硅同位素标准物质的研制

本文所研制的硅同位素标准物质为：ＧＴＢ１，选用震旦亚界长城系常州沟组石英砂岩中的石英；ＧＴＢ２，选用上海试剂一厂生产的高纯二氧化硅试剂。２个标准物质均按国家计量技术规范统一标准物质〈ＪＪＧ１００６８６〉的规定，用ＳｉＦ４法进行了均匀性检验及定值分析工作。结果表明其硅同位素组成均匀，定值准确，并获得了ＧＴＢ１标准物质的δ３０ＳｉＮＢＳ２８（‰）为－０．０２±０．１０，ＧＴＢ２标准物质的δ３０ＳｉＮＢＳ２８（‰）为－２．６８±０．１０。经两年多的稳定性检查，硅同位素值无变化。     

Certification of ERM‐EB400, the First Matrix Reference Material for Lead Isotope Amount Ratios,and ERM‐AE142, a Lead Solution Providing a Lead Isotopic Composition at the Edge of Natural Variation

Lead isotope amount ratios are commonly used in diverse fields such as archaeometry, geochemistry and forensic science. Currently, five reference materials with certified lead isotope amount ratios are available, namely NIST SRM 981, 982 and 983, GBW‐04442 and NMIJ 3681‐a. Only NIST SRM 981 and NMIJ 3681‐a have approximately natural isotopic compositions, and NIST SRM 981 is predominantly used for correcting mass discrimination/mass fractionation in the applied mass spectrometric procedures. Consequently, there is no other certified reference material available to be used for validation and/or quality control of the analytical procedures applied to lead isotope amount ratio measurements. To fill this gap, two new reference materials have been produced and certified for their lead isotope amount ratios. For both certified reference materials, complete uncertainty budgets have been calculated and SI traceability has been established. This provides the users with independent means for validating and verifying their analytical procedures and for conducting quality control measures. ERM‐EB400 is a bronze material with a nominal lead mass fraction of 45 mg kg^?1 and certified lead isotope amount ratios of n(²⁰⁶Pb)/n(²⁰⁴Pb) = 18.072(17) mol mol^?1, n(²⁰⁷Pb)/n(²⁰⁴Pb) = 15.578(18) mol mol^?1 and n(²⁰⁸Pb)/n(²⁰⁴Pb) = 38.075(46) mol mol^?1 with the associated expanded uncertainties (k = 2) given in brackets. ERM‐AE142 is a high‐purity solution of lead in 2% nitric acid with a nominal mass fraction of 100 mg kg^?1 and certified Pb isotope amount ratios of n(²⁰⁶Pb)/n(²⁰⁴Pb) = 21.114(17) mol mol^?1, n(²⁰⁷Pb)/n(²⁰⁴Pb) = 15.944(17) mol mol^?1 and n(²⁰⁸Pb)/n(²⁰⁴Pb) = 39.850(44) mol mol^?1 with the associated expanded uncertainties (k = 2) given in brackets. Both materials are specifically designed to fall within the natural lead isotopic variation and to assist users with the validation and verification of their analytical procedures. Note that while one of these reference materials requires the chemical separation of Pb from its matrix (ERM‐EB400), the other does not (ERM‐AE142). As additional information, δ^208/206Pb_{NIST SRM981} values are provided for both materials. For ERM‐AE142, a delta value of δ^208/206Pb_{NIST SRM981} = ?28.21(30)‰ was obtained, and for ERM‐EB400, a delta value of δ^208/206Pb_NIST SRM981= ?129.47(38)‰ was obtained, with the associated expanded uncertainties (k = 2) given in brackets.     

