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.
Sigma-Aldrich — Research-Grade Standards
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Shop Reference Standardswendy_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.