PharmacoVig_BOS said:

Reconstituted peptide stability data for certificates of analysis: I had Janoshik test my reconstituted vial at day 1, day 14, and day 28 stored in…

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.

PharmacoVig_BOS said:

Reconstituted peptide stability data for certificates of analysis: I had Janoshik test my reconstituted vial at day 1, day 14, and day 28 stored in…

Saving this. It is the first explanation that did not require me to already understand it.

Adding the clinical framing, because it changes how the question reads. Take it one variable at a time. Almost every unanswerable question in these threads is unanswerable because three things changed in the same fortnight, and no amount of subsequent argument can untangle them after the fact.

Happy to go further on any of that.

NurseKim_ATL said:

Almost every unanswerable question in these threads is unanswerable because three things changed in the same fortnight, and no amount of subsequent…

Mine went the same way, slower.

NurseKim_ATL said:

Almost every unanswerable question in these threads is unanswerable because three things changed in the same fortnight, and no amount of subsequent…

Coming at NurseKim_ATL’s question from a different direction. Whatever the answer turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, and invite the correction. That is slower than asserting, and it is the only version that survives being wrong.