Method for determining boron isotopic composition with static double-receiving method by positive thermal ionization mass spectrometry

Abstract

The invention relates to a method for determining boron isotopic composition with static double-receiving method by a positive thermal ionization mass spectrometry, wherein the 309 and 308 ion peaks are statically received simultaneously by two Faraday cups by adjusting the two parameters of FocusQard and DispersionQuad in a focusing optical system, and the determination of high-accuracy boron isotopic composition is finished. The method comprises the following steps: (1) determining the FocusQard and DispersionQuad parameters in ion source optical focusing; (2) determining the two parallel cups and cup parameters of a Faraday receiver; (3) and determining the receiving mass number of the central cup of the Faraday receiver. The method establishes a method for determining boron isotopic composition using double-Faraday-cup static receiving method without changing high-pressure parameter and Faraday cup hardware setting; compared with dynamic peak skip-scanning method, the data acquisition time is greatly shortened, and the sensitivity and inner and outer accuracies of the determination of boron isotopic composition using positive thermal ionization method are improved.

Description

technical field [0001] The invention belongs to the technical field of mass spectrometry, and relates to a method for determining the composition of boron isotopes, in particular to a method for simultaneously receiving high mass-to-charge ratio Cs using two Faraday cups 2 BO 2 + Ions (ie, m / e=308 and 309) are a method for determining the boron isotope composition with high precision. Background technique [0002] Natural boron isotopes (δ 11 B) The variation range is large, and the B isotopic composition varies significantly in different environments and different geological processes. Therefore, the boron isotopic composition has been widely used in the fields of crust and mantle evolution, ore deposit geology, hydrochemistry and environmental geochemistry, marine environment and paleoenvironment. With the improvement of measurement methods and the improvement of test accuracy, boron isotope, as a sensitive and reliable indicator, has made outstanding achievements in th...

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Problems solved by technology

[0018] The object of the present invention is to provide a method for measuring boron isotope composition by the static double-receiving method of a positive thermal ionization mass spectrometer to solve the problem of positive thermal ionization mass spectrometry PTIMS-Cs 2 BO 2 + Cs with a large mass-to-charge ratio in the determination of boron isotopic composition by static double-acceptance method 2 BO 2 + (m / e=309 and 308) ions receive the technical problem completely at the same time, overcome the limitations or defects such as the high pressure of the instrument ion source accelerator that cannot be adjusted and artificially fixed two parallel Faraday cups, poor flexibility and signal instability, combined with the mass spectrometer ion source optics The principle of lens focusing, by adjusting the focusing optical system (Zoom Optics), two Faraday cups can receive 309 and 308 ions at the same time, and establish a method for high-precision determination of boron isotope composition by static reception method

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