Peptides MEX / Glossary
ESI-MS: electrospray ionization and charge states
To read an ESI spectrum, distinguish ion generation from the measurement performed by the mass spectrometer.
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What electrospray contributes
ESI is an ionization technique that introduces molecules from solution into mass-spectrometric analysis. It can produce multiply charged ions. ESI names the ion source; it does not identify the analyzer or establish that LC-MS was performed.
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One molecule can generate several signals
Ion position depends on m/z and charge state. Several signal groups may therefore correspond to the same molecular species. Check whether a report presents observed m/z values or a reconstructed mass before comparing them with a theoretical mass.
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Questions about this reference
Does every ESI peak represent a different impurity?
No. Charge states and other ions derived from one molecule can generate different signals.
Sources and original reading
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