共沉淀分离-ICP-MS法测定地质样品中痕量铀

Coprecipitated separation—determination of trace U(Ⅳ) and U(Ⅵ) in the geological samples by ICP-MS

建立了电感耦合等离子体质谱法（ICP-MS）测定痕量U价态分析方法。利用邻菲罗啉掩蔽Fe（Ⅱ）防止U（Ⅵ）被还原,硫酸羟胺防止U（Ⅳ）被氧化,HF溶解硅酸盐并与U（Ⅳ）形成UF4沉淀,硫酸铈铵和CaCO_3作为共沉淀剂混合载体,沉淀后离心分离。分别溶解上清液和沉淀,用ICP-MS进行测定。通过一系列条件优化,获得U（Ⅳ）和U（Ⅵ）的RSD分别为2.2%和1.9%,检出限为1.37μg/g。对实际样品进行测定,样品回收率均在65.5%～97.0%。

In this study,a method which could determine the valence states of trace uranium using inductively coupled plasma mass spectrometry（ ICP-MS） was established.1,10-phenanthroline monohydrate and hydroxylamine sulfate were used to mask Fe（ II） to protect U（ Ⅵ） from being reduced and prevent U（ Ⅳ） being oxidated,respectively.Hydrofluoric acid could dissolve silicate and form UF4 precipitation with U（ Ⅳ） in the presence of mixed carrier of coprecipitation.Supernatant fluid and precipitate were separated through centrifugation,dissolved by HNO_3-HClO_4 system and determined by ICP-MS.Through a series of optimization of conditions,RSD was obtained to be 2.15% and 1.87% respectively and detection limit was obtained to be 1.37 μg/g.Sedimentary samples were determined and the recoveries were all in 65.5% ～ 97.0%.