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Interest in studying zirconium (Zr) stable isotopic fractionation in both low and high-temperature environments has increased significantly in recent years. Multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) is the preferred technique for stable Zr isotope analysis due to its low sample consumption and high precision. However, the multi-column separation steps required to remove interferences and meet the stringent matrix requirements for Zr isotopes during MC-ICP-MS testing typically make the sample preparation process time-consuming. Here, we present a new, simple, and efficient single-pass chromatographic exchange technique for the chemical isolation of Zr from complex sample matrices. This new separation protocol is based on DGA resin and consists of only three elution steps and two types of acid eluents (15 mL 7 mol L−1 HNO3 and 5 mL 3 mol L−1 HNO3 + 0.1 mol L−1 HF), which afford straightforward separation of Zr with high yield, good purity, and low blank levels. Zr isotope ratios were measured using Neptune Plus MC-ICP-MS with the 91Zr–96Zr double spike in combination with standard–sample bracketing for mass bias correction. The validity of the proposed method is demonstrated by analyzing eight geological reference materials (including BCR-2, which has an extremely high Mo content of ∼248 μg g−1) with satisfactory results that are in good agreement with published values. Based on repeated analyses of pure standard solutions and geological reference materials, the long-term measurement reproducibility is better than ±0.048‰ for δ94Zr. Therefore, the proposed method can be used for the rapid and efficient determination of stable Zr isotope ratios in geological samples. [ABSTRACT FROM AUTHOR]

A time-saving and highly efficient chemical separation procedure to isolate Zn and Mo from various geological samples is developed, which is based on a single pass of a double-stack column. The first column, filled with AG MP-1M resin (100–200 mesh, Bio-Rad), quantitatively removed matrix and interference elements from sample matrices; while the second column, filled with the DGA spec resin (50–100 μm, Eichrom), further isolated Zn and Mo from sample matrices. The proposed protocol was time-saving (50% column running time) and afforded efficient separation and quantitative recovery (more than 96% and 92% for Zn and Mo, respectively) from complex sample matrices of three geological reference materials W-2a, GSR-1 and GSR-2. Both Zn and Mo isotope ratios in the purified Zn and Mo solutions were determined by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) with the use of the combined standard-sample bracketing and internal normalization (C-SSBIN) method and double-spike method, respectively, for mass bias correction. In addition, the effects of two cone combinations and three mass bias correction methods on Zn isotopic analysis were investigated. The results show that the jet + X cone and the C-SSBIN method with Cu as the internal standard provided high accuracy and precision Zn isotope ratio measurements. Zn and Mo isotope ratios were measured in thirteen geological reference materials for the validation of the feasibility and effectiveness of the proposed method with satisfactory results in this study. [ABSTRACT FROM AUTHOR]

A new analytical method for the accurate and precise determination of stable zirconium isotope ratios in geological materials by thermal ionization mass spectrometry (TIMS) is presented. Isobaric interference from Mo was largely eliminated during filament heating and further reduced by off-line Mo interference correction. This methodology allows the complete elimination of Mo interference even with a Mo/Zr ratio up to 1. Separation of Zr from natural sample matrices was achieved by using a single DGA resin column with a small usage of acids (15 mL of 7 mol L−1 HNO3 and 3 mL of 1 mol L−1 HF). A 91Zr–96Zr double spike was admixed with samples before digestion, which enabled the correction of isotope fractionation that could occur during column separation and mass spectrometry measurement. The long-term measurement reproducibility of δ94Zr is generally better than ±0.06‰ (uncertainty represented by two standard deviations, hereinafter referred to as 2 SD), assessed by repeated analyses of Zr standard reference NIST SRM 3169 and eleven geological reference materials. The Zr isotope ratios of geological reference materials BHVO-2 and AGV-2 obtained in this study are consistent with the reported values measured by MC-ICP-MS, confirming the accuracy of the proposed method. This new method greatly simplifies the chemical separation process and is particularly suitable for Zr isotope analysis of complex matrix (especially for high Mo) samples. [ABSTRACT FROM AUTHOR]