Nemoto Shigeki, Nomura Masao, Oi Takao
Faculty of Science and Technology, Sophia University, Tokyo, Japan.
Isotopes Environ Health Stud. 2013 Jun;49(2):257-68. doi: 10.1080/10256016.2013.770393.
Breakthrough mode liquid chromatography was employed to investigate calcium (Ca) isotope fractionation in methanol medium. Highly porous silica beads, the inner pores of which were embedded with a benzo-18-crown-6 ether resin, were used as column packing material. Enrichment of heavier isotopes of Ca was observed in the frontal part of the respective Ca chromatograms. The values of the isotope fractionation coefficient (ϵ) were in the order of 10(-3) at 25 °C. Use of methanol as solvent has little advantage over the aqueous system as far as the values of ϵ are concerned. However, a substantial improvement was observed concerning the adsorption capacity of the crown ether resin for Ca ions. Molecular orbital calculations supported the present isotopic results in a qualitative fashion.
采用突破模式液相色谱法研究甲醇介质中钙（Ca）同位素分馏。使用高度多孔的硅胶珠作为柱填充材料，其内部孔隙中嵌入了苯并 - 18 - 冠 - 6醚树脂。在各个Ca色谱图的前部观察到较重Ca同位素的富集。在25℃下，同位素分馏系数（ϵ）的值约为10^(-3)。就ϵ值而言，使用甲醇作为溶剂相对于水体系几乎没有优势。然而，在冠醚树脂对Ca离子的吸附容量方面观察到了显著改善。分子轨道计算以定性方式支持了目前的同位素结果。
