sean_dublin said:

The provenance questions are more useful than the numbers.

Agreed, and mass spec answers a question purity does not: identity. High purity tells you one thing dominates the chromatogram, not that it is the molecule you ordered. A mass within about a dalton of expected is the identity check.

FranDenver said:

Right, and one flattering data point from a group buy is not consistency.

Bookmarking. The distinction being drawn above is the one nobody else makes. Sending this to two other people who asked me the same thing last week.

sean_dublin said:

The provenance questions are more useful than the numbers.

I am more sceptical of certificates as a category than this thread is. The document tells you about a sample somebody chose to send, at a moment in time, and nothing about the vial in your hand. Independent purchase-and-test is a different quality of evidence and everything else is inference.

Worth separating that from certificates of analysis, which this thread keeps folding into the same question. They behave differently and the advice does not transfer.

SkepticalSean said:

Six orders from the same supplier over eight months, every one independently tested, and the consistency is the part worth reporting rather than any…

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.

Moderator note: reminder that nothing in this thread is medical advice, and that clinical claims need a source. Thread quality here is what the rules are for. Keep it up.