STUDIES ON BEHAVIOR OF HIGH-TECHNOLOGY RELATED ELEMENT GALLIUM IN SIOL ENVIRONMENT

为了建立土壤样品中痕量镓的分析方法，采用涂钽石墨管，用石墨炉原子吸收法（GFAAS）测定土壤样品中痕量镓。土壤中的基质元素如Al、Ca、Fe、K、Mg、Na在100 - 1，000 ppm浓度范围内均显示出Ga的信号增强。本实验中使用Al（500 ppm）、Ni（500 ppm）和IM硝酸的混合物作为最合适的基体改进剂。采用基体改进剂涂钽石墨炉原子吸收光谱法测定了日本地质调查所岩石标准物质JA-1、JB-3、JLk-1中的镓。采用标准加入法测定，结果与推荐值符合较好。用上述方法测定的土壤中镓含量范围为20 ~ 50 ppm，与日本土壤中的报道值一致。用电感耦合等离子体质谱法（ICP-MS）测定了土壤中镓的含量。对于水样的分析，在ppt浓度范围内得到线性校准曲线。但在测定Ga时，C10分子离子存在严重的质量重叠干扰。用5-辛氧基甲基-8-羟基喹啉在氯仿中从土壤基质中萃取镓，然后用硝酸反萃取。为了补偿提取效率，建议使用同位素稀释质谱法，以获得准确的结果在土壤样品中镓。

In order to establish an analytical method for trance determination of gallium in soil samples, graphite furnace atomic absorption spectrometry (GFAAS) using a Ta-coated graphite tube was examined. Matrix elements in soil such as Al, Ca, Fe, K,Mg, Na each showed signal enhancement of Ga in the concentration range from 100 to 1,000 ppm. A mixture of Al (500ppm), Ni (500ppm) and IM nitric acid was used as a most suitable matrix-modifier in this experiment. Gallium in rock reference materials (JA-1, JB-3, JLk-1) issued by Geological Survey of Japan was determined by Ta-coated GFAAS using the matrix-modifier. The analytical values obtained were in good agreement with the recommended values when standard additions method was employed. Gallium contents in soils determined by the above-mentioned method ranged from 20 to 50 ppm, consistent with reported values on Japanese soils.Inductively coupled plasma mass spectrometry (ICP-MS) was applied for the determination of Ga in soil digests. For the analysis of water samples, a linear calibration curve was obtained in the concentration range of ppt. However, there exists a severe mass overlapping interference due to C10 molecular ion in the case of Ga determination. An extraction of Ga from the soil matrix with 5-octyloxymethyl-8-quinolinol in chloroform followed by back-extraction with nitric acid was performed. In order to compensate for extraction efficiency, the use of isotope dilution mass spectrometry was recommended to obtain an accurate result on Ga in soil samples.