Determination of Chlorine in Nine Rock Reference Materials by Isotope Dilution Mass Spectrometry

A procedure for the determination of chlorine by the isotope dilution technique (ID) using negative thermal ionisation mass spectrometry (N-TIMS) is described. Silicate samples of about 10 mg were spiked and decomposed with hydrofluoric acid, and chlorine was isolated by precipitation of silver chloride after neutralisation with Ca(OH)₂. The ammonical solution of AgCl was then subjected to N-TIMS. Replicate analyses of rock reference materials, typically of JB-1 and JR-1, demonstrated the high quality of the analyses (precision for Cl was ± 1-2%). We present here the most precise data sets of chlorine concentrations in nine igneous rock reference materials, three basalts (JB-1, JB-2, JB-3), two andesites (JA-3, AGV-1), two rhyolites (JR-1, JR-2) and two granodiorites (JG-3, GSP-1). The chlorine concentrations found ranged from 152 μg g-1 in AGV-1 to 1008 μg g^-1 in JR-1. Our results presented here are partly (but not completely) in agreement with recommended values, where they are available. The N-TIMS ID technique can thus be used as a means of determining low chlorine contents in silicate materials to high precision.     

Determination of Lithium Contents in Silicates by Isotope Dilution ICP-MS and its Evaluation by Isotope Dilution Thermal Ionisation Mass Spectrometry

A precise and simple method for the determination of lithium concentrations in small amounts of silicate sample was developed by applying isotope dilution-inductively coupled plasma-mass spectrometry (ID-ICP-MS). Samples plus a Li spike were digested with HF-HClO₄, dried and diluted with HNO₃, and measured by ICP-MS. No matrix effects were observed for ⁷Li/⁶Li in rock solutions with a dilution factor (DF) of 97 at an ICP power of 1.7 kW. By this method, the determination of 0.5 μg g^-1 Li in a silicate sample of 1 mg can be made with a blank correction of < 1%. Lithium contents of ultrabasic to acidic silicate reference materials (JP-1, JB-2, JB-3, JA-1, JA-2, JA-3, JR-1 and JR-2 from the Geological Survey of Japan, and PCC-1 from the US Geological Survey) and chondrites (three different Allende and one Murchison sample) of 8 to 81 mg were determined. The relative standard deviation (RSD) was typically < 1.7%. Lithium contents of these samples were further determined by isotope dilution-thermal ionisation mass spectrometry (ID-TIMS). The relative differences between ID-ICP-MS and ID-TIMS were typically < 2%, indicating the high accuracy of ID-ICP-MS developed in this study.     

Multi-Element Isotope Dilution Sector Field ICP-MS: A Precise Technique for the Analysis of Geological Materials and its Application to Geological Reference Materials

We present a multi-element technique for the simultaneous determination of twelve trace elements in geological materials by combined isotope dilution (ID) sector field inductively coupled plasma-mass spectrometry (SF-ICP-MS) following simple sample digestion. In addition, the concentrations of fourteen other trace elements have been obtained using the ID determined elements as internal standards. This method combines the advantages of ID (high precision and accuracy) with those of SF-ICP-MS (multi-element capability, fast sample processing without element separation) and overcomes the most prevailing drawbacks of ICP-MS (matrix effects and drift in sensitivity). Trace element concentration data for BHVO-1 (n = 5) reproduced to within 1–3% RSD with an accuracy of 1–2% relative to respective literature values for ID values and 2–3% for all other values. We have applied this technique to the analysis of seventeen geological reference materials from the USGS, GSJ and IAG. The sample set also included the new USGS reference glasses BCR-2G, BHVO-2G and BIR-1G, as well as the MPI-DING reference glasses KL2-G and ML3B-G, and NIST SRM 612. Most data agreed within 3–4% with respective literature data. The concentration data for the USGS reference glasses agreed in most cases with respective data of the original rock powder within the combined standard uncertainty of the method (2–3%), except the U concentration of BIR-1G, which showed a three times higher concentration compared to BIR-1.     

