Polarographic determination of caesium in the presence of other alkali metals based on interaction with the cinnamaldehyde radical anion

Abstract

In this determination of caesium the wave i_M, corresponding to the reduction of a species formed by interaction of a cinnamaldehyde radical anion with alkali-metal ions, is measured. This wave appears in 0·1 M lithium hydroxide solutions between the first two one-electron reduction steps of cinnamaldehyde.

The height of this wave i_M increases with increasing alkali-metal concentration, and is most sensitive to caesium, which can be determined in the range 0·003 M to 0·1 M, in the presence of less than 0·03 M rubidium, 0·05 M potassium and 0·1 M sodium, to within an accuracy of 5 per cent. The only observed interference was from short-chain tetra-alkyl ammonium cations.