文摘
Ions are known to concentrate in the salt-enriched phase of aqueous two-phase systems, with the only knownexception being the pertechnetate anion, TcO4-. We have discovered a second ion, nitroprusside anion (NP),which is markedly transferred from the salt phase to the polymer phase. The partitioning behavior of[Fe(CN)5NO]2- anion was investigated in ATPS formed by poly(ethylene oxide) of molar mass 3350 and35000 g mol-1, and different sulfate salts (Na2SO4, Li2SO4, and MgSO4). On the basis of a model, thenitroprusside high affinity for the macromolecular phase was attributed to an enthalpic specific interactionbetween the anion and ethylene oxide unit. Partition coefficients increased exponentially with tie-line lengthincrease, reaching values as high as 1000 and showing a relationship very dependent on the salt nature, butindependent of the polymer molar mass.