From the other side of the consultation, briefly.

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

• Janoshik: Gold standard for peptide community, ~$130, 10-14 day turnaround
• Valitech: US-based, ISO 17025 accredited, ~$220
• Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
• ChemTox: Basic identity and purity testing, ~$120

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.

JenPlateau said:

Third-party testing services for certificates of analysis besides Janoshik: Janoshik: Gold standard for peptide community, ~$130, 10-14 day turnaround…

Vendor quality matters when discussing certificates of analysis. I've tested my last 5 batches through Janoshik and purity has ranged from 97.0% to 99.2%. Consistency is key.

For anyone new: always request the COA, and consider independent verification. The $300 for a Janoshik test is worth the peace of mind.

JenPlateau said:

Third-party testing services for certificates of analysis besides Janoshik: Janoshik: Gold standard for peptide community, ~$130, 10-14 day turnaround…

My HPLC chromatogram analysis for certificates of analysis — I sent my batch to Janoshik and here's what the results showed:

Main peak retention time: 14.4 minutes (consistent with semaglutide reference standard)
Peak purity: 99.6%
Related substances: 0.8% (single impurity at 8.1 minutes — likely a synthesis intermediate)
Mass spec: m/z 4113.58 (matches expected molecular weight)

This is a clean result. The mass spec confirmation is particularly important — it proves the molecule is actually semaglutide and not a substitution.

JenPlateau said:

Third-party testing services for certificates of analysis besides Janoshik: Janoshik: Gold standard for peptide community, ~$130, 10-14 day turnaround…

This is exactly what I could not find anywhere else. Adding it to my notes with a link back to this thread.

Moderator note: the sourcing question belongs in the vendor section and has been split out. No action needed from anybody.