A simple, rapid and effective solvent extraction separation of rare earth elements (REEs) has been developed for their determination in geological samples such as rock, soil and core samples by inductively coupled plasma optical emission spectrometry (ICP-OES). Rare earth elements form neutral complexes with the bi-dentate ligand, 2,3-dihydroxynaphthalene (2,3-H₂ND), and are extracted into ethyl acetate at an alkaline pH of 9–10. All these elements are then quantitatively stripped off into the aqueous phase using dilute hydrochloric acid and then determined by ICP-OES. Different variables such as pH of the solution, reagent concentration, solvent, stripping solution, diverse ions, etc. affecting the simultaneous quantitative extraction of lanthanides followed by their determination using ICP-OES have been studied in detail. The method has been validated by analyzing a set of certified reference materials of rock and soil samples such as SY-2, SY-3, GSP-2 and SO-2. The results obtained by the proposed method for a set of silicate rock and core samples are compared to those obtained by other standard separation techniques such as oxalate co-precipitation using calcium as a carrier. The precision (as % RSD) of the proposed method varied over a range of 1 to 10% depending on the concentration of the lanthanides. The developed method involving simultaneous separation and determination of individual lanthanides by ICP-OES is an improvement on the existing method, where only total lanthanides were determined colorimetrically using arsenazo-III, and does not require any counter cation. The proposed method is comparatively more environment friendly.

中文翻译：

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地质样品中稀土元素的萃取分离及其电感耦合等离子体发射光谱法测定

已经开发了一种简单，快速且有效的溶剂萃取分离稀土元素（REE）的方法，用于通过电感耦合等离子体发射光谱（ICP-OES）测定地质样品（例如岩石，土壤和岩心样品）中的稀土元素。稀土元素与双齿配体2,3,2-二羟基萘（2,3-H ₂ ND）形成中性络合物，并在9-10的碱性pH下萃取到乙酸乙酯中。然后使用稀盐酸将所有这些元素定量分离为水相，然后通过ICP-OES测定。不同的变量，例如溶液的pH，试剂浓度，溶剂，汽提溶液，各种离子等。已经详细研究了影响镧系元素同时定量萃取并随后使用ICP-OES测定镧系元素的方法。该方法已通过分析一组经认证的岩石和土壤样品参考材料（例如SY-2，SY-3，GSP-2和SO-2）进行了验证。通过提议的方法获得的一组硅酸盐岩石和岩心样品的结果与通过其他标准分离技术（例如以钙为载体的草酸盐共沉淀）获得的结果进行了比较。根据镧系元素的浓度，所提出方法的精密度（以RSD％计）在1％至10％的范围内变化。ICP-OES同时分离和测定单个镧系元素的已开发方法是对现有方法的改进，使用砷偶氮-III比色法只测定了镧系元素的总量，不需要任何抗衡阳离子。所提出的方法相对更环境友好。