Separation and Identification of Alkali Metals on Paper Chromatograms

Abstract

THE alkali metals do not readily lend themselves to detection on paper chromatograms by general or specific spot reagents, except in high concentration, as, for example, using hexanitro-diphenylamine as a spray reagent for the detection of potassium. A method has been developed which utilizes the production of an insoluble coloured precipitate when potassium, cæsium, rubidium and the ammonium ion are treated with a solution of sodium cobalti-nitrite. The paper chromatogram is run in the usual fashion and dried. It is then either heavily sprayed with or soaked in a solution of cobaltinitrite. The solution of Kramer and Tisdall¹ or a freshly prepared 10 per cent aqueous solution of solid sodium cobaltinitrite in 5 per cent acetic acid may be employed.