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Biochemistry 2nd year question - HARD !! watch

1. 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 ?
Attached Images

2. 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.
3. (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 ?
4. 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
5. (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 ??
6. 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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