Analysis of a rhenium-osmium solid-solution spike by inductively coupled plasma mass spectrometry

Abstract

The rheniumosmium decay scheme (187Re --t 1870s) offers a unique opportunity t o investigate the genesis of, and directly date, ultramafic rock, sulphide and platinum ore deposits. Inductively coupled plasma mass spectrometry (ICP-MS) is a viable method for 0 s isotopic analysis as it provides the high temperatures necessary t o ionise 0s. The sample can be introduced into the ICP mass spectrometer either by conventional nebulisation or by distillation using an 0 s "generator." Generator-mode analysis is superior t o nebulisation because (i) the total number of counts is two orders of magnitude higher for a given sample size and (ii) 0 s oxidises readily t o volatile OsOs, which has a boiling-point lower than most Re compounds, so that 0 s can be efficiently separated from 187Re. The importance of 0 s loss during sample preparation was minimised by combining the sample powder with a powdered Re -0 s isotopic spike prior t o any chemical treatment. The spike is in a nickel sulphide matrix and was made by a thioacetamide co-precipitation of Os, Re and Ni followed by a fire assay. The 1900s/'9*0s ratio in this preparation is 51.5 k 0.9, the 187Os/188Os ratio is 0.063 2 0.006 and the 185Re/187Re ratio is 17.04 2 0.41. These values are within the error limits quoted by the Oak Ridge National Laboratory and Techsnabexport, the suppliers of the metallic spikes. Parameters that significantly influence the 0 s analyses include the oxidising agent and the run temperature. The oxidising agent H5106 is preferred t o H202 or HNOB as it has the highest electrode potential, provides a prolonged, consistent reaction and is more stable when stored. Chilling the sample and the H5106, initially retards uncontrolled Os04 emission. Heat applied later in the run releases Os04 and helps maintain a high count rate. Thus, Os04 can be generated in a steady, controllable and reproducible manner.

Isotopic evidence for a single impact melting origin of the Sudbury Igneous Complex

“…For each Re-Os analysis, approximately 1 g of ore was mixed with 5 mg of a mixed Re-Os spike in solid solution in a nickel sulfide matrix (Richardson et al, 1989). This mixture was dissolved in warm 5M nitric acid in a covered beaker, and after the reaction was complete (about 3 days later), the undissolved silicate residue was filtered off and weighed.…”

Simultaneous Detection of Ruthenium and Osmium by Photochemical Vapor Generation-Inductively Coupled Plasma-Mass Spectrometry

“…The sensitivity obtained by flame atomic absorption spectrometry was improved by a factor of 60, and the limit of detection (LOD) was 0.05 μg mL –1 . As for Os, the generation of volatile OsO 4 used to be achieved by strong oxidizing agents, such as HNO 3 , H 2 O 2 , H 5 IO 6 , and K 2 Cr 2 O 7 . However, these oxidation reactions can be time-consuming and difficult to be combined for online detection.…”

High-efficiency photooxidation vapor generation of osmium for determination by inductively coupled plasma-optical emission spectrometry

“…The volatility (boiling point: 130 C) of osmium tetraoxide has long been used to separate osmium from a matrix for analytical practices. 15,[28][29][30][31][32][33][34][35][36][37][38] In these studies, the generation of volatile osmium tetraoxide is usually achieved by using a large amount of strong oxidizing agents, such as HNO 3 , 32,37 H 2 O 2 , 31 H 5 IO 6 28,32,33 and K 2 Cr 2 O 7 . 15 In our previous study, we have realized the generation of osmium tetraoxide without any oxidant based on a novel solution cathode glow discharge (SCGD) induced vapor generation method.…”