Integrated Extraction Chromatographic Separation of the LithophileElements Involved in Long-Lived Radiogenic Isotope Systems (Rb−Sr, U−Th−Pb, Sm−Nd, La−Ce, and Lu−Hf) Useful in Geochemical andEnvironmental Sciences

International audienceA fast and efficient sample preparation method in view ofisotope ratio measurements is described, allowing the separation of 11elements involved, either as“parent”or as“daughter”isotopes, in sixradiogenic isotope systems used as chronometers and tracers in earth,planetary, and environmental sciences. The protocol is based on smallextraction chromatographic columns, used either alone or in tandem,through which a single nitric acid solution is passed, without anyintervening evaporation step. The columns use commercially availableextraction resins (Sr resin, TRU resin, Ln resin, RE resin, and again Ln resinfor isolating Sr and Pb, LREE then La−Ce−Nd−Sm, Lu(Yb), and Hf, Th,and U, respectively) along with an additional, in-house prepared resin forseparating Rb. A simplified scheme is proposed for samples requiring theseparation of Sr, Pb, Nd, and Hf only. Adverse effects of troublesome majorelements (Fe3+, Ti) are circumvented by masking with ascorbic acid andhydrofluoric acid, respectively. Typical recoveries in the 85−95% range are achieved, with procedural blanks of 10−100 pg,negligible with regard to the amounts of analytes processed. The fractions separated are suitable for high precision isotope ratiomeasurements by TIMS or MC-ICP-MS, as demonstrated by the repeat analyses of several international reference materials ofbasaltic composition for87Sr/86Sr,208,207,206Pb/204Pb,143Nd/144Nd,176Hf/177Hf, and230Th/232Th. Concentration data could beobtained by spiking and equilibrating the sample with appropriate isotopic tracers before the onset of the separation process and,finally, measuring the isotope ratios modified by the isotope dilution process