Miniaturized, rapid separation of neodymium from ultramafic and chondritic samples prior to high precision measurements of 142,143 Nd/ 144 Nd isotope ratios by TIMS

International audienceAn improved method is described for isolating Nd from challenging silicate materials. After a shortdissolution with hydrofluoric acid, the 1–2 gram sample is subjected to a protracted treatment with nitricand hydrochloric acid at mild temperature. Then, the sample is taken up in 15–20 mL of 1 M HNO3.Residualfluorides are isolated by centrifugation, and decomposed with boric acid. Ascorbic acid is addedto reduce Fe(III) to Fe(II) and the solution is loaded onto a small column containing 1.5 mL of TRUextraction chromatography (EXC) resin, to extract the REE + Th and U. The LREEs are stripped by using3 M HCl and directly loaded onto the next, on-line columnfilled with 1 mL of DGA EXC resin whichachieves the separation of Nd from Sm, and from the bulk of Ce and Pr. Neodymium is stripped with0.006 M HCl onto a 1 mL column of LN2 EXC resin for further purification from residual Ce and Pr. Byvirtue of small EXC columns and reagents permitting direct cross-over from a column to the next one,this scheme does not involve evaporation steps, and can be performed in about 12 hours, with good Ndyields and negligible blanks. The method is validated by the analysis of depleted basic and ultra-basicrocks, and a sample of the Allende carbonaceous chondrite. Compared with previous methods used toprocess difficult samples, this protocol is drastically down-scaled, relatively simple to implement, andmuch less demanding in terms of analyst time, reagent volumes, and costs