Neutron activation analysis for sodium traces in magnesium

When sodium traces are determined in magnesium matrices by neutron activation analysis, the reaction ²⁴Mg(n,p)²⁴Na interferes by simulating spurious sodium concentrations (about 400–500 p.p.m. for usual irradiation positions in the RS 1 water-pool reactor). A preliminary separation of the sodium traces from the bulk of the matrix by electrudeposition on a mercury cathode and recovery in water by amalgam decomposition, prevented the fast-neutron effects. Electrolysis for 4 h gave almost quantitative recovery of sodium (93±5%) and satisfactory decontamination factors for magnesium (1.5 to 5. 10³). The method is limited by the blank correction (14 μg Na with a glass electrolysis cell). Some results for magnesium samples with both destructive and non-destructive techniques are reported.