https://scholars.lib.ntu.edu.tw/handle/123456789/38138
標題: | Measurement of Attogram Quantities of 231Pa in Dissolved and Particulate Fractions of Seawater by Isotope Dilution Thermal Ionization Mass Spectroscopy | 作者: | Shen, Chuan-Chou Cheng, Hai Lawrence Edwards, R. Bradley Moran, S. Edmonds, Henrietta N. Hoff, John A. Thomas, Rebecca B. |
關鍵字: | Filtration; Igneous rocks; Ionization; Isotopes; Mass spectrometry; Protactinium; Suspensions (fluids); Thermal ionization mass spectrometry (TIMS); Seawater; isotope; protactinium; sea water; article; dilution; mass spectrometry; particulate matter; statistical analysis; water sampling | 公開日期: | 2003 | 卷: | 75 | 期: | 5 | 起(迄)頁: | 1075-1079 | 來源出版物: | Analytical Chemistry | 摘要: | A technique has been developed to quantify ultratrace 231Pa (50-2000 ag; 1 ag = 10-18 g) concentrations in seawater using isotope-dilution thermal ionization mass spectrometry (TIMS). The method is a modification of a process developed by Pickett et al. (Pickett, D. A.; Murrell, M. T.; Williams, R. W. Anal. Chem. 1994, 66, 1044-1049) and extends the technique to very low levels of protactinium. The procedural blank is 16 ± 15 ag (2σ), and the ionization efficiency (ions generated/atom loaded) approaches 0.5%. Measurement time is <1 h. The amount of 231Pa needed to produce 231Pa data with an uncertainty of ±4-12% is 100-1000 ag (∼3 × 105 to 3 × 106 atoms). Replicate measurements made on known standards and seawater samples demonstrate that the analytical precision approximates that expected from counting statistics and that, based on detection limits of 38 and 49 ag, protactinium can be detected in a minimum sample size of surface seawater of ∼2 L for suspended particulate matter and <0.1 L for filtered (<0.4 μm) seawater, respectively. The concentration of 231Pa (tens of attograms per liter) can be determined with an uncertainty of ±5-10% (2σ) for suspended particulate matter filtered from 5 to 10 L of seawater. For the dissolved fraction, 0.5-1 L of seawater yields 231Pa measurements with a precision of 1-10%. Sample size requirements are orders of magnitude less than traditional decay-counting techniques and significantly less than previously reported ICP-MS techniques. Our technique can also be applied to other environmental samples, including cave waters, rivers, and igneous rocks. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/172683 http://ntur.lib.ntu.edu.tw/bitstream/246246/172683/1/05.pdf |
DOI: | 10.1021/ac026248r |
顯示於: | 地質科學系 |
在 IR 系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。