Chelex-100 ion-exchange filter membranes for preconcentration in x-ray fluorescence spectrometric analysis of water
Chelex-100 ion-exchange filter membranes for preconcentration in x-ray fluorescence spectrometric analysis of water
复制标题
Chelex-100 离子交换滤膜，用于水的 X 射线荧光光谱分析中的预浓缩
DOI：
10.1021/ac50017a011
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发表时间：
1977
影响因子：
7.4
通讯作者：
B. Vanderborght
中科院分区：
文献类型：
--
作者：
R. Grieken;C. M. Bresseleers;B. Vanderborght
通过一对Chelex-100离子交换膜过滤200 mL水样，在2-3 bar压力下，pH 7至8，不少于20 min，导致许多痕量金属的有效收集，其形式是随后X射线荧光分析的理想选择。由于获得了约1250的富集因子，因此检测限为1-ppb水平。精密度估计在10-15%范围内。浓度与测得的X-射线产额之间呈良好的线性关系，其总膜对容量为0.07毫欧。Chelex-100膜对通常丰富的碱金属和碱土金属离子的显着亲和力，以及它们有限的容量，限制了所述技术对具有非常低的碱金属和碱土金属含量的样品的适用性。然而，它很少适用于水溶液样品。直接照射带有薄聚酯薄膜底部的测量瓶中的含水样品，导致过渡金属的典型灵敏度为0.3-5 ppm（2）。当要求灵敏度在ppb范围内时，必须首先对痕量金属进行预富集，而困难显然在于制备含有所有元素的靶，这些元素充分富集并充分均匀分布，以便进行灵敏和可靠的分析。X射线荧光法已与沉淀和共沉淀法、蒸发法、溶剂萃取法、螯合法、活性炭吸附法、离子交换树脂法或固定化官能团的硅胶法结合使用。
Filtering a 200-mL water sample through a pair of Chelex-100 Ion-exchange membranes, under a 2-3 bar pressure, at pH 7 to 8 In not less than 20 min, leads to an efficient collection of many trace metals In a form that Is Ideal for subsequent x-ray fluorescence analysis. Since enrichment factors around 1250 are obtained, the detection limits are at the 1-ppb level. The precision Is estimated tobe In the 10-15% range. A perfectly linear relationship between concentration and measured x-ray yield Is obtained up to the total membrane pair capacity of 0.07 mequlv. The significant affinity of Chelex-100 membranes for the—usually abundant—alkali and alkaline earth Ions, together with their limited capacity, restricts the applicability of the described technique to samples with a very low alkali and alkaline earth content.X-ray fluorescence is essentially a multielement, simple, rapid, andcheap analytical technique. Yet it is rarely applied to aqueous samples. Direct irradiation of aqueous samples in a measuring vial with a thin Mylar bottom leads to typical sensitivities for transition metals in the order of 0.3-5 ppm (2). When sensitivities in the ppb region are required, the trace metals must first be preconcentrated and the difficulty lies obviously in preparing targets containing all elements sufficiently enriched and distributedwith sufficient uniformity to permit sensitive and reliable analysis. X-ray fluorescence has been employed in combination with precipitation and coprecipitation, evaporation, solvent ex-traction, chelation, and adsorption on activated carbon, use of ion-exchange resin or of silica gel with immobilized functional groups.