Determination of Bromine and Iodine in Twenty-three Geochemical Reference Materials by ICP-MS

Trace amounts (from nanogram to microgram levels) of bromine and iodine were determined by inductively coupled plasma-mass spectrometry (ICP-MS) in twenty-three geochemical reference materials issued by the GSJ, USGS, IAEA etc. The pyrohydrolysis technique was used to separate bromine and iodine from samples analysed in the form of powder. The accuracy and precision of the experimental values were assessed by the comparative analysis of well established reference materials such as USGS AGV-1, BCR-1 and IGGE GBW07312. The measured values agreed well with reported values within a 10% error range. We also report reliable new data for these elements in these geochemical reference materials.     

Molybdenum Concentrations Measured in Eleven USGS Geochemical Reference Materials by Isotope Dilution Thermal Ionisation Mass Spectrometry

Molybdenum concentrations in eleven USGS geochemical reference materials AGV-1, BCR-1, BHVO-1, BIR-1, DNC-1, DTS-1, G-2, GSP-1, MAG-1, PCC-1 and W-2 were measured by isotope dilution thermal ionisation mass spectrometry (ID-TIMS). In every case but one, the concentrations determined in this study were significantly lower than the current consensus values. Molybdenum concentrations determined by ID-TIMS are inherently more accurate and precisions may be up to an order of magnitude higher than those measured by other analytical techniques.     

同位素稀释等离子体质谱法测定岩石中的铂

报道了以普通铂标准溶液标定198Pt稀释剂溶液的浓度,采用同位素稀释等离子体质谱法测定岩石中的Pt。稀释剂标定结果得到该198Pt稀释剂溶液的浓度为19.76μg/g(n=4,RSD=0.16%)。4次测定标准物质GBW07293(取样量约0.5g,推荐浓度440±37ng/g)中Pt含量,结果分别为412.0±2.6ng/g、495.9±2.7ng/g、519.6±3.5ng/g和677.3±3.8ng/g。单份试样重复测量的相对标准偏差<1%。由于铂族元素的块金效应,各份平行测定的结果较分散。     

Determination of In and Sn Mass Fractions in Sixteen Geological Reference Materials by Isotope Dilution MC‐ICP‐MS

Mass fractions of Sn and In were determined in sixteen geological reference materials including basaltic/mafic (BCR‐2, BE‐N, BHVO‐1, BHVO‐2, BIR‐1, OKUM, W‐2, WS‐E), ultramafic (DTS‐2b, MUH‐1, PCC‐1, UB‐N) and felsic/sedimentary reference materials (AGV‐2, JA‐1, SdAR‐M2, SdAR‐H1). Extensive digestion and ion exchange separation tests were carried out in order to provide high yields (> 90% for Sn, > 85% for In), low total procedural blanks (~ 1 ng for Sn, < 3 pg for In) and low analytical uncertainties for the elements of interest in a variety of silicate sample matrices. Replicate analyses (n = 2–13) of Sn–In mass fractions gave combined measurement uncertainties (2u) that were generally < 3% and in agreement with literature data, where available. We present the first high‐precision In data for reference materials OKUM (32.1 ± 1.5 ng g^?1), DTS‐2b (2.03 ± 0.25 ng g^?1), MUH‐1 (6.44 ± 0.30 ng g^?1) and PCC‐1 (3.55 ± 0.35 ng g^?1) as well as the first Sn data for MUH‐1 (0.057 ± 0.010 μg g^?1) and DTS‐2b (0.623 ± 0.018 μg g^?1).     

硅酸盐氧同位素标样研制

本文介绍了硅酸盐氧同位素标准物质(SH和H)的研制。均匀性检验证实该标准物质是均匀的。该标准物质采用直接比较测量法标定,即直接与国际标准V-SMOW和SLAP进行比较。 国际标准水样采用CO_2-H_2O平衡法制备CO_2;石英标样采用BrF_5法制备CO_2。将六个定值实验室提供的数据统一处理后,获得SH和H的δ~(18)Ox/v-s_(MOW)值分别为11.11±0.06(‰)和-1.75+0.08(‰)。该标准物质于89年12月被国家技术监督局批准为国家一级标准物质,山阳石英标样(SH)统一编号为G     

Iodine (and Other Halogens) in Twenty Six Geological Reference Materials by ICP-MS and Ion Chromatography

Analytical results for iodine in twenty six geological reference materials (RM) are presented. Bromine, fluorine and chlorine were also determined in some samples. Pyrohydrolysis in a heated quartz tube under a wet oxygen flow was used for the separation of the halogens from the matrix and the evolved gas was absorbed in a trap solution. The halogens were measured by ICP-MS and ion chromatography (IC). All four halogens can be collected in the trap solution from one combustion procedure. The analysed samples range in type from igneous rocks to terrestrial and marine sediments. Precision, detection limits, and accuracy are also presented.     

