Disclosed herein is a method of conducting direct detection 1H solid state NMR (“ssNMR”) on a macromolecule-containing solid state formulation. The method includes conducting a 1H spin-lattice relaxation time (“T1”) experiment on the solid state formulation at various temperatures to generate a T1 value at each temperature, converting the T1 values to 1H spin-lattice relaxation rate (“R1”), and plotting R1 versus temperature to generate a relaxation rate curve for the solid state formulation. The relaxation rate curve can be analyzed to determine the molecular mobility of the macromolecule in the solid state formulation, the degree of aggregation in the solid state formulation, and/or the stability of the solid state formulation.