| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1994: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1993: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
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.
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