sean_dublin said:

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

Mass spectrometry confirmation for certificates of analysis: beyond HPLC purity, mass spec tells you the molecule's exact molecular weight. This confirms identity — not just purity.

Why this matters: HPLC can show you a "pure" compound, but if it's pure of the WRONG compound, purity is meaningless. Mass spec at m/z 4113.58 Da confirms it's actually semaglutide. My Janoshik report includes both HPLC and mass spec.

If your testing provider only offers HPLC, consider upgrading to include mass spec for at least your first batch from a new vendor.

sophie_paris said:

Agreed, and mass spec answers a question purity does not: identity.

Bookmarking. The distinction being drawn above is the one nobody else makes. I will report back once I have actually tried it.

sean_dublin said:

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

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

• Janoshik: Gold standard for peptide community, ~$151, 10-14 day turnaround
• Valitech: US-based, ISO 17025 accredited, ~$221
• Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
• ChemTox: Basic identity and purity testing, ~$111

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.

maya_sedona 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…

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: 16.6 minutes (consistent with semaglutide reference standard)
Peak purity: 99.8%
Related substances: 0.4% (single impurity at 10.5 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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