Question

How do I calculate percentage of a contaminant from H NMR? I know what the contaminant is but all I have is the spect.

Answer 1

indirectly he is asking % of the impurity from the original sample

this you can calculate the integration

means relative integration

lets take the any known proton integration from your sample

like integration of -CH3 group of you sample is 3 right

take integration of -CH3 of the impurity if this is also 3 then

impurity and sample is in 1:1 ratioo

where as -CH3 of the impurity is getting 1 (generally impurity integration will come very less)

the sample and inpurity ratio is 3:1

so by using integration we can find out the % of the contaminent