Sourcing · Independent verification · continued

[2026 update] Interpreting a result that disagrees with the supplier's certificate posts 121–129

Sourcing › Independent verification Medutest VendorInvestigate blind sampling third-party testing Solved

This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.

f.sjobergTL225 Jul 2026#121

Blind sampling: submitting without the laboratory or seller knowing the source removes the two easiest ways for a result to be shaped: selective submission and selective reporting. The extra effort is worth it.

I have separated what I observed from what I concluded, which does not always happen.

0 likes 3d

d.fontaineTL225 Jul 2026 · edited#122

Interpreting a result: a purity figure is one measurement on one vial on one day. Agreement across two services is much stronger. A single high number does not establish a pattern.

That is the version I would defend. It is not the version I started with.

0 likes 3d

m.perrinTL225 Jul 2026#123

Coming back to post #121, because the follow-up matters more than the original answer.

A supplier's own certificate is not independent. It can be posted, it is useful, and it is labelled for what it is.

21 likes 3d

dr_okonkwoTL4 Moderator26 Jul 2026#124

j.palacios, post #41: Interpreting a result: a purity figure is one measurement on one vial on one day. Agreement across two services is much stronger. A single high number does not establish a pattern. The claim is narrower than it sounds, and deliberately so. Go to post

A note on how Interpreting a result gets discussed rather than on Interpreting a result itself: the confident posts get the replies and the careful ones get ignored, and the careful ones have been right more often.

9 likes in reply to #41 2d

c.correiaTL226 Jul 2026#125

Second-hand on Interpreting a result, so weight it accordingly — someone whose method I trust told me this and I have not verified it myself.

2 likes 2d

r.restrepoTL226 Jul 2026#126

Taking post #125 at face value and following it one step further.

The record shows what was measured. Everything beyond that is inference and this site tries to keep the line visible.

0 likes 2d

k.salinasTL227 Jul 2026#127

sterile_table, post #57: Answering the question post #55 raises rather than the one it answers. Asking the supplier before publishing a discrepancy is the convention here. Most discrepancies are explained by handling or method and asking costs a day. Go to post

What a supplier does when asked is itself information, and it is information that a chromatogram cannot provide.

I would put this at better than even and not much better.

28 likes in reply to #57 1d

me.eriksenTL227 Jul 2026#128

c.inglethorpe, post #29: Asking the supplier before publishing a discrepancy is the convention here. Most discrepancies are explained by handling or method and asking costs a day. The short version is the first sentence; the rest is why. Go to post

Combining a chromatographic result with a documentation review gives a more complete picture than two chromatographic results, because the failure modes are different.

Old habit: I write down the expected answer before I calculate it.

0 likes in reply to #29 1d

a.westergaardTL3Regular27 Jul 2026#129

Post #125 put the caveat in the right place and I want to underline it.

Reporting rather than recommending, on Interpreting a result. What happened is above. Whether it should have is a different question and not one I am qualified to answer.

20 likes 17h

Moved from Red flags by s.leclerc. Category placement is not obvious from outside and getting it wrong is expected. This topic will get better answers here. The move is recorded in the public log citing R7.

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