Determination of Trace Elements in Twenty Six Chinese Geochemistry Reference Materials by Inductively Coupled Plasma-Mass Spectrometry

We report new data for thirty seven elements determined in twenty six Chinese geochemistry reference materials using inductively coupled plasma-mass spectrometry and a reliable and simple dissolution technique. One hundred milligrams of sample were digested with 1 ml of HF and 0.5 ml of HNO₃ in PTFE-lined stainless steel bombs heated to 200 °C for 12 hours. Insoluble residues were dissolved using 6 ml of 40% v/v HNO₃ heated to 140 C for 3 hours. Analytical calibration was accomplished using aqueous standard solutions. Rhodium was used as an internal standard to correct for matrix effects and instrument drift. Precisions were typically better than 5% RSD. Most of the data presented here agree well with the published certified values. For the elements Zr, Hf and most other trace elements, the measured values were less than 10% in error when compared to certified values.     

Determination of the Platinum-Group Elements and Gold in Twenty Rock Reference Materials by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) after Pre-Concentration by Nickel Sulfide Fire Assay

The platinum-group elements (PGE) and gold have been determined in twenty international rock reference materials by inductively coupled plasma-mass spectrometry (ICP-MS) after pre-concentration by a nickel sulfide fire assay. It was possible to achieve determination limits for a 50 g sample that ranged from 1 pg g^-1 (Rh) to 23 pg g^-1 (Au). Compared to published certified and recommended values for rock reference materials, the trueness of the method was found to be good. However, in some cases we observed large deviations for all elements in the sub 10 ng g^-1 range within individual reference sample splits. Our results show that the PGE and Au are inhomogeneously distributed in the reference materials analysed here, where they are present in low concentrations, using 50 g test portions.     

Determination of Chromium, Nickel, Copper and Zinc in Milligram Samples of Geological Materials Using Isotope Dilution High Resolution Inductively Coupled Plasma-Mass Spectrometry

A simple and accurate method for the determination of Cr, Ni, Cu and Zn at μg g^?1 levels in milligram‐sized bulk silicate materials is reported using isotope dilution high‐resolution inductively coupled plasma‐mass spectrometry (HR‐ICP‐MS) with a flow injection system. Silicate samples with Cr, Ni, Cu and Zn spikes were digested with HF‐HBr and Br₂, and subsequently decomposed at 518 K in a Teflon bomb. In this procedure, all sulfides and chromite, major hosts of these elements, were completely decomposed, thus allowing for isotope equilibration between the sample and spike. Magnesium and Al fluorides formed after the digestion of the sample were removed by centrifugation, and the supernatant was directly aspirated into a HR‐ICP‐MS at a mass resolution of 7500, where interfering oxide ions, ArO⁺, CaO⁺, TiO⁺, CrO⁺ and VO⁺, were separated from Cr⁺, Ni⁺, Cu⁺ and Zn⁺. No matrix effects were observed down to a dilution factor of 50. Detection limits for these elements in silicate samples were < 0.04 μg g^?1. The effectiveness of the technique was demonstrated by the analysis of 13 to 40 mg test portions of USGS and GSJ silicate reference materials with a major element composition ranging from andesite to peridotite, in addition to 8‐23 mg of the Smithsonian reference Allende. Both the reproducibility and the deviation from the reference value for most reference materials of various rock types were < 9%, and thus confirm that the method gives accurate analytical results for small sample sizes over a wide range of Cr, Ni, Cu and Zn contents. This method is, therefore, suitable for analysing small and/or precious bulk samples, such as meteorites, mantle peridotites and mineral separates, and for the characterisation of silicate and sulfide minerals for use as calibration samples in secondary ion mass spectrometry or laser ablation ICP‐MS.     

