Adding the clinical framing, because it changes how the question reads.
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: 99.2% purity, 0.0% total related substances. Clean chromatogram with single sharp peak at expected retention time. Exactly what you want to see.
DanielChem_CHI said:My vendor review relevant to certificates of analysis: ordered 3 times from my current compounder.
Third-party testing services for certificates of analysis besides Janoshik:
- Janoshik: Gold standard for peptide community, ~$150, 10-14 day turnaround
- Valitech: US-based, ISO 17025 accredited, ~$210
- Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
- ChemTox: Basic identity and purity testing, ~$120
Janoshik is the community standard but any ISO-accredited analytical lab can verify peptide identity and purity. The key is independence — don't rely solely on the vendor's own testing.
Following on from DanielChem_CHI — and this may be the naive question:
How would you tell the difference between that and the alternative explanation?
Sigma-Aldrich — Research-Grade Standards
Certified reference materials, analytical reagents, and research-grade standards for peptide verification. Trusted by laboratories worldwide.
Shop Reference Standardsquinn_sf said:Third-party testing services for certificates of analysis besides Janoshik: Janoshik: Gold standard for peptide community, ~$150, 10-14 day turnaround…
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: 14.2 minutes (consistent with semaglutide reference standard)
Peak purity: 99.0%
Related substances: 0.7% (single impurity at 8.1 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.
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