TRADITIONAL AVERAGING OF NMR PARAMETERS IN THE FAST EXCHANGE LIMIT IS VALID

Weitekamp and co-workers have recently questioned the traditional method of averaging NMR parameters such as chemical shifts and coupling constants in the fast exchange limit because this method neglects spin energies. They have presented an alternative averaging method in which the spin energies are included in an equilibrium statistical mechanics treatment. We believe that this alternative method is not applicable to resonant measurements, such as NMR, and show that it is not in agreement with certain extant experimental data. We point out that the traditional method is correct in its neglect of spin energies and show that it is in agreement with these experimental data.