A review of the principal interactions of nitroxides with cells suggests that if these same phenomena occur with spin adducts the result could be considerable experimental confusion and error. In particular, these could lead to differential rates of loss of spin adducts, thereby potentially invalidating conclusions on the amounts or even the types of free radicals that are trapped. In addition, shuttling of electrons between nitroxides and hydroxylamines also very significantly could alter the amounts and types of spin adducts that are observed.