Validation of methylmercury determinations in aquatic systems by alkyl derivatization methods for GC analysis using ICP-IDMS
Validation of methylmercury determinations in aquatic systems by alkyl derivatization methods for GC analysis using ICP-IDMS
复制标题
DOI：
10.1021/ac010366
复制
发表时间：
2001-08-15
影响因子：
7.4
通讯作者：
Heumann, KG
中科院分区：
文献类型：
--
作者：
Demuth, N;Heumann, KG
利用电感耦合等离子体四极杆质谱仪(ICPMS)和特定物种的甲基汞峰，采用同位素稀释质谱仪(IDMS)验证了常用的气相色谱测定甲基汞(MeHg+)的方法，该方法基于NaBEt4衍生化生成挥发性甲基乙基汞。用富汞氯化汞与甲钴胺反应合成了(MeHg2+)-Hg201。通过对不同环境水样的分析发现，在大多数情况下，甲基汞+转化为元素汞(Hg0-)。通过对合成溶液的研究，可以得出结论：卤化物离子是导致这一转化过程的原因。氯化物和溴化物使MeHg+转化为Hg0-，而碘化物使其转化为Hg2+和Hg0-。研究还表明，甲基汞的转化只发生在衍生化过程中。与乙基化相比，NaBPr4的丙基化不会引起任何转化，但在GC/ICPIDMS的应用中，丙基化和乙基化都能获得准确的甲基汞测定结果。这项工作证明了同位素标记的元素化合物在验证元素形态形成方法和特定物种的IDMS分析方面的强大威力。
Isotope dilution mass spectrometry (IDMS), using an inductively coupled plasma quadrupole mass spectrometer (ICPMS) and a species-specific methylmercury spike was applied to validate the commonly used GC method for methylmercury (MeHg+) determination, which is based on the formation of volatile methylethylmercury by derivatization with NaBEt4. The spike compound, (MeHg+)-Hg-201, was synthesized by reaction of Hg-201-enriched mercury chloride with methylcobalamin. By analyzing different environmental aquatic samples, it was found that in most cases, transformation of MeHg+ into elemental mercury (Hg-0) took place. From investigations of synthetic solutions, it could be followed that halide ions are responsible for this transformation process. Chloride and bromide converted MeHg+ into Hg-0, whereas iodide caused transformation into Hg2+ and Hg-0. It could also be shown that transformation of MeHg+ took place only during the derivatization step. In contrast to ethylation, propylation by NaBPr4 did not cause any transformation; however, accurate results of MeHg+ determinations could be obtained by propylation as well as by ethylation when GC/ICP-IDMS was applied. This work demonstrates the great power of isotopically labeled element compounds for the validation of element speciation methods and for species-specific IDMS analyses.