第三液相富集-石墨炉原子吸收光谱法测定高温合金中痕量碲

Determination of trace tellurium in superalloy by graphite furnace atomic absorption spectrometry after enrichment with the third liquid phase

高温合金成分复杂，基体元素和合金元素严重干扰石墨炉原子吸收光谱法（GF-AAS）测定痕量碲。因而需要采用萃取技术分离干扰元素。二安替比林甲烷（DAM）·氢碘酸（HI）三相体系萃取碲具有较高的选择性。该体系中形成的第三液相为二安替比林甲烷（DAM）·氢碘酸（HI）缔合物在三氯甲烷和苯混合溶剂中的分散相。实验优化了二安替比林甲烷（DAM）·氢碘酸（HI）三相体系萃取条件，结果显示碲在第三液相、第二相和水相中分配比为8400：1600：1。该萃取体系第三液相中碲的富集倍数高达21倍，同时可有效分离高温合金中基体元素和合金元素，消除了这些元素对石墨炉原子吸收光谱法测定碲的干扰。将第三液相稀释后直接进样，选用硝酸钯为改进剂，优化石墨炉升温程序，解决了有机物引起的背景干扰问题，获得了稳定的碲吸光度，进而建立了“二安替比林甲烷·氢碘酸第三液相富集一石墨炉原子吸收光谱法测定高温合金中痕量碲”的新方法。方法检出限为0．055μg／g。用实验方法分析高温合金标准物质中0．5O～83μg／g的痕量碲，测定值与认定值一致，相对标准偏差（RSD，n=8）不超过2O％。

The composition of superalloy is complicated,so the determination of trace tellurium by graphite furnace atomic absorption spectrometry(GF-AAS)is seriously affected by matrix and alloying elements.The interference elements should be separated firstly by extraction.The diantipyrylmethane(DAM)-hydroiodic acid(HI)three-phase system has high selectivity to the extraction of tellurium.The third liquid phase formed in this system is the dispersion phase of DAM-HI associated complex in mixed solvent of trichloromethane and benzene.The extraction conditions of DAM-HI three-phase system were optimized in this study.The results showed that the distribution ratio of tellurium in the third liquid phase,the second phase and water phase was 8 400∶1 600∶1.The enrichment factor of tellurium in the third liquid phase of this extraction system was up to 21.Meanwhile,the matrix and alloying elements in superalloy could be effectively separated,eliminating the interference of these elements with the determination of tellurium by graphite furnace atomic absorption spectrometry.The third liquid phase was directly injected after dilution.The palladium nitrate was used as modifier.Moreover,the temperature procedure of graphite furnace was optimized.The background interference problem caused by organic matters was solved,and the stable absorbance of tellurium could be obtained.Consequently,a new determination method of trace tellurium in high temperature alloy by graphite furnace atomic absorption spectrometry(GF-AAS)after enrichment with the third liquid phase(DAM-HI)was established.The detection limit of method was 0.055μg/g.The proposed method was applied to the determination of trace tellurium(0.50-83μg/g)in certified reference material of superalloy.The found results were consistent with the certified values.The relative standard deviation(RSD,n=8)was less than 20%.