Radiochromatography of Alkali Ions

Abstract

IN their recent communication¹, Modreanu, Fise¹ and Carpov state “only three mixtures of solvents seem to have been proposed to accomplish the chromatographic separation of potassium, rubidium and cæsium”. These methods being “tedious”, they use nitrobenzene saturated with water as solvent for the separation of potassium, rubidium and cæsium spotted as picrates on Whatman paper No. 4. I have, however, shown that an even larger range of alkali ions, namely, lithium, sodium, potassium, rubidium and cæsium, could be separated employing a markedly simpler procedure². This merely used acid-washed asbestos paper and dilute hydrochloric acid as solvent. The use of radioisotopes as tracers, namely, sodium-22, potassium-42, rubidium-86, cæsium-137, both expedited and simplified the analysis of the chromatogram. In the case of lithium, however, a Perkin-Elmer flame photometer was used to determine its répartition. The following R_F values were obtained for tracer to milligram concentrations of the different alkali ions with 0.1 N hydrochloric acid as solvent on bands of asbestos paper 12 mm. wide, 25 cm. long and 0.2 mm. thick.