河流沉积物多环芳烃标准样品的制备与定值

多环芳烃环境标准样品是保证多环芳烃环境监测和污染调查数据可靠性以及不同实验室间分析数据可比性必不可少的计量工具。美国NIST、欧盟IRMM、英国LGC等研究机构已有沉积物多环芳烃环境标准样品,但浓度水平大部分集中在mg/kg浓度水平,与我国当前的污染水平存在一定差距,难以满足痕量分析(μg/kg)质量保证与质量控制的要求。而我国受天然基体标准样品制备技术和定值分析技术的制约,尚没有研制沉积物多环芳烃环境标准样品。本文研制了适合我国多环芳烃环境监测和科学研究需要的河流沉积物标准样品。沉积物样品采集自松花江哈尔滨段流域,经过自然阴干、研磨、筛分、混匀和灭菌等加工处理,分层随机抽取15瓶样品对16种多环芳烃进行均匀性研究,结果表明样品均匀性良好。在30℃避光保存条件下,采用线性模型进行稳定性研究,标准样品在16个月稳定性检验期间未发现不稳定变化趋势。11家实验室对该河流沉积物标准样品采用气相色谱-质谱法和液相色谱法进行联合定值,经统计分析处理评定出14种多环芳烃的标准值和不确定度,并给出2种多环芳烃的参考值,特性量值在6.9~158 μg/kg之间,不确定度在1.5~25 μg/kg之间,可以满足多环芳烃痕量分析质量保证与质量控制的要求。该标准样品被批准为国家标准样品,填补了国内此类标准样品和标准物质空白,已成功应用于土壤和沉积物样品中多环芳烃的监测,可为进一步开展有机污染物环境基体标准样品研制提供参考和借鉴。     

钕同位素比值~(143)Nd/~(144)Nd标准溶液研制

钕同位素比值(~(143)Nd/~(144)Nd)是Sm-Nd同位素方法的关键量值,由于被测样品的~(143)Nd/~(144)Nd比值变化范围很小,所以对~(143)Nd/~(144)Nd比值测试的精准度要求很高(精度优于0.005%)。为了获得高精度和高准确度的测试数据,分析过程中所用Nd同位素标准物质起着重要作用。以往的Nd同位素标准物质都是氧化钕,经过近三十年有的已消耗殆尽。本文阐述了钕同位素比值~(143)Nd/~(144)Nd标准溶液的研制,经检验标准溶液的均匀性和稳定性良好,由11家实验室协同定值,采用MC-TIMS和MC-ICP-MS方法测定~(143)Nd/~(144)Nd,确定了Nd同位素标准溶液的特性值~(143)Nd/~(144)Nd=0.512438,不确定度为5×10-6。此标准溶液于2015年5月获得国家标准样品证书(批号为GSB 04-3258—2015),可被用于地质、资源、海洋、环境、考古等多种样品~(143)Nd/~(144)Nd比值测定时的仪器校准和分析过程的质量监控。     

距今7Ma以来甘肃灵台剖面 Nd和 Sr同位素特征

测定了 7 Ma B.P.以来灵台剖面红粘土和黄土-古土壤序列的酸不溶物 Sr和 Nd同位素组成.样品酸不溶物 87Sr/86Sr变化可明显分为两个阶段.第一个阶段,从 7 Ma B.P.到 2.5 Ma B.P.,为红粘土层,酸不溶物 87Sr/86Sr稳定位于高值,反映了东亚冬季风处于相对平稳的弱势.第二个阶段,从 2.5 Ma B.P.到现在,酸不溶物 87Sr/86Sr呈下降趋势,波动加强,反映了东亚冬季风不断增强,并且冬季风和夏季风交替变化加强. 7 Ma B.P.以来灵台剖面红粘土和上覆的黄土-古土壤的 Nd同位素组成一致,并揭示 7 Ma B.P.以来,北太平洋中部沉积物与黄土高原黄土都来自相同的物源区.     

High-precision Measurements of the 143Nd/144Nd Isotope Ratio in Certified Reference Materials without Nd and Sm Separation by MC-ICP-MS

A precise and accurate method for the determination of 143 Nd/144 Nd isotope ratio without Nd and Sm separation by multiple collector inductively coupled plasma mass spectrometry is demonstrated in this paper.     

Rhenium‐Osmium Isotope Measurements of Geological Reference Material BIR‐1a: Evaluation of Homogeneity and Implications for Method Validation and Quality Control

To evaluate the homogeneity of geological reference material BIR‐1a (basalt; United States Geological Survey, USGS) for Re‐Os isotopic studies at the 0.2–1.0 g test portion size level, sixty‐three precise measurement results of Re and Os mass fractions and isotope amount ratios were obtained over an 18‐month period. These data reveal that the reference material has higher Re (0.691 ± 0.022 ng g^?1, 2s, n = 63) and lower Os mass fractions (0.343 ± 0.089 ng g^?1, 2s, n = 63) than UB‐N (serpentinite, CRPG) and is homogeneous in ¹⁸⁷Os/¹⁸⁸Os isotope amount ratio (0.13371 ± 0.00092, 2s, n = 63) at the 0.2–1.0 g test portion size level. The results are essentially consistent with previous views indicating that BIR‐1a gives precise measurement results for Re‐Os isotope amount ratio measurements at the 1 g test portion size level (Ishikawa et al., Chemical Geology, 2014, 384, 27–46; Meisel and Horan, Reviews in Mineralogy and Geochemistry, 2016, 81, 89–106). Based on these new Re‐Os data and previous studies, we propose BIR‐1a as a useful reference material that can be used in method validation and quality control and interlaboratory comparisons for studies dealing with mafic geological samples at test portion sizes of > 0.4 g.     

