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Critical comparison of radiometric and mass spectrometric methods for the determination of radionuclides in environmental, biological and nuclear waste samples

“…The Np remained on the column is finally eluted from the column by 4-6 mol/l HCl with NH 2 OH HCl, or 4 mol/l HCl-0.1 mol/l HF. By this method, decontamination factors of 10 6 for U and 10 5 for Th, and a detection limit of 0.1 mBq have been reported [258][259].…”

“…A detection limit of 7 mBq was reported using this method [224]. For α-spectrometry, the sample is first decomposed, after removal of the 210 Po in the samples by solvent extraction or self-deposition on a silver disk [227], the sample is kept for more than 3 months for the in-growth of 210 Po, the newly generated 210 Po from 210 Pb is then selfdeposited onto a silver dick and measured by α-spectrometry using semiconductor detector.…”

“…Due to the low concentration encountered in environmental samples, a pre-concentration and completely separation from interfering radionuclides are necessary. Ion exchange, extraction chromatography and solvent extraction, are normally used for the separation of 237 Np [255][256][257][258][259][260][261][262][263] 3 , it has to be therefore reduced to Np 4+ before hydroxide precipitation. Solvent extraction using tri-n-octylphosphine oxide (TOPO) in toluene or thenoyl trifluoroacetone (TTA) in oxylene has been used to separate Np from metals, uranium, thorium and other transuranics.…”

“…Solvent extraction using tri-n-octylphosphine oxide (TOPO) in toluene or thenoyl trifluoroacetone (TTA) in oxylene has been used to separate Np from metals, uranium, thorium and other transuranics. In this step, Np is adjusted to Np 4+ and extracted into organic phase in low concentration of HNO 3 (1-2 mol/l) or high concentration of HCl (8-12 mol/l), and backextracted using high concentration of HNO 3 (8 mol/l) [259,262]. However, due to the insufficient decontamination from some elements, an anion exchange method is normally followed after solvent extraction.…”

“…Both the gamma emitting short-lived 239 Np (T½=2.35 d) and 235 Np (half-life of 396 days) may be used to trace the separation chemistry [262]. While 242 Pu is mainly used as tracer in many laboratories [259,263] because 242 Pu isotope is relatively close to 237 Np with respect to mass and ionization potential, can be obtained very pure (essentially free from 237 Np), and has a chemistry similar to that of plutonium.…”