MikeFit_NJ said:The provenance questions are more useful than the numbers.
I am more sceptical of certificates as a category than this thread is. The document tells you about a sample somebody chose to send, at a moment in time, and nothing about the vial in your hand. Independent purchase-and-test is a different quality of evidence and everything else is inference.
newstart_MO said:I have a certificate reporting 99.2% purity and 6.1mg content on a vial sold as 5mg, and I cannot work out whether those two numbers are consistent or…
Third-party testing services for certificates of analysis besides Janoshik:
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.
PharmD_Rodriguez said:I am more sceptical of certificates as a category than this thread is.
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: 16.2 minutes (consistent with semaglutide reference standard)
Peak purity: 98.5%
Related substances: 0.8% (single impurity at 10.4 minutes — likely a synthesis intermediate)
Mass spec: m/z 4113.5 (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.
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View ResultsOne thing that is still open after paige_pharma’s answer:
Whether a purity figure and a content figure can disagree without one of them being wrong?
Closing the loop on my own question.
Purity and content being different measurements was the piece I was missing. The vial was overfilled and pure, which is a very different problem from the one I thought I had.