Precise Measurement Re Concentration of Natural Rock Sample by MC-ICPMS Using Iridium to Correct for Mass Fractionation

This study reported a measurement method of high-precision rhenium isotope ratio, ¹⁸⁷Re/¹⁸⁵Re, and Re concentration of natural rock samples were measured by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) through measuring the amount of fractionation on admixed lridium. It recognizes that the mass fractionation of MC-ICPMS appears to follow the exponential law, and the fractionation coefficients of Re and Ir are not identical, but the ratio of f_Re/f_Ir is constant during an analytical session. Thus, this constant ratio can be used to calculate the value of f_Re according to known value f_Ir. Replicate analyses of both Re natural standard and ¹⁸⁵Re enriched spike determined by MC-ICPMS are consistent with those measured by negative thermal ionization mass spectrometry (N-TIMS). ¹⁸⁷Re/¹⁸⁵Re ratios of the Re natural standard is 1.674 3±0.000 1(2σ, n=25）. The value is indistinguishable within analytical uncertainty from the value adopted by IUPAC (1.674 0±0.001 1), and is also in agreement with those measured by N-TIMS (1 675 5±0.001 4) . In addition, the precise and accurate are improved by using this empirical correction technique. The Re concentration of the natural rock samples are reasonable agree with those measured by N-TIMS.