The determination of trace oxygen in lead by helium-3 and helium-4 activation analysis

The determination of oxygen in lead by³He and⁴He activation analysis was studied. Both methods were applied to the same material containing 0.9 μg·g^?1 of oxygen. The¹⁸F formed from oxygen was separated from matrix activities by extraction of Po with N-benzoyl-N-fenylhydroxylamine, followed by distillation of fluorosilicic acid and precipitation of lead fluorochloride (⁴He activation) or by distillation followed by precipitation (³He activation). The yield of the separation, which amounted on the average to 68%, was determined via the¹⁹F(n,⁴He)¹⁶N reaction. The coefficients of variation were 21 and 45% for⁴He and³He activation analysis, respectively, thus indicating a less homogeneous distribution of the oxygen. Nuclear interferences of sodium and fluorine were shown to be negligible.