TY - JOUR

T1 - High precision Fe isotope measurements with high mass resolution MC-ICPMS

AU - Weyer, S.

AU - Schwieters, J. B.

PY - 2003/5/1

Y1 - 2003/5/1

N2 - This study presents a new technique for high precision measurement of iron isotope ratios using high mass resolution MC-ICPMS on the ThermoFinnigan Neptune. A mass resolving power of about 8000-9000 was used to resolve the mass interferences of isobaric polyatomic ions (e.g., 40Ar16O+ on 56Fe+, 40Ar16OH+ on 57Fe+ and 40Ar14N+ on 54Fe+) from the Fe isotopes and to produce "flat top" peak shapes with a plateau width of about 100ppm in mass (Δm/m). The abundance sensitivity was determined to 50ppm contribution of the 40Ar16O+ peak tail on the 56Fe+ peak. This enables Fe isotope measurements with a Fe-isotope/interference ratio of up to 1, without significant contribution from the tail of the interference peak. The performance of the technique was tested by determining the reproducibility and accuracy of synthetic Fe samples and spiked standards against the IRMM014 standard. Various interface setups, including wet and dry plasma techniques, and a wide range of concentrations (from 50ppb to 10ppm) have been used to demonstrate the flexibility, robustness and sensitivity of the technique. An external precision of ca. 0.10‰ for δ56Fe and ca. 0.15‰ for δ57Fe (2 S.D.) was routinely achieved. Measured and calculated delta values between spiked standards and the IRMM014 standard agree within uncertainties. In the investigated concentration range, precision and accuracy are independent of both the sample introduction system and the sample concentration. The new technique presented in this study is a robust and simple method to perform high precision Fe isotope measurements, and it allows to measure much lower sample concentrations compared to previous techniques.

AB - This study presents a new technique for high precision measurement of iron isotope ratios using high mass resolution MC-ICPMS on the ThermoFinnigan Neptune. A mass resolving power of about 8000-9000 was used to resolve the mass interferences of isobaric polyatomic ions (e.g., 40Ar16O+ on 56Fe+, 40Ar16OH+ on 57Fe+ and 40Ar14N+ on 54Fe+) from the Fe isotopes and to produce "flat top" peak shapes with a plateau width of about 100ppm in mass (Δm/m). The abundance sensitivity was determined to 50ppm contribution of the 40Ar16O+ peak tail on the 56Fe+ peak. This enables Fe isotope measurements with a Fe-isotope/interference ratio of up to 1, without significant contribution from the tail of the interference peak. The performance of the technique was tested by determining the reproducibility and accuracy of synthetic Fe samples and spiked standards against the IRMM014 standard. Various interface setups, including wet and dry plasma techniques, and a wide range of concentrations (from 50ppb to 10ppm) have been used to demonstrate the flexibility, robustness and sensitivity of the technique. An external precision of ca. 0.10‰ for δ56Fe and ca. 0.15‰ for δ57Fe (2 S.D.) was routinely achieved. Measured and calculated delta values between spiked standards and the IRMM014 standard agree within uncertainties. In the investigated concentration range, precision and accuracy are independent of both the sample introduction system and the sample concentration. The new technique presented in this study is a robust and simple method to perform high precision Fe isotope measurements, and it allows to measure much lower sample concentrations compared to previous techniques.

KW - High mass resolution

KW - Iron

KW - MC-ICPMS

KW - Stable isotopes

UR - http://www.scopus.com/inward/record.url?scp=0037402534&partnerID=8YFLogxK

U2 - 10.1016/S1387-3806(03)00078-2

DO - 10.1016/S1387-3806(03)00078-2

M3 - Article

AN - SCOPUS:0037402534

VL - 226

SP - 355

EP - 368

JO - International Journal of Mass Spectrometry

JF - International Journal of Mass Spectrometry

SN - 1387-3806

IS - 3

ER -