盐湖卤水中微量钒的浓度测定

为了测定盐湖卤水中微量钒的浓度，开发了一个钒的分离纯化流程来降低大量的共存离子的基质效应。该分离纯化流程包括萃取和反萃两个步骤。详细地研究了影响钒纯化效率的各种因素，得到钒的最佳分离纯化条件为:以正己烷为稀释剂，有机相中D2EHPA和TBP的体积百分比分别为30%及20%，在pH为3.0时萃取30 min；然后用3 mol/L H₂SO₄反萃 10 min。基于此分离纯化流程，将两个实际盐湖卤水样品中的微量钒纯化后，再用电感耦合等离子体质谱仪(ICP-MS)测定其浓度，该ICP-MS对51V 的检测灵敏度和检测限别为53 171 cps/(μg/L) 和1.88 ng/L。所得实际盐湖卤水钒测定结果的加标回收率接近100%而相对标准偏差低于0.6%，表明该方法可用于实际复杂体系中微量钒的浓度测定，例如海水和盐湖卤水。

Determining the Concentration of Trace Vanadium in Natural Saline Lake Brines

To determine the concentration of trace vanadium in saline lake brines, a vanadium pre-purification process is established to reduce the matrix effect of the huge coexisting ions. Two steps, extraction and stripping, are included in the process. The factors affecting the vanadium purification efficiencies are investigated in detail and the optimum conditions are determined to be: vanadium in the solutions was extracted by the organic phase containing 30% D2EHPA (v/v), 20% TBP (v/v) in n-hexane for 30 min at pH 3.0, and then stripped with 3 mol/L H₂SO₄ for 10 min. Trace vanadium in two natural brine samples are pre-purified using this process and their concentrations are determined by inductively coupled plasma-mass spectrometry (ICP-MS) with sensitivity and limit of detection (LOD) for 51V are 53 171 cps/(μg/L) and 1.88 ng/L, respectively. The standard addition recoveries of the brine samples are ~100% but with small relative standard deviations (RSD<0.6%), indicating that the method can be used to measure the concentration of trace vanadium in natural complicated waters, such as seawater and saline lake brines.