Comparison of UV and IR Laser Ablation ICP-MS on Silicate Reference Materials and Implementation of Normalisation Factors for Quantitative Measurements

Direct analysis of geological reference materials was performed by LA-ICP-MS using two Nd:YAG laser systems operating at 266 nm and 1064 nm. The aim of this work was to compare UV and IR laser ablation and to assess the potential of the technique for the quantitative bulk analysis of rocks, sediments and soils. The laser sampling process was investigated and the analytical performance of both systems was compared. The influence of the laser operating conditions and the nature of the matrix on ICP-MS response factors calculated for major, minor and trace elements was evaluated. Under consistent laser settings, the response factors appeared to be matrix dependent. For a given matrix, the response factors were also significantly different for the two lasers. Normalisation with a single matrix element was effective only for matrices with similar mineralogy. When operating at 266 nm instead of 1064 nm, matrix effects could be reduced but not overcome. However, variations of the response factors between the different matrices appeared to be similar within distinct groups of elements, reflecting geochemical associations. When using multiple internal standards, matrix effects but also effects of the laser wavelength, could be fully compensated.     

Assessment of Dissolution of Silicate Rock Reference Materials with Ammonium Bifluoride and Nitric Acid in a Microwave Oven

The complete dissolution of representative test portions of powdered rock samples for the determination of the mass fractions of trace elements by ICP‐MS relies either on aggressive and time‐consuming acid digestions or fusion/sintering with appropriate fluxes. Here, we evaluate a microwave oven dissolution method that employs a solution of NH₄HF₂ and HNO₃. The entire procedure occurs in a closed vessel system and takes up to 4 h. In hundreds of digestions, the precipitation of fluorides was never observed. Replicate decomposition of 100 mg of twenty‐one international reference materials (RMs) of igneous rocks, and also one of a shale presented mostly satisfactory recoveries of forty‐one trace elements. Important exceptions were Zr and Hf in G‐2 and GSP‐2 (mean recoveries of ca. 70%), although for four other felsic rock RMs, the digestion was complete. For ultramafic rock RMs, we present Cr results that indicate quantitative dissolution of Cr‐bearing phases. We discuss the findings and conclude that advances in sample preparation of geological materials for instrumental analysis would benefit from a better understanding of how specific characteristics, such as composition and crystallinity of certain minerals, may affect their reactivity.     

Determination of Rare Earth Elements in Geological Reference Materials: A Comparative Study by INAA and ICP-MS

Data was obtained for the rare earth elements (REE) by instrumental neutron activation analysis (INAA) and inductively coupled plasma-mass spectrometry (ICP-MS) in twenty geological reference materials. In general, the precision obtained by ICP-MS is better for the light REE, decreasing with increasing atomic number. This is partly a result of the occurrence of the heavy REE at low concentrations. The precision of the data obtained by INAA is good (5% RSD). The data obtained also showed that for the elements determined by both methods, the accuracy is similar for the light REE and better for the middle and heavy REEs by INAA. Higher uncertainty is achieved by ICP-MS mainly for elements at very low concentrations, occurring at about ten times the chondritic values.     

Accurate and Precise Elemental Abundance of Zinc in Reference Materials by an Isotope Dilution Mass Spectrometry TIMS Technique

A thermal ionisation mass spectrometric technique enabled the abundance of Zn in geological and biological reference materials and water samples to be measured by double spiking isotope dilution mass spectrometry enriched in the ⁶⁷Zn and ⁷⁰Zn isotopes. In the past, thermal ionisation mass spectrometry proved to be difficult for low-level zinc isotopic measurements. The size of Zn samples used for isotopic determination, in particular the biological RMs, represents an important breakthrough. These results represent the most accurate and precise concentrations measured for Zn in these samples. The maximum fractional uncertainty was that for TILL-3 (2%), while the minimum fractional uncertainty was 0.7% for both BCR-1 and W-2. The inhomogeneity of Zn in HISS-1 was revealed while other reference materials appeared homogeneous at the 95% confidence uncertainty. The certified concentration of Zn in HISS-1 and IMEP-19 by their producers are 28% and 3.8% higher than the values measured in this work. These are the first Zn concentration measurements in these materials by the isotope dilution-TIMS technique, except for BCR-1, NIES N^o 9 and IMEP-19. Reducing the blank enabled accurate measurement in water at the ng g^-1 level demonstrating the applicability of the technique for low-level Zn samples.     

