In the field of isotopic analysis, the absolute ratio of isotopes is of great significance. The absolute ratio of isotopes determines the atomic weight of elements and is also the fundamental parameter of isotopic analytical chemistry. For example, in the process of mass spectrometry element and isotope measurement, all kinds of interference correction need to use high-precision isotope absolute ratio to ensure the accuracy of the results. However, the accuracy of many existing absolute isotope ratio data is poor. Especially for elements with less than 4 isotopes such as vanadium and indium, which are interfered by other elements of the same weight at the same time, due to the inability to use the existing absolute ratio test methods such as double diluent method and external correction method, there is still a lack of high-precision absolute ratio data of isotopes. Li Weiqiang, Professor of the State Key Laboratory of metallogenic mechanism of endogenetic metallic deposits, Nanjing University, creatively combined the external correction method and the double diluent method to develop the "same heavy element diluent method" to test the absolute ratio of isotopes. In this method, the standard solution of adjacent elements with the same heavy element as the test element is used as diluent, and the mixed solution of diluent and test element is tested by mc-icp-ms. With the help of the characteristics of inductively coupled plasma (ICP), the isotopes of the two elements are ionized and received at the same time. In this way, we can use a correction method similar to the double diluent method, and use the isotope ratio of diluent elements to get the high-precision absolute isotope ratio of another element. The research team improved the calibration method of instrument fractionation of diluent of the same weight element to make the calibration of instrument fractionation coefficient between elements possible.
Professor Li Weiqiang's team applied the "isoheavy element diluent method" to a variety of element pairs, and accurately measured the isotopic absolute ratios of 46ca / 44Ca, 48Ca / 44Ca, 50V / 51V, 50Cr / 52Cr, 64ni / 62ni and 113in / 115In. The absolute ratio obtained by the measurement is consistent with the reference value in the literature, and the accuracy is up to or better than the order of one thousandth. Among them, the absolute ratio of 50V / 51V and 113in / 115In obtained in this study has the highest accuracy in the published data. This shows that this method can accurately measure the absolute isotope ratio and effectively correct the instrumental fractionation coefficient of different elements, especially for the absolute isotope ratio measurement of elements with less than 4 isotopes.
Compared with the absolute ratio test methods such as double diluent method and external correction method, the "same heavy element diluent method" can not only test the elements with less than 4 isotopes or other elements interfered by the same heavy element, but also does not need expensive synthetic isotope diluent and complex diluent correction. This method can also increase the mass number signal of low abundance isotopes (such as 46ca, 48Ca and 50V) by adding the same heavy element, so as to effectively measure the isotope ratio accuracy of these low abundance isotopes. In addition, this study improves the law of isotopic instrument fractionation, and provides an effective method to calibrate the isotopic instrument fractionation of different elements. The above achievements were recently published in analytical chemistry, the first-class academic journal of International Analytical Chemistry, under the title of "isobaric spike method for absolute Islamic ratio determination by MC-ICP-MS". SHUAIKANG, Ph.D. student of our college, is the first author of the paper, Professor Li Weiqiang is the author of the paper, and the author of the paper also includes Professor Hui Hejiu. Qin Liping, Professor of University of science and technology of China, and Zhang Zhaofeng, researcher of Guangzhou Institute of geochemistry provided assistance for tims measurement of Cr and Ca isotope standard samples, respectively. This research is supported by the pilot B project of Chinese Academy of Sciences (xdb41000000) and the National Space Administration Project of China (d020205). Paper link: https://pubs.acs.org/doi/full/10.1021/acs.anlchem.9b04160 source: National Key Laboratory of metallogenic mechanism of endogenetic metal deposits, Nanjing University, the copyright of this paper belongs to the original author, the purpose of this paper is to share excellent scientific research results, the original author was not contacted in time when the article was pushed, if the source is marked incorrectly or infringes your rights and interests, please let me know We will delete it immediately. For more details and references, please refer to the original text and click at the bottom of the article (read the original). Welcome to submit & submit details click to view
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