黑色页岩铁同位素标准物质的研制

本文选择宜昌三峡地区九龙湾剖面采集的黑色页岩作为黑色页岩Fe同位素备选标准物质,命名为CAGS-BS.使用单因素方差分析法对CAGS-BS进行均匀性检验;使用t检验对其在24个月中四次分析的数据进行长期稳定性的检验,结果显示均匀性和稳定性良好,满足标准物质的要求.黑色页岩Fe同位素标准物质采用多家实验室协作定值的方法确定特征量值.协作定值的单位包括:中国地质科学院地质研究所,中国科学技术大学,中国地质大学(北京),天津大学和中国科学院广州地球化学研究所.剔除了可疑值之后的数据符合正态分布,可以采用算术平均法进行标准物质的定值.标准物质不确定度由协作测定的不确定度分量(uchar)、批内瓶间差异引起的不均匀性不确定度分量(ubb')和实验室保存引起的长期不稳定性不确定度分量(ults)共同确定,总不确定度为扩展不确定度,包含因子(k)等于2.得到CAGS-BS的特征值及不确定度为:δ56FeIRMM-014/‰=0.10±0.04.该标准物质可用于黑色页岩样品的化学流程评价和验证、质谱仪的校正及整个过程的分析质量控制.     

国际同位素参考物质的定值和原子量标定

同位素参考物质是同位素地质测量的"砝码".其同位素组成是同位素测量的基本参数.国际同位素参考物质的建立与定值已有五十多年的历史,其中经历了许多成功与曲折.在20世纪80年代后,国际同位素参考物质的建立与定值进入了健康发展的新时期.在国际原子能机构等国际组织的组织和指导下,许多研究人员积极参与,逐步建立了一批应用广泛的同位素参考物质.采用实验室对比测量和同位素绝对比值测量等方法对这些物质的同位素组成进行了准确定值.这些成果对统一同位素测量的基准和尺度,保证同位素测试数据在国际范围内的可比性起到了巨大的推动作用.同时,对元素原子量标定,乃至阿伏伽德罗常数等基本常数的标定也起了重要作用.     

利用MC-ICPMS精确测定143Nd/144Nd和Sm/Nd比值

多收集器等离子体质谱(MCICPMS)用于分析SmNd同位素时,质量分馏系数(β)与同位素的质量数呈线性关系.可以采用两种方法进行质量分馏校正:双分馏系数内部校正法(DFIC)和单分馏系数外部校正法(SFEC).采用DFIC法,对国际标样ShinEtsuJNdi1和实验室标样NdGIG进行了为期五个月的143Nd/144Nd比值测量统计,结果分别为0.512120±0.000012(2σSD)、0.511532±0.000013(2σSD).采用SFEC法,对NdGIG标样的测量统计结果为0.511525±0.000015(2σSD).两种方法的测量结果在分析误差范围内与其推荐值或TIMS测量值完全一致.对加Ce和Sm的NdGIG混合溶液分别进行了Ce和Sm对143Nd/144Nd比值分析的干扰校正研究和Sm/Nd比值测量,结果显示,143Nd/144Nd比值分别与Ce/Nd、Sm/Nd测量值呈线性关系,Sm/Nd测量值与其质量比值亦呈很好的线性关系.这表明利用MCICPMS可以快速精确地测定存在Ce、Sm干扰的样品的143Nd/144Nd比值,同时可获得精确的Sm/Nd比值,而无需加入稀释剂.这就使直接测定地质样品的SmNd等时线年龄成为可能.     

土壤中总有机碳环境标准样品研制

土壤环境标准样品是土壤生态环境监测质量控制的重要技术工具.目前,土壤中总有机碳环境标准样品仍为中国环境标准样品体系的空缺,特别是配套燃烧氧化-非分散红外法的土壤标准样品一直未曾问世.本文以有机碳含量较高的农用地土壤为原材料,经干燥、研磨、混匀、装瓶、灭菌等加工步骤,制备获得土壤中总有机碳环境标准样品.分层随机抽取10瓶...     

