Requirements: 

Acid washed asbestos paper, dil. HCl as solvent, Radiotracer solution of ²²Na (t_1/2 = 2.6 y), ⁴²K (t_1/2 = 12.36 h), ⁸⁶Rb (t_1/2 = 18.6 d) and ¹³⁷Cs (t_1/2 = 30.1y), Well type NaI(Tl) scintillation gamma ray spectrometer.

Procedure:

Asbestos paper strip of 40 cm×3cm was taken and starting 3 cm from one end, lines were drawn using pencil at an interval of half cm up to 30 cm. each line was numbered. The glass chamber is filled with dil HCl up to a height of 5cm. Spotting was done on the strip using radiotracers at about 3 cm from one end in the centre. It was hung such that one half of its bottom remains dipped in solvent. The solvent starts rising till it stops rising any further in about an hour. The paper is removed from the chamber and dried in a drying chamber. Strips are cut along the lines, kept in a polythene bag and each strip is counted for 50 seconds in the well type scintillation counter. The activity of the strips (Y-axis) is plotted against the strip number (X-axis). Peaks observed for individual radioisotopes are used for calculating R_f values. Following values were obtained for individual alkali metal cations.

Na⁺     K⁺       Rb+    Cs⁺

0.86     0.77     0.72     0.45

In an unique application speciation studies of sulphur, S^2- , SO₃^2-, and SO₄^2- have been identified by using ³⁵S (t_1/2 = 87.2 d) as tracer and GM counting system.