Polymorphism in Sulfanilamide: N-14 Nuclear Quadrupole Resonance Study

To demonstrate the selectivity of N-14 nuclear quadrupole resonance (N-14 NQR) spectroscopy in chemistry and pharmacy, a study of sulfanilamide polymorphism was undertaken. We studied 3 known polymorphs of sulfanilamide by N-14 NQR. We found at room temperature 2 sets of 3 N-14 NQR transition frequencies, corresponding to 2 different nitrogen sites in the crystal structure for each of 3 polymorphs. We measured the temperature dependence of all quadrupole frequencies nthorn, nu(+),nu(-). In each set, only 1 of the 3 N-14 NQR frequencies is enough to characterize the polymorph. Spin-lattice relaxation time (T-1) measurement is supplemental information. We also measured the transition temperature between polymorphs and estimated the ratio of polymorphs after thermal treatment of sample. (c) 2019 American Pharmacists Association (R). Published by Elsevier Inc. All rights reserved.