jim_asheville said:They are not contradictory, they measure different things, and this is the single most common misreading of a certificate.
No disagreement with jim_asheville. One condition attached. One addition: an unstated method makes a report close to uninterpretable. "99% pure" without the technique, the standard and the conditions is a claim, not a measurement.
Dr.NateNeph 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.
jim_asheville said:They are not contradictory, they measure different things, and this is the single most common misreading of a certificate.
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.
Sigma-Aldrich — Research-Grade Standards
Certified reference materials, analytical reagents, and research-grade standards for peptide verification. Trusted by laboratories worldwide.
Shop Reference StandardsBethLabQueen 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 20 orders across 5 vendors: average purity 97.4%, 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: a post naming a supplier has been edited. Discuss suppliers in the review sections, not here. Thread quality here is what the rules are for. Keep it up.