TinaHashiRN said:The provenance questions are more useful than the numbers.
This answered a question I did not know how to ask. Printing the relevant bit and taking it with me.
From the other side of the consultation, briefly.
My vendor review relevant to certificates of analysis: ordered 4 times from my current compounder. Consistency has been excellent.
Shipping: 2-day priority with gel ice
Packaging: Professional, discreet, proper labeling with lot/batch numbers
Purity: 98.5% average across orders (Janoshik verified)
Customer service: Responsive within 4 hours
Price: $141/month for tirzepatide 10mg equivalent
sophie_paris said:Community-verified vendors for certificates of analysis: I maintain a spreadsheet of Janoshik-verified test results submitted by community members.
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: 14.6 minutes (consistent with semaglutide reference standard)
Peak purity: 99.6%
Related substances: 0.4% (single impurity at 8.3 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.
Certified reference materials, analytical reagents, and research-grade standards for peptide verification. Trusted by laboratories worldwide.
Shop Reference StandardsLondonLisa said:Inter-laboratory variation comes from real methodological differences, not sloppiness: which reference standard was used and how it was itself…
HPLC results interpretation for certificates of analysis: when you get your Janoshik report back, here's what the numbers mean:
My last batch: 99.5% purity, 0.1% total related substances. Clean chromatogram with single sharp peak at expected retention time. Exactly what you want to see.