quality. This tutorial teaches you to read and verify COAs like an expert.
Why This Matters
A COA is only valuable if you can verify it's legitimate and understand what it's telling you. Many low-quality vendors provide fake or misleading COAs.
What is a COA?
A Certificate of Analysis is a document that provides:
- Identity confirmation - Proof the substance is what it claims to be
- Purity measurement - Percentage of the desired compound vs impurities
- Batch information - Links testing to a specific production run
- Test methodology - How the testing was performed
Key Components of a Legitimate COA
1. Header Information
The top of any COA should contain:
| Element | What to Look For | Red Flag |
|---|---|---|
| Lab Name | Named, searchable laboratory | "Lab Services Inc." or generic names |
| Test Date | Recent (within 6-12 months) | Very old dates or no date |
| Batch/Lot # | Unique identifier | Same number on multiple COAs |
| Product Name | Exact peptide name/sequence | Vague or incorrect naming |
| Quantity Tested | Specific amount noted | Missing quantity information |
2. HPLC Results (High-Performance Liquid Chromatography)
HPLC measures purity by separating compounds and measuring their proportions.
Understanding the Chromatogram
What you're looking at: A graph showing peaks, where:
- X-axis (Time): When compounds eluted from the column
- Y-axis (Signal): Amount of each compound detected
- Main Peak: Should be your target peptide
- Small Peaks: Impurities (should be minimal)
Key HPLC Numbers
- Purity %: Should be 98%+ for most research peptides
- Retention Time: When the main compound eluted (in minutes)
- Peak Area %: Proportion of total signal from main peak
Good COA: Shows a clean chromatogram with one dominant peak (>98% area) and minimal noise or secondary peaks.
Bad Sign: Multiple large peaks, purity below 95%, or a noisy baseline indicating contamination.
3. Mass Spectrometry Results
Mass spec confirms the identity of the peptide by measuring its molecular weight.
What to Check
- Expected MW: The theoretical molecular weight of the peptide
- Observed MW: What the test actually measured
- Acceptable Variance: Should be within ±1-2 Daltons
Common Peptide Molecular Weights
| Peptide | Expected MW (Da) |
|---|---|
| BPC-157 | 1419.53 |
| TB-500 | 4963.44 |
| Ipamorelin | 711.85 |
| CJC-1295 (no DAC) | 3367.97 |
| GHK-Cu | 403.92 |
| Semaglutide | 4113.58 |
Pro Tip: You can verify expected molecular weights on PubChem or by searching "[peptide name] molecular weight."
4. Additional Quality Markers
Some COAs include additional useful information:
- Amino Acid Analysis (AAA): Confirms sequence composition
- Endotoxin Testing: Important for injectable peptides
- Sterility Testing: If claimed to be sterile
- Water Content: Measured by Karl Fischer titration
How to Spot a Fake COA
Common Red Flags
- Template COAs: Same document used for multiple products with only the name changed
- Generic Lab Names: "Quality Testing Services" with no verifiable contact info
- Perfect Numbers: Exactly 99.00% purity is suspiciously round
- Missing Chromatogram: COA without actual HPLC graph image
- Date Inconsistencies: Test date after sell date, or very old tests
- Wrong Molecular Weight: Observed MW doesn't match expected
- Photoshop Artifacts: Visible editing, misaligned text, different fonts
- Same Batch Number: Multiple products showing identical batch numbers
Verification Steps
- Request before purchase: Ask for the specific batch COA you'll receive
- Search the lab: Verify the testing laboratory exists and is reputable
- Contact the lab: Some labs will verify if a COA is authentic
- Compare to references: Check molecular weights against databases
- Consider independent testing: For large purchases, get your own testing done
Independent Testing Options
For maximum confidence, especially with large orders, consider third-party testing:
- University Labs: Some chemistry departments offer testing services
- Commercial Labs: Services like Janoshik, Colmaric, or Valisure
- Cost: Typically $50-150 per test
- When to test: New vendor, bulk order, or if anything seems off
Remember: A COA is only as trustworthy as its source. Even a perfect-looking COA from an unknown lab provides limited assurance. Prioritize vendors with independently verifiable testing from established laboratories.