A new synthesis scheme of pyrite and chalcopyrite reference materials for in situ iron and sulfur isotope analysis using LA-MC-ICP-MS

Abstract

Microanalysis of Fe and S isotopes in sulfides by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) has been used as an important tool to identify the material sources...

Tianyu-Py pyrite: a new natural reference material for micro-beam determination of iron isotopic ratios

“…The synthesized pyrite materials PAS-Py600 and natural pyrite Aa018 yielded δ 56 Fe values of 0.18 ± 0.13‰ (2SD, n = 25) and 0.60 ± 0.13‰ (2SD, n = 25), respectively, in good agreement with the recommend values. 59,60 Using Tianyu-Py pyrite as the bracketed standard will, therefore, allow a simple and rigorous comparison of results generated in different laboratories. In addition, an increasing number of studies have shown the significant variability of δ 56 Fe values (∼6‰) in hydrothermal pyrite 38,45 and diagenetic pyrite, 19,34 which is obviously beyond the analytical uncertainty of LA-MC-ICP-MS using a laser spot size of 16 μm.…”

“…The press synthesized pyrite material PAS-Py600 was used as an external standard and the international Fe isotopic standard IRMM-014 (pure iron, 99.9%) from the Institute for Reference Materials and Measurements (IRMM) of the European Commission was used as the quality control sample for in situ Fe isotope analysis. 60 The standard and reference materials were measured before every 10 sample analyses for drift monitoring. The data reduction for LA-MC-ICP-MS analysis was conducted using ISO-Compass software.…”

“…The LA-MC-ICP-MS Fe isotope measurements were performed at high mass resolution (M/DM z 9000, 5-95% peak side width denition) to resolve molecular interference of argon nitrides and argon oxides on Fe isotopes. 70 The detector array of Faraday cups is set to acquire the ion beams of 53 Cr, 54 Fe, 56 Fe, 57 Fe, 58 Fe, and 60 Ni. Cr and Ni are monitored and used for correction of the isobaric interference on 54 Fe and 58 Fe.…”

“…Iron isotopic compositions were measured by the standardbracketing method using a Neptune-Plus at USTC. 53 Cr, 54 Fe, 56 Fe, 57 Fe, 58 Fe, and 60 Ni were measured in a static mode on the L3, L1, H1, H2, and H4 Faraday cups, respectively. The Fe isotopic results are expressed as deviations of an iron isotopic ratio of a sample from that of the reference material IRMM-014 in per mil: d i Fe (&) ¼ [( i Fe/ 54 Fe) sample /( i Fe/ 54 Fe) standard À 1] Â 1000, i ¼ 56, 57.…”

“…Laser ablation MC-ICP-MS (LA-MC-ICP-MS) and secondary ion mass spectrometry (SIMS) are powerful micro-beam techniques for in situ Fe isotopic analyses in pyrite. 34,35,[55][56][57][58][59][60] The micro-beam technique is capable of resolving Fe isotopic variations between natural minerals commonly present as thin lamellae in iron meteorites, micron scale phases in sedimentary, and zonation in hydrothermal deposits. However, both LA-MC-ICP-MS and SIMS analyses generate isotopic ratios that have been fractionated during the examinations, and this fractionation is matrixdependent (e.g., ref.…”