An anion exchange technique for separation of Na and K for neutron activation analysis of W-Ti alloy

Abstract

A radiochemical neutro activation analysis procedure has been developed for the determination of sodium and potassium at parts per billion levels in high purity tungsten/titanium alloy material. The procedure involves the use of an anion exchange separation for purifying sodium and potassium activities from the alloy’s matrix activities,⁴⁶Sc and¹⁸⁷W. In addition, the use of two sequential sample loadings on the resin column prior to elution of the matrix activities has been investigated. Irradiation of 200 mg of the alloy results in a sample of nearly 1 Ci which must be handled in a remote manipulation cell. After acid dissolution of the sample, the sample solution in 1M HF was loaded onto the column. Elution of the sodium and potassium was accomplished using 40 ml of 1M HF. Similar loading and elution of the second sample was followed by the elution of matrix activities with a solution of 1M HF+6M HCl. Extensive tracer experimentation was employed to establish the possibility of retaining the matrix activities on the column while a second sample solution was processed, thus greatly increasing the throughput in terms of the number of samples analyzed per day. The detection limits of Na and K using the method developed are 4.0 ppb and 200 ppb, respectively.