• The Journal of the Petrological Society of Korea
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• v.10 no.3
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• pp.157-171
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• 2001

This study investigated the effects of Pb/Tl ratio, Pb concentration and concomitant matrix elements on the measurement of Pb isotope ratios using multi-collector ICP/MS (AXIOM MC model). Accuracy and reproducibility of Pb isotope ratios in NBS 981 solution were estimated for 42 data measured from March to August 2001. Pb isotopes measured in rocks, bronzes and sediments were compared to data measured by TIMS. Reproducibilities for $^{206}Pb/^{204}Pb,\; ^{207}Pb/^{204}Pb,\;and\;^{208}Pb/^{204}Pb$ ratio were about 500 ppm (2sd) and for $^{207}Pb/^{206}Pb$\;and\;^{208}Pb/^{206}Pb$ were 100~200 ppm for 200 ng of Pb in NBS 981 solution. The optimum conditions for the analysis of Pb isotope ratios with AXIOM MC for best accuracy and reproducibility were defined as follows; 1) Pb/Tl ratio is about 10 2) Pb concentration is about 100 ng/ml 3) correction for mass discrimination is performed by exponential law using 2.3887 of $^{205}Tl/^{203}Tl$ and Pb mass fractionation factor empirically obtained from $ln(^{208}Pb/^{206}Pb)-ln(^{205}Tl/^{203}Tl)$ relationship. The sample data measured with MC/ICP/MS for acid-digested and chemically separated rock samples, and acid-digested bronze samples and sediment samples coincide with those of TIMS within analytical errors. Therefore, MC/ICP/MS is a rapid analytical technique for Pb isotope ratios with the similar precision compared with TIMS.