用ETV-ICP-MS研究Cr、Ni、Zr、Nb、Yb在石墨炉中的蒸发/原子化机理

Investigation of the Vaporization and Atomization Mechanisms of Cr,Ni,Zr,Nb,and Yb in Graphite Furnace by ETV-ICP-MS

本文以电热蒸发电感耦合等离子体质谱(ETV-ICP-MS)为手段,探讨了Cr、Ni、Zr、Nb和Yb在石墨炉中的蒸发/原子化机理;比较了不同化学改进剂存在条件下,Cr、Ni、Zr、Nb和Yb的蒸发行为和在石墨炉原子吸收(GFAAS)中的原子化行为;考察了石墨炉温度和ICP功率等实验参数对上述元素发射强度及轮廓的影响。结果表明,Pd和Mg化合物的存在对Cr、Ni、Zr、Nb和Yb的蒸发/原子化行为没有明显的化学改进作用;然而,以聚四氟乙烯(PTFE)为化学改进剂时,可显著改善Cr、Ni、Zr、Nb和Yb的蒸发行为,避免难熔碳化物的形成,降低待测物的蒸发温度;对Cr和Ni的GFAAS信号强度略有增强;但是,由于Yb、Nb和Zr氟化物的离解键能很高,难以离解/原子化,PTFE的存在反而降低了Yb、Nb和Zr在GFAAS中的信号强度。

The mechanisms of vaporization/atomization of Cr,Ni, Zr,Nb and Yb in graphite furnace have been studied using electrothermal vaporization inductively coupled plasma mass spectrometry （ETV-ICP-MS）. The behaviors of vaporization/atomization of Cr,Ni,Zr,Nb and Yb in a graphite furnace with and without chemical modifiers （Pd,Mg,PTFE） were compared. The effects of graphite furnace temperature and ICP power on the signal intensities and the signal profiles of Cr,Ni,Zr,Nb and Yb in ETV-ICP-MS were investigated. It was found that： （1） Pd and Mg compounds have no obvious modification on the behaviors of vaporization and atomization of Cr, Ni,Zr,Nb and Yb in the graphite furnaces （2） In the presence of PTFE,the behaviors of vaporization of Cr,Ni,Zr,Nb and Yb were remarkably changed,the formation of refractory carbides were successfully circumvented, and the vaporization temperatures were decreased significantly;（3） The signal intensities of Cr and Ni in GFAAS were enhanced in some extent. However,those of Yb, Nb and Zr were restrained greatly. It was attributed to the high bond dissociation energies of the fluorides of Yb,Nb and Zr,which caused ineffective dissociation/atomization of analytes in the graphite furnace.