阴离子树脂Bio-Rad AG1-X8对黑色页岩中的Mo有很好的分离纯化效果.该方法可以有效去除Mo同位素分析过程中可能存在的同质异位素干扰(如Zr、Sr等),对其他金属元素的去除效果也比较理想.大部分基体元素如Fe、Ca、Na、Mn、Mg、Sr、A1、Cu、K等可以使用1 mol/L HF +0.5 mol/L HC1洗脱,随后使用4 mol/L HCl洗脱Ti和Zr,最后使用3mol/L HNO3洗脱Mo.在用单元素标准溶液过柱的过程中发现,样品中的Mo主要在前5mL 3 mol/LHNO3的淋洗液中洗脱,先淋洗出的溶液富集Mo的重同位素,后淋洗出的溶液富集Mo的轻同位素.当上柱的样品量较大时(Mo≥50μg),“柱基体效应”可以忽略不计,该化学纯化法适用于样品-标样交叉法和双稀释剂法；当样品量较小时(Mo＜ 50 μg),该化学分离方法只适用于双稀释剂法.%The anion exchange resin BioRad AG1-X8 can be used to separate Mo from matrix elements in black shale and other geological samples. Most matrix elements, such as Fe, Ca, Na, Mn, Mg, Sr, Al, Cu and K, were eluted firstly by 1 mol/L HF+ 0.5 mol/L HC1; then Ti and Zr were eluted by 4 mol/L HC1; and Mo was eluted lastly by 3 mol/L HNQ5. Sr, which leads Mo isotope fractionation when Mo isotopic composition is analyzed by MC-ICP-MS, can be separated completely from Mo. During the eluting, most Mo was eluted within the first 5 Ml HNQ3; the heavier Mo isotopes were collected first, then the lighter ones, so the eluant must be collected completely to avoid Mo isotope fractionation. When the amount of Mo in sample is large enough (≥50 μg), "column matrix effects" can be neglected and the Mo isotopic composition is unchanged after ion exchange separation, so the separation method is suitable for both sample-standard bracketing and double spiking techniques to calibrate the instrumental mass bias; nevertheless, due to "column matrix effects", this rnethod is suitable for double spiking only when the amount of Mo is small (<50μg).
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