Frequency-swept solid-state S-33 nuclear magnetic resonance (NMR) spectra of a S-33-enriched organosulfur compound, [S-33]-diphenyl disulfide, are presented. The NMR spectra were acquired at extremely low magnetic fields, 0.06 and 0.10 T, which correspond to Larmor frequencies of 0.1959 and 0.3265 MHz, respectively. The quadrupole coupling constant, C-Q, and the asymmetry parameter, eta(Q), for [S-33]-diphenyl disulfide were found to be C-Q = 43.3 +/- 1.9 MHz and eta(Q) = 0.70 +/- 0.20, respectively. T-1 measurements of [S-33]-diphenyl disulfide were performed between 60 and 300 K using nuclear quadrupole resonance signals, and a compromise observation temperature was found to be 300 K. Quantum chemical calculations were performed and the results demonstrated that the quadrupole frequencies and C-Q values were highly sensitive to the changes in dihedral angles of disulfide bonds. (C) 2015 Elsevier B.V. All rights reserved.