Clinical perspective, offered as context rather than as advice.
HPLC results interpretation for certificates of analysis: when you get your Janoshik report back, here's what the numbers mean:
- Purity %: Should be >97%. Below 95% is concerning.
- Retention time: Should match reference standard for the peptide
- Related substances: Degradation products should be <2% total
- Single impurity: No individual impurity should exceed 1%
My last batch: 99.7% purity, 0.3% total related substances. Clean chromatogram with single sharp peak at expected retention time. Exactly what you want to see.
Following on from marcus_mpls — and this may be the naive question:
Was that from a primary source or from a summary of one?
Dr.Martinez said:HPLC results interpretation for certificates of analysis: when you get your Janoshik report back, here's what the numbers mean: Purity %: Should be…
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: 15.7 minutes (consistent with semaglutide reference standard)
Peak purity: 98.7%
Related substances: 0.5% (single impurity at 9.4 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
Certified reference materials, analytical reagents, and research-grade standards for peptide verification. Trusted by laboratories worldwide.
Shop Reference StandardsDr.Martinez said:HPLC results interpretation for certificates of analysis: when you get your Janoshik report back, here's what the numbers mean: Purity %: Should be…
Community-verified vendors for certificates of analysis: I maintain a spreadsheet of Janoshik-verified test results submitted by community members. Across 50 submitted tests:
- 82% tested at ≥98% purity
- 12% tested at 95-98% purity
- 6% tested at <95% purity (concerning)
The vendors with consistently high purity results are listed in the Vendor Directory. We update monthly based on new community submissions.