Dr.EM_Chicago said:

Vendor quality matters when discussing certificates of analysis.

Third-party testing services for certificates of analysis besides Janoshik:

• Janoshik: Gold standard for peptide community, ~$127, 10-14 day turnaround
• Valitech: US-based, ISO 17025 accredited, ~$217
• Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
• ChemTox: Basic identity and purity testing, ~$127

Janoshik is the community standard but any ISO-accredited analytical lab can verify peptide identity and purity. The key is independence — don't rely solely on the vendor's own testing.

A narrower follow-up, since the general answer is now clear:

What a vetting checklist should actually contain, as opposed to a list of things that are easy to fake?

stefan_berlin said:

Third-party testing services for certificates of analysis besides Janoshik: Janoshik: Gold standard for peptide community, ~$127, 10-14 day turnaround…

Mass spectrometry confirmation for certificates of analysis: beyond HPLC purity, mass spec tells you the molecule's exact molecular weight. This confirms identity — not just purity.

Why this matters: HPLC can show you a "pure" compound, but if it's pure of the WRONG compound, purity is meaningless. Mass spec at m/z 4113.58 Da confirms it's actually semaglutide. My Janoshik report includes both HPLC and mass spec.

If your testing provider only offers HPLC, consider upgrading to include mass spec for at least your first batch from a new vendor.

stefan_berlin said:

Third-party testing services for certificates of analysis besides Janoshik: Janoshik: Gold standard for peptide community, ~$127, 10-14 day turnaround…

COA red flags for certificates of analysis — here's what to look for when reviewing a Certificate of Analysis:

• No HPLC data: If there's no chromatography graph, it's not a real COA
• Exact 100% purity: Suspicious — real testing always shows slight variation
• No batch number: Can't trace back to specific production
• No endotoxin testing: For injectables, this is essential
• Template looks like it was made in Word: Professional labs have standardized formats

I have seen fake COAs that are literally photoshopped. Always verify independently if possible.

Reporting back.

Went back through my own correspondence with an earlier supplier and the warning signs were all there in the replies, weeks before the quality changed. I was reading the product and not the behaviour.