anders_CPH said:Community-verified vendors for certificates of analysis: I maintain a spreadsheet of Janoshik-verified test results submitted by community members.
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: 99.2% purity
Day 14: 98.5% purity
Day 28: 98.4% 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.
traveltech_sara said:Agreed, and mass spec answers a question purity does not: identity.
Thank you — that is the clearest version of this I have read, and I have read a lot of them. Sending this to two other people who asked me the same thing last week.
anders_CPH said:Community-verified vendors for certificates of analysis: I maintain a spreadsheet of Janoshik-verified test results submitted by community members.
Third-party testing services for certificates of analysis besides Janoshik:
- Janoshik: Gold standard for peptide community, ~$159, 10-14 day turnaround
- Valitech: US-based, ISO 17025 accredited, ~$219
- Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
- ChemTox: Basic identity and purity testing, ~$119
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.
Sigma-Aldrich — Research-Grade Standards
Certified reference materials, analytical reagents, and research-grade standards for peptide verification. Trusted by laboratories worldwide.
Shop Reference StandardsKristenIndy 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…
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, 0.1% total related substances. Clean chromatogram with single sharp peak at expected retention time. Exactly what you want to see.
Moderator note: the sourcing question belongs in the vendor section and has been split out. Report rather than reply if it drifts again.