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    Hi guys, can someone please tell me what's the difference between these terms?

    M peak, M+ peak, M+1 peak, M+2 peak, M+3 peak

    I found these from my Cgp book: here are the pages i found them from-

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    (Original post by sienna2266)
    Hi guys, can someone please tell me what's the difference between these terms?

    M peak, M+ peak, M+1 peak, M+2 peak, M+3 peak

    I found these from my Cgp book: here are the pages i found them from-

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    Attachment 729650729652
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    The molecular ion peak is assigned M+

    Any versions of the molecule with less common isotopes which may be present can give rise to M+1, M+2, M+3 peaks

    For example the M+ peak for CH3Cl occurs at m/z = 50, in which the chlorine atom is 35Cl

    But there will be a smaller peak at m/z = 52 due to the M+2 version of the molecule in which the chlorine is 37Cl

    and for C4H10 there is an M+ signal at m/z = 58

    AND as the probability of 13C being about 1 in 100, then with 10 carbon atoms there is a 1 in 10 chance (i.e. intensity) of a signal at m/z = 59, this is an M+1 signal.
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    (Original post by charco)
    The molecular ion peak is assigned M+

    Any versions of the molecule with less common isotopes which may be present can give rise to M+1, M+2, M+3 peaks

    For example the M+ peak for CH3Cl occurs at m/z = 50, in which the chlorine atom is 35Cl

    But there will be a smaller peak at m/z = 52 due to the M+2 version of the molecule in which the chlorine is 37Cl

    and for C4H10 there is an M+ signal at m/z = 58

    AND as the probability of 13C being about 1 in 100, then with 10 carbon atoms there is a 1 in 10 chance (i.e. intensity) of a signal at m/z = 59, this is an M+1 signal.
    Thank you so so much for your reply!! This makes sense!!
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    (Original post by sienna2266)
    Thank you so so much for your reply!! This makes sense!!
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    They have called the molecular ion (labelled as such) "M"
    It is probably to avoid confusion between M+ and M+1

    The only particles detected by MS are ions, so it goes without saying that "M" is actually M+
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    (Original post by charco)
    They have called the molecular ion (labelled as such) "M"
    It is probably to avoid confusion between M+ and M+1

    The only particles detected by MS are ions, so it goes without saying that "M" is actually M+
    Thank you so much! Really appreciate your help!
 
 
 
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