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BACKGROUND: One Rb-Sr certified reference materials (GBW04411) and one Sm-Nd certified reference materials (GBW04419) for geological age, which are potash feldspar and basalt respectively, were produced and certified about 30 years ago. They have only one certified value and their matrices differ from many other geological samples. To better assess the quality of chromatographic separation, measurement procedures and mass spectrometry performance when analyzing Rb-Sr and Sm-Nd, three CRMs which are peridotite, eclogite and granite for Rb-Sr and Sm-Nd analysis were produced, and labelled GBW04139, GBW04140 and GBW04141 respectively.OBJECTIVES: To prepare certified reference materials for analysis of Rb-Sr and Sm-Nd isotopes of different types of rocks.METHODS: Peridotite, eclogite and granite from typical areas in China were used as candidates. Referring to ‘Determinations for isotopes of lead, strontium and neodymium in rock samples (GB/T 17672-1999)’, ‘Determination of Rb-Sr isotopic geological age and Sr isotope ratio in rocks and minerals (DZ/T 0184.4-1997)’, ‘Determination of Sm-Nd isotopic geological age and Nd isotope ratio in rocks and minerals (DZ/T 0184.6-1997)’, Rb, Sr, Sm and Nd were purified by chromatographic separation, and their concentrations were analyzed by ID-TIMS, 87Sr/86Sr and 143Nd/144Nd ratios were determined by TIMS and MC-ICP-MS, respectively.RESULTS: For homogeneity testing of the three CRMs, fifteen bottles of each were randomly selected (from the 200 bottles prepared) for analysis. F-testing was used to study homogeneity. The result was insignificant (1 < F < Fcritical (vamong, vwithin), demonstrating that the three CRMs had very good homogeneity. On the basis of the homogeneity study, the minimum sample required to ensure homogeneity was 1g for Peridotite, and 0.3g for Eclogite and Granite. The long-term stability of the samples was evaluated five times over 26 months. A linear model was used as a basic model for evaluating stability of Rb, Sr, Sm, Nd concentration and 87Sr/86Sr, 143Nd/144Nd. Given that|b1|

BACKGROUND The Sr and Nd isotopic compositions of a sample depend on its initial isotopic ratios, the ratios between the parent nuclide and daughter product, and the decay time. Due to their significance for the tracing of reservoirs, they were widely applied in the geological studies. Traditional cation resin was applied to purify Sr and Nd for isotope analysis, which involved the organic reagent and pH adjustment. The complex chemical procedure was time-consuming. In recent years, the appearance of special resins has made it easy to separate these elements. However, due to the influence of sulfates and other factors, the use of special resins is limited. OBJECTIVES To shorten the chemical purification time of Sr and Nd, and to avoid the damage of sulfate ions on the Sr and REE specific resins, we proposed a new chemical purification method, where multiple columns were utilized. METHODS The method combines cationic resin and special resin to realize the rapid separation of Sr and Nd and can extend the using time of special resin. The experiment uses cationic resin, Sr special resin and LN rare earth special resin to analyze the basalt standard BCR-2. RESULTS The recoveries of Sr and Nd with this method were larger than 90%. The 87Sr/86Sr and 143Nd/144Nd isotope ratios were 0.705016±0.000016 (n=36, 1SD) and 0.512624±0.000012 (n=39, 1SD), respectively, which were in coincidence with the values previously reported by TIMS method within the analytical error. The complied 87Sr/86Sr and 143Nd/144Nd isotope ratios obtained TIMS were 0.705000-0.705023 and 0.512630-0.512650, respectively. The 85Rb/86Sr and 147Sm/144Nd rations of the purified Sr and Nd solution were less than 0.01 and 0.001, respectively. CONCLUSIONS The proposed chemical purification procedure can efficiently separate Rb, Sr, Sm and Nd, and realize the accurate analysis of Sr and Nd isotopes.

Titanium isotopic compositions have been used to elucidate geochemical and cosmochemical processes. Until now, no Ti isotopic reference material has been reported worldwide, which imposes restriction upon analytical method establishment and laboratory quality control. In this paper, a newly prepared Ti isotopic standard solution is introduced. Ti element standard solution offered by the Alfa Company from U.S.A. was chosen as the starting material, based on the comparison of Ti isotopic measurement results of 3 commercially available Ti element standard solutions. The preparation of the new standard solution was strictly followed using the stipulation on reference material of the metrological technical standard of state, including homogeneity and stability tests, and certification analyses. 150 bottles of the solution were prepared, among which 15 bottles were selected randomly for homogeneity test and no detectable heterogeneity was found by F test. The stability inspection through 30 months indicated no significant changes on δTi values. The certified values and uncertainty at the 95% confidence level were shown to be: δ50Ti=-2.23‰±0.14‰, δ49Ti=-1.67‰±0.09‰,δ48Ti=-1.13‰±0.06‰ andδ47Ti=-0.57‰±0.05‰. This newly certified standard solution can be used to calibrate instruments and verify analytical quality in Ti isotope measurements, and compare inter-laboratory data.

A new certified reference material, labelled GSB 04-3258-2015, for use as a 143Nd/144Nd isotope ratio reference has been prepared by the Institute of Geology, Chinese Academy of Geological Sciences, Beijing. Standardization Administration of the People's Republic of China provided the certification for this reference material. This report presents the reference 143Nd/144Nd isotope ratio and supporting production and certification procedures. The reference value was determined by an interlaboratory comparison of results from eleven participating laboratories using MC- TIMS or MC- ICP- MS. The calibration of mass fractionation was conducted by using the exponential law, and the 143Nd/144Nd isotope ratios were normalised to the 146Nd/144Nd isotope ratio value of 0.7219. Isobaric interference of 144Sm on 144Nd was corrected using an interference-free 147Sm/149Sm isotope ratio value for mass fractionation. GSB 04-3258-2015 shows sufficient homogeneity and stability for use as an international isotopic reference material. The certified value was calculated from the unweighted means of the results submitted by the participating laboratories. The 143Nd/144Nd isotope ratio value for GSB 04-3258-2015 is 0.512438, with a combined expanded uncertainty ( k = 2) of 5 × 10−6. Reference material GSB 04-3258-2015 is available upon request from the Institute of Geology, Chinese Academy of Geological Sciences, and may be used for accurate interlaboratory calibration of Nd isotope analysis. [ABSTRACT FROM AUTHOR]