A supplier who responds to a discrepancy with silence — what changed since

Picking up post #12: that is the part I would want checked first.

Exaggerated claims without documentation: every compound has limits. No peptide is "100% pure" because purity is measured to finite precision. A supplier claiming implausible perfection without backing evidence is overreaching.

Rapid supplier turnover: a supplier that changes corporate structure, domain name, or contact repeatedly in short time windows raises suspicion about stability and legitimacy.

Evasion when asked: if a supplier does not clarify when asked specifically for method details, counter-ion form, or batch origin, that itself is a red flag worth documenting.

Documentation quality as a signal: a supplier that reports method identifiers, distinguishes specification from result, and states the counter-ion form is telling you something about systems behind the document. A certificate that is a number and a signature tells you less.

Patterns that reliably precede a problem: underdosing (less active material than stated, documented by independent testing), mislabelling (wrong compound, wrong strength, or wrong batch on the label), and failure to provide documentation when asked.

I read post #18 twice before replying, because I had assumed the opposite.

Anonymity: a supplier that will not disclose legal name, address, or responsible person is not operating in a way that allows accountability.

I read post #19 twice before replying, because I had assumed the opposite.

Pricing patterns: unusually low prices for what are otherwise consistent with market rates might indicate lower quality, stolen goods, or a scam. Unusually high prices without justification raise different flags.

This follows post #19 rather than contradicting it.

Inconsistency across documents: a certificate stating one purity, a website claiming another, and a supplier's verbal representation claiming a third, all on the same product, is a red flag for either incompetence or deception.

Inability to trace lots: if you ask "where was this synthesised, by whom, under what conditions" and cannot get a clear answer, that is a red flag. Traceability is not glamorous but it is foundational.

Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up.

Unresponsiveness: a supplier that does not reply to reasonable requests for documentation or clarification is showing you something about how they operate.

Picking up post #23: that is the part I would want checked first.

Safety documentation absent: a supplier that cannot provide information about sterility testing, endotoxin testing, or safety documentation when asked is raising flags.

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.

Inconsistency across documents: a certificate stating one purity, a website claiming another, and a supplier's verbal representation claiming a third, all on the same product, is a red flag for either incompetence or deception.

Patterns that reliably precede a problem: underdosing (less active material than stated, documented by independent testing), mislabelling (wrong compound, wrong strength, or wrong batch on the label), and failure to provide documentation when asked.

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.