From the other side of the consultation, briefly.
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: 99.3% purity, 0.3% total related substances. Clean chromatogram with single sharp peak at expected retention time. Exactly what you want to see.
Clinical perspective, offered as context rather than as advice.
Third-party testing services for certificates of analysis besides Janoshik:
- Janoshik: Gold standard for peptide community, ~$153, 10-14 day turnaround
- Valitech: US-based, ISO 17025 accredited, ~$223
- Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
- ChemTox: Basic identity and purity testing, ~$123
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.
roxy_nash said:Third-party testing services for certificates of analysis besides Janoshik: Janoshik: Gold standard for peptide community, ~$153, 10-14 day turnaround…
This is my experience too, for whatever a second data point is worth. Posting only so the count is not one.
Sigma-Aldrich — Research-Grade Standards
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Shop Reference Standardsroxy_nash said:Third-party testing services for certificates of analysis besides Janoshik: Janoshik: Gold standard for peptide community, ~$153, 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: 14.4 minutes (consistent with semaglutide reference standard)
Peak purity: 99.6%
Related substances: 0.4% (single impurity at 8.7 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.