A Certificate of Analysis is the proof behind a vendor's purity claim. Without it, '99% pure' is just marketing. Here's what to actually look for on a real COA.
1. Assay (HPLC)
The most important number. Reverse-phase HPLC separates the target peptide from byproducts and reports how much of the vial's mass is actually the intended sequence. 99.0% is the floor of research-grade.
2. Mass spectrometry confirmation
Confirms the peptide's molecular weight matches the expected sequence. Catches synthesis errors a pure-but-wrong batch can hide.
3. Moisture
Karl-Fischer titration measures residual water. Under 5% is acceptable; under 2% is excellent. High moisture accelerates degradation in storage.
4. Endotoxin (LAL)
Bacterial endotoxins are pyrogenic. The Limulus Amebocyte Lysate test measures EU/mg. Anything ≤ 5 EU/mg is acceptable for in-vitro research; ≤ 0.5 EU/mg is pharmaceutical-grade.
5. Sterility
A pass/fail on microbial contamination.
6. The lab issuing the COA
Independent third-party labs accredited to ISO 17025 carry far more weight than in-house COAs. Look for the accreditation logo and the name of the lab, not just a signature.
Every batch we ship comes with an independent COA from Veridis Analytical Labs (UK, ISO 17025). View any of them on our Lab Reports page.