Precise determination of Cr, Mn, Fe, Co and Ni concentration by an isotope dilution–internal standardization method employing high resolution MC–ICP–MS

A new determination method for Cr, Mn, Fe, Co and Ni in silicate samples by an isotope dilution–internal standardization method (ID–IS)–high resolution (HR)–MC–ICP–MS has been developed. A silicate sample is dissolved into solution, and a Cr-spike solution is added into an aliquot of the sample solution. Then the solution is introduced into HR–MC–ICP–MS without chemical separation. Concentration of Cr is determined by ID, and those of Mn, Fe, Co and Ni are by ID–IS. Matrix effects were examined in detail, and negligible down to a dilution factor (DF; the weight of the sample solution over that of the sample in the solution) of ∼ 3000 for basalt, and ∼ 104 for peridotite and chondrite within an error range of ± 1%. ID–IS–HR–MC–ICP–MS showed intermediate precision of ∼ 1% for basalt and chondrite, which is comparable to ID–TIMS for Cr, Fe and Ni, and > 10 times better than HR–ICP–MS, suggesting that this method is suitable for precise Mn–Cr and Fe–Ni chronometers.