Hi,
I ran some ESI- data for the first time. I chose negative polarity in the settings, and didn't select any adducts under identification since there were none to choose from.
However, the results table still shows positive isotopes i.e. [3][M+1]+
Is there a mistake?
p.s. job ID is: 3543
I also realized it is very possible I am reading the adducts incorrectly. Can you please explain to me what this means, what it refers to: [3][M+1]+
Thank you.
Majda
The way it annotates isotopic peaks has nothing to do with polarity but I can see why the annotation might cause confusion.
[M]+ denotes be the C12 peak, [M+1]+ would be the C13 peak belonging to [M]+ and so on.
is an arbitrary number to indicate features that belong together in that sense, since the order of the features in the table can be changed.
The + simply shows the charge state of the metabolite.
[M+1]+ denotes the C13 peak for a singly charged metabolite.
[M+1]2+ denotes the C13 peak for a doubly charged metabolite.
We should think about modifying this type of annotation for negative mode.
Ralf already explained how to read the annotation and I concur that for the negative mode it should be modified, like [3][M+1]-
Here is a typo, it is the C13 peak.
Thanks Carsten, I edited it.
Thank you Ralf and Carsten! I get it now.
Majda
It is fixed and shows [M]- , [M+1]-, etc. for negative mode now.