超高分解能FT-ICRMSを用いたバイカル湖水中未同定溶存有機物の解明

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Lake Baikal, located on the north-eastern borders of Central Asia, is the deepest (maximum depth 1,700 m) and one of the largest lakes in the world. To elucidate the chemical composition of dissolved organic matter (DOM) in the Lake Baikal, we applied high resolution fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to the lake water samples. Water samples were taken at the deepest point of Lake Baikal and its inflowing Barguzin River mouth on August 2005. The sample water was filtrated on board and DOM was extracted using C 18 solid-phase extraction disks (Kim et al., 2003^a). The extracted samples on the disks were analyzed by a 9.4-T FT-ICR mass spectrometer at the National High Magnetic Field Laboratory (Tallahassee, FL, USA) in negative ionization mode with a needle voltage of -2.0 kV. From the FT-ICR mass analysis, 3511, 2862 and 2191 peaks were detected (S/N>3) in river and 5 m- and 945 m- depth lake water samples, and more than 80% of the peaks were assigned within ± 1.0 ppm error. Using van Krevelen Diagrams (van Krevelen, 1950), we found that the main component of L. Baikal DOM was allochthonous lignin-like organic molecule, and that autochthonous lipid- and protein-like molecules were also found in surface water.
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