The Measurement of Tracer Indium in Rain Samples

Abstract

A radiochemical procedure developed to measure precisely nanogram amounts of the indium tracer used in the study of circulations and rain scavenging processes in severe convective storms is described. The tracer indium collected in rainwater is normally associated with sodium, manganese and arsenic as major impurities. The method, therefore, is devised to remove arsenic as sulphide by thioacetamide precipitation followed by the extraction of indium bromide with isopropyl ether. The ether extraction separates it from sodium, manganese and lanthanum which is used as a flux monitor. The final purification of indium, from iron and other extracted impurities like gallium, in a form suitable for counting, is done by cation exchange resin separation.