August 18, 2009
When you work on enough NMR datasets, eventually you will run into cases where peaks are overlapping. One approach is to apply a peak deconvolution (or fitting) algorithm in an attempt to separate out the contribution of each overlapping peak.
The 1H NMR spectrum below shows a multiplet (dd) nearly buried by a large water peak at 3.30 ppm.
Direct integration of the multiplet will give a skewed value due to the contribution from the water peak. If the multiplet at 2.87 ppm equates to 1 proton, then how many protons does the multiplet at 3.24 ppm equate to?
The calculation is shown below:
1. Total RA = Relative Area(Water) + Relative Area(dd)
= 134.85 + 13.98 + 13.54 = 162.37
2. Total DA = Deconvoluted Area(Water) + Deconvoluted Area(dd)
= 30077 + 403 = 30480
3. (Deconvoluted Area(dd) / Total DA) = (Relative Area(dd) / Total RA)
Relative Area(dd) = 403 * 162.37 / 30480 = 2.14 ~ 2 protons