rachel_ABQ said:I tested my certificates of analysis batch through Janoshik — 97.6% purity.
Reconstituted peptide stability data for certificates of analysis: I had Janoshik test my reconstituted vial at day 1, day 14, and day 28 stored in the refrigerator.
Day 1: 99.4% purity
Day 14: 98.2% purity
Day 28: 99.2% purity
Minimal degradation over 28 days when properly refrigerated. This confirms the standard 28-day beyond-use date is appropriate. Beyond 28 days, I'd reconstitute a fresh vial to be safe.
MikeKY_noInsulin said:One addition: an unstated method makes a report close to uninterpretable.
Bookmarking. The distinction being drawn above is the one nobody else makes.
rachel_ABQ said:I tested my certificates of analysis batch through Janoshik — 97.6% purity.
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: 16.2 minutes (consistent with semaglutide reference standard)
Peak purity: 99.5%
Related substances: 0.6% (single impurity at 10.7 minutes — likely a synthesis intermediate)
Mass spec: m/z 4113.5 (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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View ResultsDr.RheumBOS said:I have a certificate reporting 99.2% purity and 6.1mg content on a vial sold as 5mg, and I cannot work out whether those two numbers are consistent or…
Third-party testing services for certificates of analysis besides Janoshik:
- Janoshik: Gold standard for peptide community, ~$145, 10-14 day turnaround
- Valitech: US-based, ISO 17025 accredited, ~$205
- Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
- ChemTox: Basic identity and purity testing, ~$125
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.
Moderator note: good thread. Keeping it here rather than moving it, because the question is general enough to be useful. Carry on.