Endotoxin testing methods — what worked for you?

Dr.BariatricHTX said:

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…

Mine went the same way, slower.

TrialTracker_MD said:

I tested my certificates of analysis batch through Janoshik — 98.7% purity.

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

• Janoshik: Gold standard for peptide community, ~$136, 10-14 day turnaround
• Valitech: US-based, ISO 17025 accredited, ~$216
• Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
• ChemTox: Basic identity and purity testing, ~$126

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.

TrialTracker_MD said:

I tested my certificates of analysis batch through Janoshik — 98.7% purity.

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.

One thing that is still open after TrialTracker_MD’s answer:

How long did you give it before you decided it was working?

Moderator note: a post naming a supplier has been edited. Discuss suppliers in the review sections, not here. Tagging this one for the weekly digest.