Per-aqueous liquid chromatography and/or weak ion exchange chromatography as a green analytical technique for the...

The mechanism and potential applications of per-aqueous liquid chromatography (PALC) using highly aqueous non toxic and environmentally friendly mobile phases were investigated using a number of polar stationary phases primarily manufactured for hydrophilic interaction chromatography. Stationary phases were probed with a range of simple acid, neutral and basic solutes of low MW. For charged solutes, ion exchange (IEX) was the dominant retention mechanism; hydrophobic effects and possibly direct adsorption onto the polar column surface also contribute. IEX is a rather neglected mechanism and deserves further study in analytical separations, due to favourable mobile phase properties. Peak shapes were good for adenosine mononucleotides (MW ∼500) despite predictions that poor peak shapes would result from multipoint interactions. Whether PALC should be regarded as a new technique or a combination of classical mechanisms is debated.