james_edin said:

Vendor quality matters when discussing certificates of analysis.

Mine went the same way, slower. I had assumed I was the exception until I read this.

wendy_avl said:

My vendor review relevant to certificates of analysis: ordered 6 times from my current compounder.

Same pattern here, and in the same order.

wendy_avl said:

My vendor review relevant to certificates of analysis: ordered 6 times from my current compounder.

HPLC results interpretation for certificates of analysis: when you get your Janoshik report back, here's what the numbers mean:

• Purity %: Should be >97%. Below 95% is concerning.
• Retention time: Should match reference standard for the peptide
• Related substances: Degradation products should be <2% total
• Single impurity: No individual impurity should exceed 1%

My last batch: 99.2% purity, 0.2% total related substances. Clean chromatogram with single sharp peak at expected retention time. Exactly what you want to see.

wendy_avl said:

My vendor review relevant to certificates of analysis: ordered 6 times from my current compounder.

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: 15.7 minutes (consistent with semaglutide reference standard)
Peak purity: 99.7%
Related substances: 0.8% (single impurity at 9.5 minutes — likely a synthesis intermediate)
Mass spec: m/z 4113.6 (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.

Moderator note: reminder that nothing in this thread is medical advice, and that clinical claims need a source. No action needed from anybody.