Titanium Isotope Analysis of Igneous Reference Materials using a Double-spike MC-ICP-MS Method

Ti separation was achieved by ion-exchange chromatography using Bio-Rad AG 1-X8 anion-exchange and DGA resins. For high-Fe/Ti and high-Mg/Ti igneous samples, a three-column procedure was required, whereas a two-column procedure was used for low-Fe/Ti and low-Mg/Ti igneous samples. The Ti isotopes were analysed by MC-ICP-MS, and instrumental mass bias was corrected using a 47Ti-49Ti double-spike technique. The 47Ti-49Ti double-spike and SRM 3162a were calibrated using SRM 979-Cr, certificated value 53Cr/52Crtrue = 0.11339. Isobaric interference was evaluated by analysing Alfa-Ti doped with Na, Mg, Ca, and Mo, and results indicate that high concentrations of Na and Mg have no significant effect on Ti isotope analyses; however, Ca and Mo interferences lead to erroneous δ49/47Ti values when Ca/Ti and Mo/Ti ratios exceed 0.01 and 0.1, respectively. Titanium isotopic compositions were determined for 12 igneous reference materials, BCR-2, BHVO-2, GBW07105, AGV-1, AGV-2, W-2, GBW07123, GBW07126, GBW07127, GBW07101, JP-1, and DTS-2b. Samples yield δ49/47Ti (‰) of ?0.035 ± 0.022, ?0.038 ± 0.031, 0.031 ± 0.022, 0.059 ± 0.038, 0.044 ± 0.037, 0.000 ± 0.015, 0.154 ± 0.044, ?0.044 ± 0.018, 0.010 ± 0.022, 0.064 ± 0.043, 0.169 ± 0.034, and ?0.047 ± 0.025 (relative to OL-Ti, ±2SD), respectively; of which isotopic compositions of DTS-2b, JP-1, GBW07101, GBW07105, GBW07123, GBW07126, and GBW07127 are reported for the first time. Standard Alfa-Ti was analysed repeatedly over a ten-month period, indicating a reproducibility of ±0.047 (2SD) for δ49/47Ti, similar to the precisions obtained for geochemical reference materials.     

太平洋富稀土深海沉积物标准物质研制

深海稀土被认为是继多金属结核、富钴结壳和多金属硫化物之后发现的第四种深海矿产资源,以富含中-重稀土元素为显著特征。中国目前深海沉积物标准物质数量较少,不成系列,而且现有海洋沉积物标准物质中稀土元素总量最高为475.9μg/g,远未达到富稀土深海沉积物中的稀土元素总量(＞1000μg/g)。目前国内外尚未有富稀土深海沉积物成分分析标准物质,为满足深海稀土资源勘查需要,本文报道了国家一级标准物质太平洋富稀土深海沉积物(GBW07590)研制过程。该标准物质候选物实物样品采集自4300m东南太平洋海底,经过自然风干、粉碎、混匀和灭活加工制备后,对沉积物成分进行均匀性和稳定性检验,各成分统计结果显示样品具有良好的均匀性和稳定性。国内外11家实验室采用多种分析方法对该标准物质的62种成分进行定值,确定各项成分的标准值和不确定度,稀土总量达到2103μg/g。该标准物质的研制进一步丰富了国内外深海沉积物标准物质品类,为科学研究、深海资源开发评价和地球化学分析测试等提供科技支撑。     

NanoSr – A New Carbonate Microanalytical Reference Material for In Situ Strontium Isotope Analysis

The in situ measurement of Sr isotopes in carbonates by MC‐ICP‐MS is limited by the availability of suitable microanalytical reference materials (RMs), which match the samples of interest. Whereas several well‐characterised carbonate reference materials for Sr mass fractions > 1000 µg g^?1 are available, there is a lack of well‐characterised carbonate microanalytical RMs with lower Sr mass fractions. Here, we present a new synthetic carbonate nanopowder RM with a Sr mass fraction of ca. 500 µg g^?1 suitable for microanalytical Sr isotope research (‘NanoSr’). NanoSr was analysed by both solution‐based and in situ techniques. Element mass fractions were determined using EPMA (Ca mass fraction), as well as laser ablation and solution ICP‐MS in different laboratories. The ⁸⁷Sr/⁸⁶Sr ratio was determined by well‐established bulk methods for Sr isotope measurements and is 0.70756 ± 0.00003 (2s). The Sr isotope microhomogeneity of the material was determined by LA‐MC‐ICP‐MS, which resulted in ⁸⁷Sr/⁸⁶Sr ratios of 0.70753 ± 0.00007 (2s) and 0.70757 ± 0.00006 (2s), respectively, in agreement with the solution data within uncertainties. Thus, this new reference material is well suited to monitor and correct microanalytical Sr isotope measurements of low‐Sr, low‐REE carbonate samples. NanoSr is available from the corresponding author.     

