Dr.EM_Chicago said:

COA red flags for certificates of analysis — here's what to look for when reviewing a Certificate of Analysis: No HPLC data: If there's no…

Vendor quality matters when discussing certificates of analysis. I've tested my last 5 batches through Janoshik and purity has ranged from 97.6% to 99.2%. Consistency is key.

For anyone new: always request the COA, and consider independent verification. The $300 for a Janoshik test is worth the peace of mind.

GraceAZ_72 said:

One addition: an unstated method makes a report close to uninterpretable.

That reframing is the part I needed.

Dr.EM_Chicago said:

COA red flags for certificates of analysis — here's what to look for when reviewing a Certificate of Analysis: No HPLC data: If there's no…

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: 15.4 minutes (consistent with semaglutide reference standard)
Peak purity: 98.4%
Related substances: 0.8% (single impurity at 9.6 minutes — likely a synthesis intermediate)
Mass spec: m/z 4113.6 (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.

wendy_avl said:

Two reports on the same product from two laboratories, four percentage points apart, and no method stated on either.

I tested my certificates of analysis batch through Janoshik — 97.3% purity. That's within acceptable range for compounded peptides. Turnaround was 8 business days.

The test costs ~$123 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.

Moderator note: two posts asking for a source have been merged into one. Please search the thread before asking again. Carry on.