Polarity July 18, 2011, 01:38:22 PM 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: 3543I 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 Quote Selected Last Edit: July 18, 2011, 01:39:46 PM by majah
Re: Polarity Reply #1 – July 19, 2011, 07:13:53 PM 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. Quote Selected
Re: Polarity Reply #2 – July 20, 2011, 04:26:41 AM Quote from: "majah"Hi,However, the results table still shows positive isotopes i.e. [3][M+1]+Is there a mistake?Ralf already explained how to read the annotation and I concur that for the negative mode it should be modified, like [3][M+1]- Quote from: "Ralf"[M+1]+ denotes the C12 peak for a singly charged metabolite.Here is a typo, it is the C13 peak. Quote Selected
Re: Polarity Reply #3 – July 20, 2011, 09:29:26 AM QuoteHere is a typo, it is the C13 peak.Thanks Carsten, I edited it. Quote Selected
Re: Polarity Reply #4 – July 22, 2011, 09:54:07 AM Thank you Ralf and Carsten! I get it now.Majda Quote Selected
Re: Polarity Reply #5 – August 10, 2011, 03:49:15 PM It is fixed and shows [M]- , [M+1]-, etc. for negative mode now. Quote Selected
Topic: Polarity