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    Hey,

    Ive been having so much trouble with this question i came across from a past paper. The question is attached. I am guessing its a theoretical question as the data is not there to figure out a numerical value.

    Anyone have any ideas on how to solve it ?
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    Using P1 and P2 as labeled and assuming that those peaks correspond to multiply charged instances of the intact molecule being analysed:

    m=mass of molecule
    z=charge of ion

    m/z = peak value.

    In this case you have m/10 = p1, and m/11 = p2, and theoretically you would read p1 and p2 of the spectrum. In this case, simply manipulate the equations to get m = 10p1 = 11p2, and verify that these give the same result.

    This looks about right because you can see the spacing between the peaks decrease as z increases up to 20. You get the same pattern if you plot the values of 1/x where x is an integer on a number line and see the points become closer spaced as x increases.
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    (Original post by Blocker)
    Using P1 and P2 as labeled and assuming that those peaks correspond to multiply charged instances of the intact molecule being analysed:

    m=mass of molecule
    z=charge of ion

    m/z = peak value.

    In this case you have m/10 = p1, and m/11 = p2, and theoretically you would read p1 and p2 of the spectrum. In this case, simply manipulate the equations to get m = 10p1 = 11p2, and verify that these give the same result.

    This looks about right because you can see the spacing between the peaks decrease as z increases up to 20. You get the same pattern if you plot the values of 1/x where x is an integer on a number line and see the points become closer spaced as x increases.
    Thanks for this it makes sense, just one thing.. when you said that ''m/10 = p1, and m/11 = p2'' did you mean m/10 = p2, and m/11 = p1 ?

    Also, if there a reference that i can look at for this question because i haven't managed to find any... Thanks

    btw do you do biochem ?
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    Yes, yes i did

    As for references, afriad not. Just google mass spectrometry and try to find a decently laidout web page. For singly charged stuff chemguide should be quite useful

    As for the last question, i do normal chem
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    (Original post by Blocker)
    Yes, yes i did

    As for references, afriad not. Just google mass spectrometry and try to find a decently laidout web page. For singly charged stuff chemguide should be quite useful

    As for the last question, i do normal chem
    Hey, do you also know why its an advantage of having multiple charges ??
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    As this is biochem im going to presume these are tactics mostly related to analysing big proteins and stuff. So im only guessing here, since i tend to stick to the small stuff. But a quick google informs me that having the multiple charge data allows the generation of a profile displaying the average mass (averaging over all the different m/z values should improve accuracy) which also tends to show impurities up as well (salt adducts such as sodium, potassium etc).

    But i may be wrong
 
 
 
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