热电离质谱法测定次纳克级钕同位素比值
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摘要
采用热电离质谱法测定次纳克级钕同位素的比值。应用金属铼带对0.1~0.5ng Nd同位素标准样品进行测定,在不添加任何发射剂或者电离增强剂的条件下,采用特定的聚焦程序,获得了0.4~1V的142 Nd+稳定离子流,持续时间可达30min以上。电流范围在1 700~2 000mA之间时,质量分馏效应缓慢变低稳定。应用此方法对42个0.1~0.5ng La Jolla国际标准样品和18个0.1~0.5ng LRIG-Nd室内参考标准样品进行测定,143 Nd/144 Nd比值分别为0.511 852±0.000 002(2SE)和0.512 201±0.000 003(2SE),与其他报道参考值相符。
Thermal ionization mass spectrometry(TIMS)was applied to the precise measurement of isotopic ratio of sub-nanogram Nd.With the Nd+method and a new type Re ribbon filament,sub-nanogram(0.1-0.5ng)standard samples of Nd were measured.Without adding any emitter or activator wading agents,0.4-1V142 Nd+ion beam was obtained and could last more than 30 minutes under special focusing procedure.With increasing current,the mass fractionation effect tended to lower and more stable in the current range of 1 700-2 000 mA.The proposed method was applied to the analysis of 42 La Jolla international standard samples of 0.1-0.5ng Nd and18LRIG-Nd in-house standard samples of 0.1-0.5ng Nd.143 Nd/144 Nd ratios measured were 0.511 852±0.000 002(2SE)and 0.512 201±0.000 003(2SE),which were in agreement with the reference values reported in literature.
Thermal ionization mass spectrometry(TIMS)was applied to the precise measurement of isotopic ratio of sub-nanogram Nd.With the Nd+method and a new type Re ribbon filament,sub-nanogram(0.1-0.5ng)standard samples of Nd were measured.Without adding any emitter or activator wading agents,0.4-1V142 Nd+ion beam was obtained and could last more than 30 minutes under special focusing procedure.With increasing current,the mass fractionation effect tended to lower and more stable in the current range of 1 700-2 000 mA.The proposed method was applied to the analysis of 42 La Jolla international standard samples of 0.1-0.5ng Nd and18LRIG-Nd in-house standard samples of 0.1-0.5ng Nd.143 Nd/144 Nd ratios measured were 0.511 852±0.000 002(2SE)and 0.512 201±0.000 003(2SE),which were in agreement with the reference values reported in literature.
引文
[1]李潮峰,林杨挺,郭敬辉,等.热电离质谱法超高精度测定142 Nd/144 Nd同位素比[J].分析化学,2010,38(7):989-993.
[2]李潮峰,陈福坤,王芳.采用氧化物方式高精度测量微量样品钕同位素比值[J].地球科学-中国地质大学学报,2008,33(2):243-250.
[3]CHU Zhu-yin,CHEN Fu-kun,YANG Yue-heng,et al.Precise determination of Sm,Nd concentrations and Nd isotopic compositions at the nanogram level in geological samples by thermal ionization mass spectrometry[J].Journal of Analytical Atomic Spectrometry,2009,24:1534-1544.
[4]GRISELIN M,BELLE J C,VAN P C,et al.An improved chromatographic separation technique of Nd with application to NdO+isotope analysis[J].Chemical Geology,2001,172,347-359.
[5]HARVEY J,BAXTER E F.An improved method for TIMS high precision neodymium isotope analysis of very small aliquots(1-10ng)[J].Chemical Geology,2009,258:251-257.
[6]LI Chao-feng,CHEN Fu-kun,LI Xian-hua.Precise i-sotopic measurements of sub-nanogram Nd of standard reference material by thermal ionization mass spectrometry using the NdO+technique[J].International Journal of Mass Spectrometry,2007,266:34-41.
[7]濮巍,赵葵东,凌洪飞,等.新一代高精度高灵敏度的表面热电离质谱仪(Triton TI)的Nd同位素测定[J].地球学报,2004,25(2):271-274.
[8]CARO G,BOURDON B,BIRCK J L,et al.Highprecision 142 Nd/144 Nd measurements in terrestrial rocks:constraints on the early differentiation of the Earth′s mantle[J].Geochimicaet Cosmochimica Acta,2006,70:164-191.
[9]NOBLE S R,LIGHTFOOT P C,SCHARER U.A new method for single-filament isotopic analysis of Nd using in situ reduction[J].Chemical Geology,1989,79:15-19.
[10]SHARMA M,CHEN C.Neodymium isotope fractionation in the mass spectrometer and the issue of142 Nd anomalies in early Archean rocks[J].Precambrian Research,2004,135(4):315-329.
[11]THIRLWALL M F.Long-term reproducibility of multicollector Sr and Nd isotope ratio analysis[J].Chemical Geology,1991,94:85-104.
