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Author Topic: Question about LC-MS data  (Read 1248 times)

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asihall

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Question about LC-MS data
« on: May 05, 2018, 10:42:26 AM »

Hey all! Thanks in advance for reading my question  :)

I'm writing my BSc thesis and I have a small (hopefully easy) question.

Now, I have to preface this with the fact that my PI never explained this to me and it just seemed like something he expected me to know when he handed me the datasets and at this point I'm just too afraid of asking him without sounding like a complete idiot (Either for not knowing or not asking earlier).

So I'm doing analysis on LC-MS data and I get my data as: ACID POS, ACID NEG and BASIC NEG.

Now I know the difference between the NEG and POS part, but nowhere in my analytical chemistry class did they ever talk about the ACID or BASIC parts (I even checked my book). Googling has not helped me at all  :'( .

Thanks again for reading!
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MOTOBALL

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Re: Question about LC-MS data
« Reply #1 on: May 07, 2018, 07:13:58 AM »

I assume that you have been given three tables of RT vs m/z values.
(A)One dataset will have been acquired under +ve ionization with e.g. Formic acid;
(B)One under -ve ionization, again with formic acid
(C)And one under -ve ionization with e.g. ammonium acetate or carbonate at pH ~8-9

Theoretically,
From (A) intact molecule will give [M+H]+
From (B) ".."....[M+HCOO]-
From (C)....[M-H]-

Good Luck
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asihall

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Re: Question about LC-MS data
« Reply #2 on: May 08, 2018, 01:07:32 AM »

Thank you, that makes sense :)
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