Searching for Small Peaks in 1H Spectra - 13C Decoupling

It is not usually necessary to decouple ¹³C while observing protons as ¹³C is only 1.1% naturally abundant and ¹²C has no spin. The only thing ¹³C decoupling will do for you is collapse the very small ¹³C satellites into single resonances which (aside from a very small isotope effect) will be coincident with the proton resonances for the protons bonded to ¹²C. In certain instances however, ¹³C decoupling is desirable. Such is the case when one is looking for very small peaks in a ¹H spectrum. Below is an example of how such small peaks can be observed more easily when the ¹³C satellites are removed with decoupling. The lower trace is a conventional proton spectrum while the upper trace is the same spectrum with ¹³C decoupling. This is very useful if one is searching for small amounts of impurities underneath the ¹³C satellites of much larger resonances.

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