Medium effects on 33S NMR of inorganic sulphate

The effects of counter-ion binding, pH and viscosity on the line width, spin-lattice relaxation rate and chemical shift of the 33S resonance for the inorganic sulphate ion are reported. The NMR parameters are shown to be sensitive even to weak interactions, such as sodium ion binding. It is concluded that 33S NMR may be a valuable technique in the study of the inorganic chemistry of the sulphate ion. Since the sulphate resonance is sensitive to the nature of the solution, its use as a chemical shift reference should be treated with caution.