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...

This work evaluates the use of femtosecond laser ablation multiple collector inductively coupled plasma mass spectrometry (fs-LA-MC-ICP-MS) for Zr isotopic analysis in zircons. The mass fractionation caused by instrumental mass discrimination was corrected by a combination of internal correction using Sr as an internal standard (coming from a NIST SRM 987 standard solution) and external correction using a matrix-matched standard. Several important instrument parameters were investigated, such as the effect of the addition of N2 and “wet” plasma condition, the mass fractionation behaviors between Zr isotopes and Sr isotopes, the position effect in laser ablation cell and the effect of laser ablation parameters (laser spot size and energy density). The Zr isotope compositions of seven zircons (GJ-1, 91500, Plešovice, Rak-17, Paki, Aus and Mala) were determined by the developed fs-LA-MC-ICP-MS and thermal ionization mass spectrometry (TIMS). Our fs-LA-MC-ICP-MS results for Zr isotope compositions agreed with TIMS analyses within analytical uncertainties, indicating the presented method is a suitable tool to resolve isotopic zoning in natural zircons. The results also suggest that GJ-1, 91500, Plešovice, Paki, Aus and Mala had the homogenous Zr isotope composition and could be considered as the potential candidates for the Zr isotope analysis in zircons, except Rak-17 which presented the large Zr isotope variation.

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A new synthetic method has been used to prepare sulfide reference materials for the in situ analysis of PGEs and S–Pb isotopes. The results indicate that the hydrothermal synthesis of the nanoparticles can serve as a potentially effective approach for the preparation of microanalysis reference materials.

Using boron as a test analyte, laser ablation (LA) solution sampling multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is proposed and validated as a fast method for isotopic analysis in natural liquids and digested samples without any prior purification process. We demonstrated that the solution reference standard can be used as a bracketing standard for in situ δ 11 B analysis in solids. Based on a sensitivity enhancement of 8-to 9-fold, all testing solutions were diluted in a 5% (v/v) NH 3 •H 2 O instead of classical 2% (v/v) HNO 3 . With a discrete and minimal sample solvent loading by the LA sampling strategy, it produces nearly "dry" plasma conditions that tolerate the sample matrix remarkably. The memory effect, one of the most difficult challenges in boron analysis, was dramatically eliminated with only 15 s wash time; thus, each analysis took less than 100 s. No significant matrix effects were observed for varying 50−100% boron concentrations in the samples and varying 20−60% NH 3 •H 2 O matrix used for the dilution, as well as for samples doped with a 1/100 synthetic seawater matrix. The external precision of δ 11 B measurements in NIST 951a was ± 0.30‰ (2SD). Good agreement with the values described in literature studies was achieved for δ 11 B measurements in eight geological reference materials, with precisions between 0.4 and 0.7‰ (2SD), confirming the accuracy of the proposed method. The proposed method offers advantages of simple sample preparation, fast analysis, and little use of chemical reagents.

The Fe isotopes of bulk Fe sulfides have become useful tracers for understanding geochemical conditions and processes ubiquitously involving Fe during both biological and non-biological processes under various conditions. However,...

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