[12]VANCE D,STONE J O H,ONIONS R K.He,Sr and Nd isotopes in xenoliths from Hawaii and other oceanic islands[J].Earth Planet Science Letter,1989,96:147-160.
[13]AMELIN Y,ROTENBERG E.Sm-Nd systematics of chondrites[J].Earth and Planetary Science Letters,2004,223(3/4):267-282.
[14]ANDREASENA R,SHARMA M.Fractionation and mixing in a thermal ionization mass spectrometer source:implications and limitations for high-precision Nd isotope analysis[J].International Journal of Mass Spectrometry,2009,285:49-57.
[15]CAVAZZINI G.Rayleigh′s distillation law and linear hypothesis of isotope fractionation in thermal ionization mass spectrometry[J].International Journal of Mass Spectrometry,2009,288:84-91.
[16]THIRLWALL M F.High-precision multicollector isotopic analysis of low levels of Nd as oxide[J].Chemical Geology,1991,94:13-22.
[17]杨岳衡,张宏福,谢烈文,等.多接收器电感耦合等离子质谱精确测定钕同位素组成[J].分析化学,2007,35(1):71-74.
[18]钱政,贾果欣,吉小军,等.误差理论与数据处理[M].北京:科学出版社,2013:120-124.
[2]李潮峰,陈福坤,王芳.采用氧化物方式高精度测量微量样品钕同位素比值[J].地球科学-中国地质大学学报,2008,33(2):243-250.
[3]CHU Zhu-yin,CHEN Fu-kun,YANG Yue-heng,et al.Precise determination of Sm,Nd concentrations and Nd isotopic compositions at the nanogram level in geological samples by thermal ionization mass spectrometry[J].Journal of Analytical Atomic Spectrometry,2009,24:1534-1544.
[4]GRISELIN M,BELLE J C,VAN P C,et al.An improved chromatographic separation technique of Nd with application to NdO+isotope analysis[J].Chemical Geology,2001,172,347-359.
[5]HARVEY J,BAXTER E F.An improved method for TIMS high precision neodymium isotope analysis of very small aliquots(1-10ng)[J].Chemical Geology,2009,258:251-257.
[6]LI Chao-feng,CHEN Fu-kun,LI Xian-hua.Precise i-sotopic measurements of sub-nanogram Nd of standard reference material by thermal ionization mass spectrometry using the NdO+technique[J].International Journal of Mass Spectrometry,2007,266:34-41.
[7]濮巍,赵葵东,凌洪飞,等.新一代高精度高灵敏度的表面热电离质谱仪(Triton TI)的Nd同位素测定[J].地球学报,2004,25(2):271-274.
[8]CARO G,BOURDON B,BIRCK J L,et al.Highprecision 142 Nd/144 Nd measurements in terrestrial rocks:constraints on the early differentiation of the Earth′s mantle[J].Geochimicaet Cosmochimica Acta,2006,70:164-191.
[9]NOBLE S R,LIGHTFOOT P C,SCHARER U.A new method for single-filament isotopic analysis of Nd using in situ reduction[J].Chemical Geology,1989,79:15-19.
[10]SHARMA M,CHEN C.Neodymium isotope fractionation in the mass spectrometer and the issue of142 Nd anomalies in early Archean rocks[J].Precambrian Research,2004,135(4):315-329.
[11]THIRLWALL M F.Long-term reproducibility of multicollector Sr and Nd isotope ratio analysis[J].Chemical Geology,1991,94:85-104.
[12]VANCE D,STONE J O H,ONIONS R K.He,Sr and Nd isotopes in xenoliths from Hawaii and other oceanic islands[J].Earth Planet Science Letter,1989,96:147-160.
[13]AMELIN Y,ROTENBERG E.Sm-Nd systematics of chondrites[J].Earth and Planetary Science Letters,2004,223(3/4):267-282.
[14]ANDREASENA R,SHARMA M.Fractionation and mixing in a thermal ionization mass spectrometer source:implications and limitations for high-precision Nd isotope analysis[J].International Journal of Mass Spectrometry,2009,285:49-57.
[15]CAVAZZINI G.Rayleigh′s distillation law and linear hypothesis of isotope fractionation in thermal ionization mass spectrometry[J].International Journal of Mass Spectrometry,2009,288:84-91.
[16]THIRLWALL M F.High-precision multicollector isotopic analysis of low levels of Nd as oxide[J].Chemical Geology,1991,94:13-22.
[17]杨岳衡,张宏福,谢烈文,等.多接收器电感耦合等离子质谱精确测定钕同位素组成[J].分析化学,2007,35(1):71-74.
[18]钱政,贾果欣,吉小军,等.误差理论与数据处理[M].北京:科学出版社,2013:120-124.