Determination of sodium-22 in rain water by using a low level β-counter

Abstract

A method has been developed for the separation from rain water of sodium-22, sufficiently radiochemically pure for it to be measured by low level β-counting. A 50-litre sample of rain water is evaporated to about 1 litre and the concentrate passed through a cation-exchange column. The sodium is eluted with 0·7 N hydrochloric acid solution. The sodium fraction is then purified, precipitated with α-methoxyphenylacetic acid, converted into sodium chloride and counted in a low background anti-coincidence β-counter.