Preconcentration of Ultra-Trace Elements in Various Samples

1. 建立了用ICP-ESA法测定钼和硅化钼中U和Th的方法。测定方法为：将样品0.1 g加热分解于HCI- hf中，得到的残留物溶于6M HCI中。然后加入NaOH将样品溶液的pH调节到约1，通过摇动混合物将Th提取到TTA-C_6H_6中。通过加入NaOH将水溶液的pH调整到约4。加入ta -C_6H_6后，摇匀提取U。在得到的有机相中，加入之前含有Th的C_6H_6溶液，将U和Th反萃取到3M HCI中。用C_6H_<12>洗涤水相后，将溶液应用于ICP-ES。根据建议的程序，可以确定U和Th的ppm水平。然而，为了进一步提高灵敏度，即ppt水平，应采用ICP-MS，目前研究正在进行中。微量元素富集及ICP-ES测定。建立了双硫腙- tpo萃取富集和ICP-ES测定微量元素的方法。所提出的方法使我们能够同时测定Co， Ni, Cu, Zn, Cd， Pb亚ppb水平，这些元素在Watarase河的水样中显示为：Cu: 85 <正负bbb50 5 ppb， Zu: 88 <正负> 0.1 ppb, Cd: 0.75 <正负> 0.002 ppb, Pb: 3.2 <正负>

1. Determination of alpha-emitters in semiconductor with ICP-ESA method for the determination U and Th in molybdenum and molybdenum silicide was developed by using ICP-ES. The procedure for the determination is as follows : 0.1 gram of a sample was decomposed in HCI-HF by heating, and the resulting residue was dissolved in 6M HCI. The pH of the sample solution was then adjusted to ca. 1 by adding NaOH, and Th was extracted into TTA-C_6H_6 by shaking the mixture. The pH of the aqueous solution was adjusted to ca. 4 by adding NaOH. After the addition of TTA-C_6H_6, the mixture was shaken to extract U. To the resulting organicphase, the previous C_6H_6 solution containing Th was added, U and Th were then back-extracted into 3M HCI. After washing the aqueous phase with C_6H_<12>, the solution was applied to ICP-ES.According to the proposed procedure, the ppm level of U and Th could be determined. However, for further sensitivity, namely ppt level, ICP-MS should be employed, and the research is now in progress.2. Preconcentration of trace elements and their determination with ICP-ES.A method for the preconcentration of trace elements by dithizone and TBPO-extraction and their determination with ICP-ES was also established. The proposed method enables us to determine sub-ppb level of Co, Ni, Cu, Zn, Cd, Pb simultaneously and these elements in a water sample taken from the Watarase River was shown to be : Cu : 85 <plus-minus> 5 ppb, Zu : 88 <plus-minus> 0.1 ppb, Cd : 0.75 <plus-minus> 0.002 ppb, Pb : 3.2 <plus-minus>