~(84)Sr稀释剂中锶同位素组成的准确测定
|
摘要
在化学分析技术中,同位素稀释法是公认的具有绝对测量性质的方法 ,其测量结果准确,不确定度小。在锶同位素组成测定中,同位素稀释法可同时得到样品中锶元素含量和同位素比值,但稀释剂的加入,使稀释剂和混合样品中锶同位素的质量分馏校正成为难点。采用数学迭代法,建立了~(84)Sr稀释剂同位素测量过程中的质量分馏因子的计算方法 ,利用指数近似模式校正方法建立了稀释分析中锶混合样品中锶同位素的质量分馏因子和样品中锶同位素比值的计算方法,提高了同位素稀释法分析样品锶同位素比值准确性。
In chemical analysis, isotopic dilution method is recognized as an absolute measurement method with accurate measurement results and small uncertainty. In the determination of strontium isotope composition, the isotopic dilution method can be used to determinate the strontium content and the isotopic ratios of the samples. However, the addition of strontium spike makes it difficult to calibrate strontium isotope mass fractionation in strontium spike and the mixture of samples+spike. In this study, the calculation method of mass fractionation factor for the measurement of isotopic ratios of spike has been established by mathematical iteration method. The mass fractionation factor of strontium isotopes in the mixture of samples+spike and the isotopic ratio of strontium in sample were calculated by using the exponential approximate correction method. As a result, the accuracy of sample strontium isotopic ratios has been improved.
In chemical analysis, isotopic dilution method is recognized as an absolute measurement method with accurate measurement results and small uncertainty. In the determination of strontium isotope composition, the isotopic dilution method can be used to determinate the strontium content and the isotopic ratios of the samples. However, the addition of strontium spike makes it difficult to calibrate strontium isotope mass fractionation in strontium spike and the mixture of samples+spike. In this study, the calculation method of mass fractionation factor for the measurement of isotopic ratios of spike has been established by mathematical iteration method. The mass fractionation factor of strontium isotopes in the mixture of samples+spike and the isotopic ratio of strontium in sample were calculated by using the exponential approximate correction method. As a result, the accuracy of sample strontium isotopic ratios has been improved.
引文
[1]DZ/T 0184.6-1997钐钕同位素地质年龄和钕同位素比值测定中华人民共和国地质矿产行业标准[S].北京:中华人民共和国地质矿产部,1997.
[2]DZ/T 0184.4-1997岩石、矿物铷锶同位素地质年龄及锶同位素比值的测定中华人民共和国地质矿产行业标准[S].北京:中华人民共和国地质矿产部,1997.
[3]Boelrijk N A I M.A general formula for double isotope dilution analysis[J].Chemical Geology,1968,3(4):323-325.
[4]Russell W A,Papanastassiou D A,Tombrello T A.Ca isotope fractionation on the Earth and other solar system materials[J].Geochimica et Cosmochimica Acta,1978,42:1 075-1 090.
[5]Gioia S M C L,Pimentel M M.The Sm-Nd Isotopic Method in the Geochronology Laboratory of the University of Brasília[J]An.Acad.Bras.Ci.,2000,72(2):219-245.
[6]Russ G P.Inter-Laboratory Uranium Double-Spike Experiment[J].Office of Scientific&Technical Information Technical Reports,1999.
[7]Beard B L,Johnson C M.High precision iron isotope measurements of terrestrial and lunar materials[J].Geochimica et Cosmochimica Acta,1999,63:1 653-1 660.
[8]John F Rudge,Ben C Reynold,Bernard Bourdon.The double spike toolbox[J].Chemical Geology,2009,265:420-431.
[9]CHU Zhuyin,YANG Yueheng,GUO Jinghui.Calculation methods for direct internal mass fractionation correction of spiked isotopic ratios from multi-collector mass spectrometric measurements[J].International Journal of Mass Spectrometry,2011,299(2):87-93.
[10]Johnson C M,Beard B L.Correction of instrumentally produced mass fractionation during isotopic analysis of Fe by Thermal Ionization Mass Spectrometry[J].International Journal of Mass Spectrometry,1999,193(1):87-99.
[2]DZ/T 0184.4-1997岩石、矿物铷锶同位素地质年龄及锶同位素比值的测定中华人民共和国地质矿产行业标准[S].北京:中华人民共和国地质矿产部,1997.
[3]Boelrijk N A I M.A general formula for double isotope dilution analysis[J].Chemical Geology,1968,3(4):323-325.
[4]Russell W A,Papanastassiou D A,Tombrello T A.Ca isotope fractionation on the Earth and other solar system materials[J].Geochimica et Cosmochimica Acta,1978,42:1 075-1 090.
[5]Gioia S M C L,Pimentel M M.The Sm-Nd Isotopic Method in the Geochronology Laboratory of the University of Brasília[J]An.Acad.Bras.Ci.,2000,72(2):219-245.
[6]Russ G P.Inter-Laboratory Uranium Double-Spike Experiment[J].Office of Scientific&Technical Information Technical Reports,1999.
[7]Beard B L,Johnson C M.High precision iron isotope measurements of terrestrial and lunar materials[J].Geochimica et Cosmochimica Acta,1999,63:1 653-1 660.
[8]John F Rudge,Ben C Reynold,Bernard Bourdon.The double spike toolbox[J].Chemical Geology,2009,265:420-431.
[9]CHU Zhuyin,YANG Yueheng,GUO Jinghui.Calculation methods for direct internal mass fractionation correction of spiked isotopic ratios from multi-collector mass spectrometric measurements[J].International Journal of Mass Spectrometry,2011,299(2):87-93.
[10]Johnson C M,Beard B L.Correction of instrumentally produced mass fractionation during isotopic analysis of Fe by Thermal Ionization Mass Spectrometry[J].International Journal of Mass Spectrometry,1999,193(1):87-99.