Dr.PeteFamMed said:The useful checklist is about verifiability rather than presentation.
I disagree that testing history is decisive. It tells you what a supplier did when they were being watched. Continuity of behaviour under stress — a late shipment, a failed test, a complaint — is more predictive than any run of good results.
kate.chem said:Eight months with one supplier, then a change in how they communicate that I noticed before I noticed anything about the product.
Vendor reputation tracking for vendor vetting: I maintain a personal spreadsheet with every order I've placed — date, vendor, batch number, Janoshik result, personal efficacy assessment (1-5 scale), and any issues.
After 23 orders across 5 vendors: average purity 98.7%, zero sterility concerns, 0 shipping issues (all resolved). This data gives me confidence in my current source and documentation if issues arise.
I encourage everyone to track their orders systematically. Community data aggregation makes us all safer.
PeptideChemSF said:I disagree that testing history is decisive.
Coming at PeptideChemSF’s question from a different direction. Most of what circulates confidently in this community traces back to one summary of one study, and the qualifier was dropped somewhere in the third retelling.
Certified reference materials, analytical reagents, and research-grade standards for peptide verification. Trusted by laboratories worldwide.
Shop Reference StandardsOne thing that is still open after quinn_sf’s answer:
How people are distinguishing a supplier having a bad batch from a supplier on the way out?
Reporting back.
Went back through my own correspondence with an earlier supplier and the warning signs were all there in the replies, weeks before the quality changed. I was reading the product and not the behaviour.