Determination of boron concentration in uranium fuel samples by ICP-OES following a separation step by cation exchange resin

Abstract

The boron content of uranium fuel samples with boron concentrations in the range of 0.05–10 µg/g was determined using inductively coupled plasma optical emission spectrometry (ICP-OES) after the uranium was separated by cation exchange. The samples were dissolved in 3 M HNO3 on a hot plate at 150 °C and evaporated to near dryness. The residues were redissolved in 0.2 M HNO3 and passed through a column loaded with Dowex 50WX8-400 resin. Uranium was adsorbed on the resin, while boron was easily eluted with 0.2 M HNO3. The boron content of the effluent was determined using ICP-OES. Several strategies were employed to improve the reliability of the experimentally determined boron content. The addition of mannitol and proper control of the evaporation process were shown to be effective in preventing boron loss during sample dissolution and evaporation. The memory effect was eliminated by flushing the system with 1.5% ammonia for 30 s between successive sample runs, and the matrix match method was used to eliminate the matrix effect arising from mannitol during the ICP-OES analysis. The accuracy of the results of the analysis was determined by addition recovery tests and by comparison with the results of three Chinese certified reference materials (GBW04242, GBW04243, and GBW04232). Using the method we developed, the limit of detection for boron was as low as 0.05 µg/g in uranium fuel samples, and the relative standard deviations for 0.1–0.5 g uranium samples with 0.05–2 µg/g of boron were within 9%.