1995 Fiscal Year Final Research Report Summary
Studies on the development of specific microbes for pre-concentration and analysis of heavy metals from environmental samples
| Project/Area Number |
06640787
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
分離・精製・検出法
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| Research Institution | OKAYAMA UNIVERSITY |
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Principal Investigator |
IKATSU Hisayoshi OKAYAMA Univ., Administration Center for Enviromental Science and Technology, Staff assistant, 環境管理センター, 助手 (10260663)
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| Project Period (FY) |
1994 – 1995
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| Keywords | specific microbes / analysis of selenium / bioaccumlation / atomic absorption spectrometry / pre-concentration of heavy metals |
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| Research Abstract |
The determination method of selenium in water samples by graphite furnace atomic absorption spectrometry (GF-AAS) after pre-concentration with lyophilized bacteria was developed. Eight strains of bacteria and one yeast were tested for their ability to bioaccumulate selenium. High selenium-absorbing ability was found in Bacillus cereus which was separated from specific microbes for wastewater treatment systems.
One milliliter of HNO_3 (6%) and 10 mg of lyophilized bacteria were added to 50 ml of sample solution, and the solution stirred for 2 hours. The suspended bacteria was then centrifuged, and the precipitate was dissolved with 0.7 ml of HNO_3 (30%) and 0.3 ml of plladium solution (1000mg/l). The dissolved solution was injected into the graphite tube and selenium peak height was measured under the optical GF-AAS operating conditions. The ramp ashing method was used to sample solutions contatining selenium and bacterial cells. The sensitivity of selenium determination was most raised
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under the final ash temperature of 1500 ﾟC.No interfering effects were found for coexisting 100 ug/l of various metallic ions on the 10 ug/l of selenium analysis. On the other hand, the depressant effects were caused by 1000 ug/l of matallic anions. By the proposed method, 0.5-30 ug/l of selenium could be quantitatively recovered and determined with the relative standard deviation of 2.2 %. This method was applied to the determination of selenium in wastewaters and the results were in good agreement with them by the Cu-DDTC coprecipitation/GF-AAS method. Pre-concentration of selenium from gas washer wastes was not possible with this method due to the high salinity of the solutions.
Some of the advantages of using specific microbes as a pre-concentrator include the use of cheap and renewable biomass, concentration of specific metals, greatly reduced volume of waste produced, a low blank and the small particle diameter. It is important to study the metal-accumulating characteristics of many bacterial specis to identify possible individual differences and exploit them. Further researches involving the selection of specific bacteria having high ability of selenium concentration and the application of specific microbes are currently under investigation. Less
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