Thorium, a major element in thorium matrix, quenches uranium fluorescence when it is present above the ratio (Th/U) of 2000 in conventional pellet fluorimetry determination of uranium. A single step ‘sample digestion cum thorium fluoride precipitation’ with NH 4 HF 2 has been developed for separation of bulk thorium as hydrated thorium fluoride precipitates. Uranium in aqueous solution is extracted into ethyl acetate and stripped into pyrophosphate medium (pH ∼ 7), prior to its laser induced fluorimetry determination. Optimizations of certain parameters such as the effects of fluoride flux, mineral acid, temperature and time, stripping solution, diverse ions etc. are discussed in detail. The method has been validated by analyzing a set of synthetic mixtures and certified reference materials of rock samples such as SY-2, SY-3, GSP-2, NKT-1 and CG-2 doped with a large excess of thorium. This method has been applied for the determination of microgram to nanogram uranium in thorium rich rocks and synthetic nuclear grade ThO 2 with high degree of accuracy and precision. This is the improvement of the existing method which involves two liquid-liquid solvent extraction separation of thorium and uranium using the chelating agent 2,3-dihydroxynaphthalene at the different pH, compared to one solvent extraction separation of uranium in the present method, because separation of thorium by precipitation as its fluoride has already been carried out during sample digestion step itself. The proposed method involving ammonium hydrogen fluoride in combination with laser induced fluorimetry is simple, rapid, cost effective and more eco-friendly.

中文翻译：

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NH4HF2析出氟分离separation后，通过激光诱导荧光法测定th基体中的痕量铀

conventional是th基体中的主要元素，在常规的颗粒荧光法测定铀中，当铀的比率（Th / U）大于2000时，quench淬灭铀荧光。已开发出一种使用NH 4 HF 2的“样品消解兼氟化fluoride沉淀”的单一步骤，用于分离水合氟化or沉淀物中的大量th。将水溶液中的铀萃取到乙酸乙酯中，然后汽提到焦磷酸盐培养基（pH约为7）中，然后进行激光诱导荧光测定。详细讨论了某些参数的优化，例如氟化物通量，无机酸，温度和时间，汽提溶液，各种离子等的影响。该方法已通过分析一组岩石样品的合成混合物和经认证的参考物质（例如SY-2，SY-3，GSP-2，NKT-1和CG-2掺有大量的th。该方法已用于高精度，高准确度的富rocks岩石和合成核级ThO 2中微克至纳克铀的测定。这是对现有方法的改进，该方法涉及在不同pH下使用螯合剂2,3-二羟基萘两次液-液溶剂萃取分离and和铀，与本方法中一种溶剂萃取分离铀相比，因为分离由于沉淀中的氟化物已经在样品消解步骤本身中进行过，因此不会析出th。所提出的将氟化氢铵与激光诱导荧光法结合使用的方法简便，快速，具有成本效益并且更加环保。该方法已用于高精度，高准确度的富rocks岩石和合成核级ThO 2中微克至纳克铀的测定。这是对现有方法的改进，该方法涉及在不同pH下使用螯合剂2,3-二羟基萘两次液-液溶剂萃取分离and和铀，与本方法中一种溶剂萃取分离铀相比，因为分离由于沉淀中的氟化物已经在样品消解步骤本身中进行过，因此不会析出th。所提出的将氟化氢铵与激光诱导荧光法结合使用的方法简便，快速，具有成本效益并且更加环保。该方法已用于高精度，高准确度的富rocks岩石和合成核级ThO 2中微克至纳克铀的测定。这是对现有方法的改进，该方法涉及在不同pH下使用螯合剂2,3-二羟基萘两次液-液溶剂萃取分离and和铀，与本方法中一种溶剂萃取分离铀相比，因为分离由于沉淀中的氟化物已经在样品消解步骤本身中进行过，因此不会析出th。所提出的将氟化氢铵与激光诱导荧光法结合使用的方法简便，快速，具有成本效益并且更加环保。