Boron Isotopic Composition and Concentration of Ten Geological Reference Materials

We present boron isotope and concentration data from magmatic (komatiitic to rhyolitic) and sedimentary geological silicate and artificial glass reference materials that cover a wide spectrum of boron isotope compositions and boron concentrations. Boron isotope compositions were determined by TIMS (Cs₂BO₂⁺ -graphite and BO₂^- method) and boron concentrations by ICP-AES. Boron concentrations ranged from 7 to 159μ g^-1 and agree within 14% with published values. Based on replicate analyses of individually prepared sample aliquots an overall external reproducibility of better than 10% was determined. The obtained δ¹¹B values ranged from -12.6 to +13.6% and were reproducible within 1.1 % (2 RSD; excluding NTIMS) on the basis of individually prepared sample aliquots. The δ¹¹B values of JA-1 (+5.3%), JB-3 (+5.9%) and JR-2 (+2.9%) overlap the published data within analytical uncertainty. For the first time δ¹¹B values for the TB (-12.6%) and the MPI-DING glasses GOR-128-G (+13.6%), GOR-132-G (+7.1 %) and StHs6/80-G (-4.5%) are reported. The δ¹¹B values obtained by the Cs₂BO₂⁺ -graphite and the BO₂^- method as well as the majority of δ¹¹B values obtained using different sample preparation methods agree within analytical uncertainty. Therefore, we conclude that none of these analytical methods introduce any systematic error on the obtained δ¹¹B values.     

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.     

Determination of Ge, As, Se and Te in Silicate Samples Using Isotope Dilution-Internal Standardisation Octopole Reaction Cell ICP-QMS by Normal Sample Nebulisation

A method for the determination of Ge, As, Se and Te in silicate samples using isotope dilution-internal standardisation (ID-IS) octopole reaction cell (ORC) ICP-QMS by normal sample nebulisation was developed. The method does not involve either hydride generation or ion exchange. Germanium, Se and Te were determined by isotope dilution (ID), and As was determined by ID-IS. A silicate sample with an added Ge-Se-Te spike was digested with an HF-HNO₃-HBr mixture, dried, re-dissolved with HF and the supernatant liquid was directly aspirated into an ORC-ICP-QMS instrument with He or H₂ gas. No matrix effects were observed down to a dilution factor (DF) of ∼ 70 for Ge, Se and Te and DF of ∼ 1000 for As, which resulted in 3s detection limits in silicates of 2, 1, 0.1 and 4 ng g⁻¹, respectively. Advantages of the method are the simple sample introduction as well as a capability of determining S, Ti, Zr, Nb, Mo, Sn, Sb, Hf and Ta by ID-IS-ICP-QMS/SFMS from the same solution. Furthermore, the total sample solution consumption was only 0.253 ml with DF = 2000. Therefore, only a 0.13 mg test portion was required. To demonstrate the applicability of this technique, Ge, As, Se and Te in eight silicate reference materials were determined, as well as S, Ti, Zr, Nb, Mo, Sn, Sb, Hf and Ta in four carbonaceous chondrites.     

Determination of Selenium and Tellurium in Basalt Rock Reference Materials by Isotope Dilution Hydride Generation-Inductively Coupled Plasma-Mass Spectrometry (ID-HG-ICP-MS)

Promising methods have been developed recently for the determination of selenium (Se) and tellurium (Te) in geological materials at ng g⁻¹ and lower levels, using hydride generation-inductively coupled plasma-mass spectrometry. Here we report on a new isotope dilution-hydride generation-inductively coupled plasma-mass spectrometry (ID-HG-ICP-MS) method for the simultaneous determination of Se and Te, which is applied to basalts, and modified compared to previous work. The basalts were attacked and dissolved with hydrofluoric and nitric acid, spiked with enriched isotopes, and passed through a cation exchange column (AG 50-X8 100–200 mesh) to separate the major cations that interfere with Se and Te detection (e.g., Fe). The detection limits of this method were 0.010 ng g⁻¹ for Se and 0.0030 ng g⁻¹ for Te, well below the concentrations of Se and Te expected in basalts. The precision of the method for Se was 12.2 to 15.1% and for Te was 4.6 to 7.2% RSD from replicate analyses of basalt reference samples. The accuracy for Se determinations was 61 to 94% and for Te 28 to 100% of values previously reported in the literature for selected USGS reference materials.