International Association of Geoanalysts' Protocol for the Certification of Geological and Environmental Reference Materials: A Supplement

The International Association of Geoanalysts (IAG) published a protocol for the certification of reference materials in close accord with the International Organisation for Standardisation (ISO) guidelines (Kane et al. 2003). This article supplements that protocol, providing additional discussion of best approaches for pre-selecting laboratories for participation in certification projects. This discussion also makes a distinction between inter-laboratory certifications, where n = 15 is the general standard, and expert laboratory certifications, where a much smaller number of laboratories will be deemed qualified to provide data of the quality needed for certification.     

A Common Reference Material for Cadmium Isotope Studies – NIST SRM 3108

Research into natural mass‐dependent stable isotope fractionation of cadmium has rapidly expanded in the past few years. Methodologies are diverse with MC‐ICP‐MS favoured by all but one laboratory, which uses thermal ionisation mass spectrometry (TIMS). To quantify the isotope fractionation and correct for instrumental mass bias, double‐spike techniques, sample‐calibrator bracketing or element doping has been used. However, easy comparison between data sets has been hampered by the multitude of in‐house Cd solutions used as zero‐delta reference in different laboratories. The lack of a suitable isotopic reference material for Cd is detrimental for progress in the long term. We have conducted a comprehensive round‐robin assay of NIST SRM 3108 and the Cd isotope offsets to commonly used in‐house reference materials. Here, we advocate NIST SRM 3108 both as an isotope standard and the isotopic reference point for Cd and encourage its use as ‘zero‐delta’ in future studies. The purity of NIST SRM 3108 was evaluated regarding isobaric and polyatomic molecular interferences, and the levels of Zn, Pd and Sn found were not significant. The isotope ratio ¹¹⁴Cd/¹¹⁰Cd for NIST SRM 3108 lies within ～ 10 ppm Da^?1 of best estimates for the Bulk Silicate Earth and is validated for all measurement technologies currently in use.     

Mud Tank Zircon: Long‐Term Evaluation of a Reference Material for U‐Pb Dating,Hf‐Isotope Analysis and Trace Element Analysis

Zircon megacrysts from the Mud Tank carbonatite, Australia, are being used in many laboratories as a reference material for LA‐ICP‐MS U‐Pb dating and trace element measurement, and LA‐MC‐ICP‐MS determination of Hf isotopes. We summarise a database of > 10000 analyses of Mud Tank zircon (MTZ), collected from 2000 to 2018 during its use as a secondary reference material for simultaneous U‐Pb and trace element analysis, and for Hf‐isotope analysis. Trace element mass fractions are highest in dark red‐brown stones and lowest in colourless and gem‐quality ones. Individual unzoned grains can be chemically homogeneous, while significant variations in trace element mass fraction are associated with oscillatory zoning. Chondrite‐normalised trace element patterns are essentially parallel over large mass fraction ranges. A Concordia age of 731.0 ± 0.2 Ma (2s, n = 2272) is taken as the age of crystallisation. Some grains show lower concordant to mildly discordant ages, probably reflecting minor Pb loss associated with cooling and the Alice Springs Orogeny (450–300 Ma). Our weighted mean ¹⁷⁶Hf/¹⁷⁷Hf is 0.282523 ± 10 (2s, n = 9350); the uncertainties on this ratio reflect some heterogeneity, mainly between grains. A few analyses suggest that colourless grains have generally lower ¹⁷⁶Hf/¹⁷⁷Hf. MTZ is a useful secondary reference material for U‐Pb and Hf‐isotope analysis, but individual grains need to be carefully selected using CL imaging and tested for homogeneity, and ideally should be standardised by solution analysis.     

