Analytics · Mass spectrometry

MALDI versus ESI for a quick identity check

Analytics › Mass spectrometry high-resolution MS charge states mass error (ppm) MALDI-TOF

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r.marsdenTL3Regular5 Aug 2025#1

On the subject in the title: MALDI versus ESI for a quick identity check Working notes rather than a conclusion.

I was wrong about MALDI versus ESI in a thread last spring and I would like to correct it publicly rather than quietly.

The error was in the units, which changed the conclusion by an order of magnitude. Setting out the corrected version, and the way I now check for that class of mistake.

2 likes 12mo

to.vargaTL221 Aug 2025#2

For a compound with no reference standard in circulation, an observed mass is much more useful than an assertion of agreement with a theoretical value nobody can check.

6 likes 11mo

OTeixeiraTL3Regular2 Sep 2025#3

to.varga, post #2: For a compound with no reference standard in circulation, an observed mass is much more useful than an assertion of agreement with a theoretical value nobody can check. Go to post

Post #2 is right about the mechanism and I think understates the practical bit.

Deconvoluted spectra are easier to read and hide the evidence. Ask for the raw charge-state envelope if the identity claim matters to you.

One case, stated as one case.

16 likes in reply to #2 11mo

This topic was referenced in

Counter-ion content and its effect on measured massAnalytics › Mass spectrometry · 108 replies

This topic was closed 120 days after the last reply. Closing is automatic for quiet topics so that a settled answer does not collect new questions underneath it. If you have a follow-up, open a new topic and link back to this one — that keeps both readable and gives your question its own title.

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