One of the reasons why the nutation experiment mentioned above was successful is that solutions of FAAF contain a doublet-triplet admixture which allows the nutation frequencies to be compared. However, in general terms, this method would not work if the sample contained species with the same total spin quantum number. The nutation experiment requires a reference frequency. Such a reference may be obtained either by a precise calibration of the microwave power or the deliberate mixing of a species with known spin quantum number into the unknown sample. These methods are both cumbersome and prone to errors. Below we propose and deploy a more versatile method, based on ENDOR, which can be used to disentangle the spin states present in liquid solutions of multi-radical systems.