Mass spectrometry confirms identity, not quality

Started 27 September 2025 · 13 replies · 108 hearts · read 1.6k times

TobiasHamburg, DE · 27 September 2025

10 months ago

Something I have been sitting with: Mass spectrometry confirms identity, not quality Not looking for advice so much as other people's experience.

Evidence question. I would rather have an honest "we do not know" than a confident answer.

My question is about what a particular measurement does and does not tell you, because I think I have been reading more into it than it says.

I have read the paper and I am not sure I have understood it, and I would rather say that than pretend otherwise.

The claim I keep seeing is stated with enormous confidence and I cannot find a single primary source for it anywhere.

Thank you for reading. Careful answers welcome; confident ones I can already get elsewhere.

GwynforLlanidloes, UK

Something worth knowing: a representative certificate and a lot-specific certificate are different documents and only one of them is about your vial.

HettyCambridge, UK

My honest position is that testing narrows uncertainty rather than removing it, and anybody presenting it as removal is overselling.

8me too 8

SunilFacilitatorBirmingham, UK

Noticing a habit rather than anybody in particular: a small study cited three times is still one study, and a page can look well sourced when it is quoting itself.

PatrickLimerick, IE

Gently disagreeing with Gwynfor, or rather adding the other half of it.

What I would flag about the wider market is that a name with two published results has not been tested; a vial has.

TorKeswick, UK

Hetty has already said most of this and I want to add the one part that was different for me.

The mass check and the purity check answer different questions and I did not understand that for a year.

TasnimBradford, UK

I found that understanding what is not measured was more useful than understanding what is. The gaps are where the risk sits.

12me too 3

WystanCheltenham, UK

Something practical: I ask what the retention time and the gradient were, because a certificate without a method is very hard to interpret.

TobinCork, IE

Not a solution, just company.

PerrineStrasbourg, FR

What I would say to a newcomer is that a certificate is evidence, not a guarantee, and the distinction is the whole of this circle.

IlseMaastricht, NL

#10

Gently disagreeing with Wystan, or rather adding the other half of it.

The services people use here are Janoshik, Medutest, PeptideMeter and VendorInvestigate, and each answers a slightly different question.

EdwynNewcastle, UK

#11

Ilse, thank you for that. It gives me somewhere to start from.

What I got right was asking questions before ordering rather than after, because the answers were informative in themselves.

SunilFacilitatorBirmingham, UK

#12

Facilitator note: an honest "we do not know" is a better answer here than a confident one, and this circle exists to make that answer sayable.

NadjaBelgrade, RS

#13

Coming back to say I have now read about forty certificates and the fortieth took me two minutes, which the first one certainly did not.