Clinical perspective, offered as context rather than as advice.

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.

VendorMark said:

My vendor review relevant to certificates of analysis: ordered 5 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: 99.3% purity, 0.3% total related substances. Clean chromatogram with single sharp peak at expected retention time. Exactly what you want to see.

VendorMark said:

My vendor review relevant to certificates of analysis: ordered 5 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: 15.8 minutes (consistent with semaglutide reference standard)
Peak purity: 98.7%
Related substances: 0.7% (single impurity at 9.0 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.

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

What would you measure differently if you were starting again?

Moderator note: reminder that nothing in this thread is medical advice, and that clinical claims need a source. Tagging this one for the weekly digest.