多接收双聚焦等离子体质谱法测定高精度同位素比

Determination of Isotopic Ratio by Multi-collector Double-focusing Inductively Coupled Plasma Mass Spectrometry

采用 VG Axiom型多接收双聚焦等离子质谱仪 ( MC-ICPMS)测定 Nd、Pb、U同位素比值 ,应用指数公式对测定的结果进行质量歧视校正。结果表明 :测定参考物质 Ames Nd获得的钕同位素比值为 14 3 Nd/14 4 Nd=0 .5 1 2 1 44± 0 .0 0 0 0 1 5 (确认值为 0 .5 1 2 1 3 5 )、14 5Nd/14 4 Nd=0 .3 4841 7± 0 .0 0 0 0 1 9(确认值为 0 .3 4841 8) ;测定参考物质 NIST SRM981获得的铅同位素比值为 2 0 8Pb/2 0 4Pb=3 6.71 1 4± 0 .0 0 81、2 0 7Pb/2 0 4Pb=1 5 .4886± 0 .0 0 3 8、2 0 7Pb/2 0 6Pb=0 .91 44 5 6± 0 .0 0 0 0 3 9、2 0 6Pb/2 0 4Pb=1 6.93 82± 0 .0 0 3 1、2 0 8Pb/2 0 6Pb=2 .1 660 1± 0 .0 0 0 1 6;测定参考物质 NIST SRM 0 1 0获得的铀同位素比值为 2 3 4 U/2 3 8U =0 .0 0 0 0 5 46±0 .0 0 0 0 0 0 3 (确认值为 0 .0 0 0 0 5 46)

Isotopic ratios of Nd, U and Pb were measured using VG Axiom multi-collector double-focusing inductively coupled plasma mass spectrometry(MC-ICPMS). The correction for mass discrimination was based on the exponential law. And present measurements of Ames Nd and NIST SRM981 and NIST SRM010 standards were performed. The results show the isotopic ratio for 143Nd/ 144Nd is 0.512 144±0.000 015, and 145Nd/ 144Nd for 0.348 17±0.000 019 (2σ) for Ames Nd. The isotopic ratio for 208Pb/ 204Pb is 36.711 4± 0.0081, 15.488 6±0.003 8 for 207Pb/ 204Pb, and 0.914 456±0.003 9 for 207Pb/ 206Pb for NIST SRM981. The isotopic ratio for 234U/ 238U is 0.000 054 6±0.000 000 3 for NIST SRM010.