Determination of traces of Np-237 in environmental samples by ICP-MS afterseparation using TOA extraction chromatography

A simple, rapid, cost-efficient, and robust method for separation of Np-237 with an extraction chromatographic column (TOA: tri-n-octylamine on Teflon powder) is outlined in detail and further improved for direct ICP-MS analy sis. The column efficiently retained Np-237 in 2 mol L-1 HNO3 medium and al l of the Np-237 was easily eluted with 0.02 mol L-1 oxalic acid in 0.16 mol L-1 HNO3 at 95 degreesC. The separated solutions were free from most matri x elements and were aspirated into the ICP-MS directly. The decontamination factor for U-238 is more than 10(4). The instrumental detection limit for Np-237 was 0.46 pg mL(-1), which corresponds to 1.2 x 10(-5) Bq mL(-1). The method is more rapid than traditional radiometric techniques. It is also c onsidered to be more suitable for environmental monitoring than existing me thods based on TOA.