Partitioning behavior of group 1 and 2 cations in poly(ethylene glycol)-based aqueous biphasic systems

The partitioning behavior of several Group 1 and 2 cations was investigated in poly(ethylene glycol) (PEG)-based aqueous biphasic systems. All of these metal ions prefer the salt-rich phase over the PEG-rich phase with distribution ratios all well below one regardless of the system investigated. The relative salting-out ability of the individual cations can be directly correlated to their Gibbs free energy of hydration (delta G(hyd)). In addition, the relative magnitude of the distribution ratios for these metal ions can also be explained in terms of delta G(hyd).