Fast atom bombardment mass spectrometry of sodium and potassium oxalates—mass spectrometric evidence for the existence of (sodium–oxalate)– and (potassium–oxalate)– ion pairs in aqueous solutions

Abstract

Mass spectrometric evidence for the formation of (sodium-oxalate)^–(NaC₂O₄^–) and (potassium-oxalate)^–(KC₂O₄^–) ion pairs in aqueous solutions of potassium oxalate and sodium oxalate was obtained by analysing different concentrations of sodium and potassium oxalates in water containing 10% glycerol. The results suggest that fast atom bombardment mass spectrometry can be used to reveal the behaviour of ionic species in aqueous solutions. The KC₂O₄^– and NaC₂O₄^– ion pairs form clusters with neutral molecules of potassium oxalate and sodium oxalate and glycerol. No ion pair or cluster formation was observed when dry salts (without glycerol) were analysed. This behaviour differs from what has been observed for alkali halides under similar experimental conditions.