O-17 AND H-1 CHEMICAL-SHIFTS OF WATER IN SOLUTIONS OF SOME AMMONIUM-SALTS - EVALUATION OF THE ANIONIC EFFECT ON THE O-17 AND H-1 CHEMICAL-SHIFTS OF WATER IN AQUEOUS-SOLUTIONS OF MINERAL ACIDS

In this paper the H-1 chemical shifts delta(H-1(av)) and the water O-1 7 chemical shifts delta((OH2)-O-17) in aqueous solutions of NH4Cl, NH4 Br, NH4I, NH4NO3, NH4ClO4, (NH4)(2)SO4, NH4H2HPO4 and (NH4)(2)HPO4 are presented and discussed. For delta((OH2)-O-17), values shift towards higher frequencies, relative to pure water delta((OH2)-O-17). NH4NO3 a nd NH4ClO4 change the water oxygen chemical shift value only slightly as compared with the other solutes. Both positive and negative delta(H -1(av)) values relative to pure water as an external reference were ob served. The strong contribution of the conjugate base anion of the aci ds to the measured O-17 and H-1 chemical shift values of water was fou nd. Using the ammonium ion as standard, the anionic effect on these pa rameters was estimated and subtracted from the measured delta((OH2)-O- 17) and delta(H-1(av)) values for the aqueous solutions of these acids .