水中系列氢氧同位素标准物质的研制

我国氢氧同位素国家一级标准物质经过二十余年的使用,现已不能满足需求,急需研制代表当今分析技术水平的新的氢氧同位素国家标准物质。本文研制了系列(4个)水中氢氧同位素标准物质,其中三个采自天然水样,一个为人工配制的贫氘水,三种天然水样基本涵盖了我国境内天然水的氢氧同位素组成范围。每种标准物质随机抽取30瓶的均匀性子样,每份子样做双份分析,进行均匀性检验,四种标准物质的均匀性检验得到的F值都小于相应的自由度的临界值,显示四种标准物质的均匀性良好。标准物质的δ¹⁸O和δD值经过2年的稳定性检验,特征量值变化在不确定度范围,由此判定δD、δ¹⁸O值稳定性良好。采用国际间实验室采用不同原理的方法协同定值,11家国内外实验室分别采用Cr还原法、激光法、H₂-H₂O平衡法、高温热转换元素分析法进行水中氢同位素定值,采用CO₂-H₂O平衡法进行氧同位素定值;定值不确定度显著降低,δ¹⁸O的扩展不确定度小于0.08‰,δD的扩展不确定度小于0.9‰。该标准物质已被国家质检总局批准确为国家一级标准物质,批准号为GBW 04458~GBW 04461。     

Natural Titanite Reference Materials for In Situ U‐Pb and Sm‐Nd Isotopic Measurements by LA‐(MC)‐ICP‐MS

Titanite is a common accessory mineral that preferentially incorporates considerable amounts of U and light rare earth elements in its structure, making it a versatile mineral for in situ U‐Pb dating and Sm‐Nd isotopic measurement. Here, we present in situ U‐Pb ages and Sm‐Nd isotope measurement results for four well‐known titanite reference materials (Khan, BLR‐1, OLT1 and MKED1) and eight titanite crystals that could be considered potential reference material candidates (Ontario, YQ‐82, T3, T4, TLS‐36, NW‐IOA, Pakistan and C253), with ages ranging from ~ 20 Ma to ~ 1840 Ma. Results indicate that BLR‐1, OLT1, Ontario, MKED1 and T3 titanite have relatively homogeneous Sm‐Nd isotopes and low common Pb and thus can serve as primary reference materials for U‐Pb and Sm‐Nd microanalysis. YQ‐82 and T4 titanite can be used as secondary reference materials for in situ U‐Pb analysis because of their low common Pb. However, internal structures and mineral inclusions in YQ‐82 will require careful selection of suitable target domains. Pakistan titanite is almost concordant with an age of 21 Ma and can be used as a reference material when dating Cenozoic titanite samples.     

Molybdenum Mass Fractions and Stable Isotope Compositions of Sedimentary Carbonate and Silicate Reference Materials

A double‐spike method in combination with MC‐ICP‐MS was applied to obtain molybdenum (Mo) mass fractions and stable isotope compositions in a suite of sedimentary silicate (marine, lake, stream, estuarine, organic‐rich sediment, shales, slate, chert) and carbonate reference materials (coral, dolomite, limestones, carbonatites), and a manganese nodule reference material, poorly characterised for stable Mo isotope compositions. The Mo contents vary between 0.076 and 364 μg g^?1, with low‐Mo mass fractions (< 0.29 μg g^?1) found almost exclusively in carbonates. Intermediate Mo contents (0.73–2.70 μg g^?1) are reported for silicate sediments, with the exception of chert JCh‐1 (0.24 μg g^?1), organic‐rich shale SGR‐1b (36.6 μg g^?1) and manganese nodule NOD‐A‐1 (364 μg g^?1). The Mo isotope compositions (reported as δ⁹⁸Mo relative to NIST SRM 3134) range from ?1.77 to 1.03‰, with the intermediate precision varying between ± 0.01 and ± 0.12‰ (2s) for most materials. Low‐temperature carbonates show δ⁹⁸Mo values ranging from 0.21 to 1.03‰ whereas δ⁹⁸Mo values of ?1.77 and ?0.17‰ were obtained for carbonatites CMP‐1 and COQ‐1, respectively. Silicate materials have δ⁹⁸Mo values varying from ?1.56 to 0.73‰. The range of δ⁹⁸Mo values in reference materials may thus reflect the increasingly important relevance of Mo isotope investigations in the fields of palaeoceanography, weathering, sedimentation and provenance, as well as the magmatic realm.