Inter-lab variability in peptide testing — July 2024

OK, real talk. I read all of this and my takeaway is that interpreting COAs correctly requires a chemistry background that most people here (including me) don't have. Am I wrong? I bought a vial of sema from an online vendor. They emailed me a COA. It says 98.1% purity and 5.02mg content. How do I know if the chromatogram is legitimate? I can't tell a good peak shape from a bad one. I can't evaluate whether the method was appropriate. I'm just looking at numbers and trusting the lab. Is there a simpler heuristic for non-chemists? Like — "if it comes from Janoshik with a verification number, it's probably legit"?

You're making a fair point, and I don't want to gatekeep this behind chemistry expertise. Here's a simplified decision tree for non-chemists: Step 1: Is the COA from a recognized third-party lab? - Janoshik, PeptideMeter, Vanta, or a CLIA-certified lab → proceed to Step 2 - Vendor-provided with no third-party verification → treat with skepticism Step 2: Can you verify the COA is genuine? - Use the lab's verification system (Janoshik has one) → if verified, proceed - If no verification system, contact the lab directly with the sample ID - If you can't verify it → it might be fake. Look for community members who tested the same batch. Step 3: Do the key numbers pass? - Purity ≥ 95%? → acceptable - Content within 90-110% of label? → acceptable - Identity confirmed? → acceptable - If all three pass → the product is likely what it claims to be Step 4: Any red flags? - Unidentified impurity peaks above 1%? → concerning - Content below 85% of label? → the vendor is ripping you off - No identity testing performed? → you don't actually know what it is That's it. Four steps, no chemistry degree required. If you want to go deeper, the earlier posts explain the nuances. But for a basic "should I trust this product" assessment, this covers 90% of cases.

Perfect summary. I'd add one more practical tip: save every COA you receive. Screenshot it, download the PDF, note the batch number and date. If you ever have a quality issue, that documentation is invaluable — both for reporting to the community and for holding vendors accountable. Also — if a vendor refuses to provide a COA at all, walk away. In 2026, any legitimate source should have analytical data available for their products. "Trust me, it's good" is not acceptable when you're injecting something into your body.