Potassium isotopic composition of various samples using a dual-path collision cell-capable multiple-collector inductively coupled plasma mass spectrometer, Nu instruments Sapphire

Mass-dependent K isotopic fractionations can be used to trace cosmochemical, geological, and biological processes such as evaporation/condensation, core formation, magmatic processes, weathering, cellular metabolism. However, the application of stable isotopes has been limited by major isobaric interferences from Ar, common on conventional multi-collector inductively-coupled-plasma mass-spectrometer (MC-ICP-MS), particularly for low-K samples. Here, we present a set high-precision data acquired terrestrial rocks, seawater, well lunar meteorite using recently released Nu Sapphire™ MC-ICP-MS that utilizes collision cell minimize Ar based while maintaining remarkably high sensitivity (≈ 2000 V/ppm). The influence several parameters precision accuracy evaluated, including total concentration, intensity mismatch between sample standard, HNO3 molarity presence matrix elements. We found acquire precise accurate little 125 ng K, which represents an improvement factor 10 compared what done previous instruments. 23 previously analyzed samples; these are highly consistent with literature values. On other hand, measurements conditioned 1) close matching standard intensities (a 1% creates 0.02‰ offset 41K/39K ratio), 2) absence Ca Ca/K ratio 0.069‰ ratio). In addition, Rb/K, Na/K, Ti/K Cr/K should also maintained under 2.5% avoid offset. confirm existence significant mass-dependent variations in samples rocks isotopically heavier than rocks. incomparable offered Sapphire opens possibility across wide range diverse applications.