Development and evaluation of substoichiometric isotope dilution mass spectrometry as definitive method

将同位素稀释质谱仪(IDMS)与亚化学计量学相结合，提出了一种新的分析方法--亚化学计量比同位素稀释质谱仪(SIDMS)。采用溶剂萃取法和离子交换法分离痕量铁(III)和铜(II)，并用微波诱导等离子体质谱(MIP-MS)和电感耦合等离子体质谱(ICP-MS)进行了同位素测定。将这些方法应用于一些环境标准物质，评价了它们的准确度、精密度和实用性。1)利用基于氢键的协同效应考察了铁(III)的亚化学计量萃取。在过量3，5-二氯苯酚存在下，用亚化学计量比的4-异丙基托波酮萃取0.1杯水平的Jron(III)。2)研究了MIP-MS测定有机溶液中铁的最佳条件。铁的SIDMS用于海藻标准物质(NIES 9号)，证实了铁的测定值与证明值很好地吻合。3)研究了亚化学计量离子交换分离测定痕量铁。通过阳离子交换将环己烷-1，2-四乙酸二胺形成的阴离子铁(III)络合物与未反应的铁(III)分离。4)用二乙基二硫代氨基甲酸锌在四氯化碳中亚化学计量萃取铜(II)，然后用亚化学计量的钯(II)反萃取铜(II)。5)铜的SIDMS被应用于海洋沉积物标准物质(NIES NO.12)。测定的含量接近NIES报告的参考值。

A new analytical method, substoichiometric isotope dilution mass spectrometry (SIDMS), was proposed by combining isotope dilution mass spectrometry (IDMS) with substoichiometry. Solvent extraction and ion exchange were studied for the substoichiometric separation of trace iron(III) and copper(II), and a microwave induced plasma mass spectrometer (MIP-MS) and ICP-MS were used for the isotope measurement. By applying these methods to some environmental reference materials, the following were evaluated : accuracy, precision and practicability.1) The substoichiometric extraction of iron(III) was examined using synergistic effect based on hydrogen bond. Jron(III) in 0.1 mug levels was extracted with a substoichiometric amount of 4-isopropyltropolone in the presence of an excess of 3,5- dichlorophenol as a synergist.2) Optimum conditions in the MIP-MS measurement were examined for iron in organic solutions. The SIDMS for iron was applied to a seaweed reference material (NIES No.9), and it was confirmed that the determined value of iron well agreed with the certified value.3) The substoichiometric ion exchange separation was examined for trace iron(III). The anionic iron(III) complex formed with a substoichiometric amount of cyclohexane-1,2-diaminetetraacetate was separated from unreacting iron(III) by the cation exchange. The determination of iron in l0ng levels by SIDMS can be expected.4) Copper(II) was substoichiometrically extracted with zinc(II) diethyldithiocarbamate in carbon tetrachloride, and then the extracted copper(II) was back-extracted with a substoichiometric amount of palladium (II) into the aqueous phase. The determination of copper in 10ng levels can be expected.5) The SIDMS for copper was applied to a marine sediment reference material (NIES No.12). The content determined was close to the reference value reported by NIES.