A precise and accurate analytical method for determination of osmium isotope ratios at the 1–15 pg level by using a MC-ICP-MS equipped with sparging introduction and high-sensitivity discrete dynode-type ion-counting detectors

Abstract

Properly calibrated discrete dynode SEM ion-counting detectors and minimization of blank Os by an improved vial-cleaning method enables Os isotope analysis at the 1–15 pg level with high accuracy and precision.

Pelagic responses to oceanic anoxia during the Carnian Pluvial Episode (Late Triassic) in Panthalassa Ocean

“…Thus, the memory effect due to the previous sample was quickly removed by the Ar gas flushing with less than 30 s. In this case, the memory effect due to analysis of a previous sample was quickly removed by Ar gas flushing for < 30 s. After the Os isotope measurement, the sample solutions were evaporated on a hotplate at 140 °C to remove the remaining Os. Rhenium was then purified using a two-step column separation procedure with anion exchange resin (Muromac AG 1-X8) following the methods of Nozaki et al 65 , Ohta et al 68 , and Morgan et al 70 . Rhenium isotope ratios were measured by MC–ICP–MS with solution introduction into the glass torch, using the Ir standard addition method for external mass bias correction by using 193 Ir/ 191 Ir = 1.68097 (Refs.…”

“…Rhenium isotope ratios were measured by MC–ICP–MS with solution introduction into the glass torch, using the Ir standard addition method for external mass bias correction by using 193 Ir/ 191 Ir = 1.68097 (Refs. 68 , 71 ). The Re blank was 0.44 pg, and the Os blanks were 0.12 and 0.09 pg, with 187 Os/ 188 Os ratios of 0.157 and 0.221, respectively.…”

“…Johnson Matthey Company (JMC) Os standard solutions ( 187 Os/ 188 Os = 0.106838 ± 0.000015) 65 containing 40 pg of total Os were also prepared and processed in each analytical batch to assess the data accuracy. The Os isotope ratios were determined by MC-ICP-MS combined with the sparging introduction of OsO 4 gas molecules into the ICP glass torch [65][66][67][68] , using Faraday cups (FCs) for manganese ore samples and compact discrete dynode (CDD) multi-ion-counting detectors for blank and chert samples. Different yields among three CDDs was corrected by in-run cross-calibration by monitoring 190 Os with a quadratic drift correction 68 and instrumental mass bias within the MC-ICP-MS was internally corrected by normalizing with 192 Os/ 188 Os = 3.08271 (Ref.…”

“…The Os isotope ratios were determined by MC-ICP-MS combined with the sparging introduction of OsO 4 gas molecules into the ICP glass torch [65][66][67][68] , using Faraday cups (FCs) for manganese ore samples and compact discrete dynode (CDD) multi-ion-counting detectors for blank and chert samples. Different yields among three CDDs was corrected by in-run cross-calibration by monitoring 190 Os with a quadratic drift correction 68 and instrumental mass bias within the MC-ICP-MS was internally corrected by normalizing with 192 Os/ 188 Os = 3.08271 (Ref. 69 ) when using both CDDs and FCs.…”