Rapid decomposition of geological samples by ammonium bifluoride (NH ₄ HF ₂ ) for combined Hf‐Nd‐Sr isotope analyses

Rationale Complete decomposition of silicate rock matrices is crucial in determining their isotopic compositions, but acid dissolution a high-pressure steel-jacketed bomb, which has been the only powerful, effective technique thus far, time-consuming and expensive. Rock using ammonium bifluoride (ABF), as described here, viable alternative. Methods Geological reference materials (GRMs) were digested ABF closed Teflon beakers at temperatures 220/230°C convection oven subsequently treated with HNO3. Hf-Sr-Nd separated purified ion-exchange chemistry columns calibrated for 50–2 mg samples. The compositions Sr-Nd measured by Thermal Ionization Mass Spectrometry, while that Hf Multi-Collector Inductively Coupled Plasma both normal 1011 Ω gain 1013 amplifiers. Results Total procedural blanks our protocol are 0.5 ng Sr, 0.2 Nd <25 pg Hf. Test runs GRMs, ranging composition from basic to felsic dissolved ABF, yield accurate 87Sr/86Sr, 143Nd/144Nd 176Hf/177Hf isotope ratios compared those obtained bomb technique. Reproducibilities comparable, on order 10–20 ppm. Our allows combined analyses low-mass (50–2 mg) Conclusions digestion an alternative matrix reproducible Hf-Nd-Sr geological samples within reasonable time (3–4 days), high sample throughput low costs geochemistry environmental sciences.