Clinical perspective, offered as context rather than as advice.

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: 14.7 minutes (consistent with semaglutide reference standard)
Peak purity: 98.3%
Related substances: 0.4% (single impurity at 8.4 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.

Dr.AddMedPHL said:

Vendor quality matters when discussing certificates of analysis.

Bookmarking. The distinction being drawn above is the one nobody else makes. Adding it to my notes with a link back to this thread.

From the other side of the consultation, briefly.

I tested my certificates of analysis batch through Janoshik — 98.1% purity. That's within acceptable range for compounded peptides. Turnaround was 12 business days.

The test costs ~$133 but gives you actual HPLC chromatography data plus mass spec confirmation. For the peace of mind alone, it's worth every penny. I test every new batch from a new vendor.

lisa_labSD said:

I tested my certificates of analysis batch through Janoshik — 98.1% purity.

Can confirm. Same sequence, different timescale.

Moderator note: a couple of off-topic posts removed.