Platinum-Group Element Geochemical Certified Reference Materials (GPt1-7)

Unlike the situation for other elements, few reference materials certified for the platinum-group elements are currently available. Therefore, the GPt1-7 series of PGE geochemical CRMs, prepared by the IGGE, represent an important addition and comprise a range of matrix types, including a soil, stream sediment, Mg-rich ultramafic rock, Fe-rich ultramafic rock, platinoid ore depleted in Cu, Ni and Fe, and a chromitite. The concentration of PGE in these samples ranges over 4-5 orders of magnitude and the samples were shown to have good homogeneity as assessed by a variance test. Analytical methods based on different principles were used in sample certification, including several fire assay and wet chemical procedures used for decomposition and preconcentration. Certified values for the elements Pt, Pd, Os, Ru, Ir, Rh and Au were determined by AAS, catalytic colourimetry (COL), catalytic polarography (POL), atomic emission spectrometry (AES), ICP-MS and NAA. Recently, the GPt1-7 samples were approved as national primary CRMs by the State Bureau of Technical Supervision of China.     

Determination of Gold, Silver and Platinum-Group Elements in Geochemical Reference Materials by Direct Atomic Emission Spectral Analysis Using a Multichannel Analyser Recording Device

A procedure for the analysis of geochemical samples has been developed based on direct atomic-emission spectrometry for the determination of silver, gold and the platinum-group elements. Instrumentation comprised a DC arc emission two-jet plasmatron coupled to a diffraction spectrograph and multichannel analyser for recording emission spectra. Spectrum analysis used a comprehensive library of spectral lines for practically all elements excited using this emission source. The software programme for the automatic registration of spectra and subsequent data processing are described and results presented for a number of geochemical reference materials.     

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.     

黑色页岩样品中痕量级铂族元素地球化学成分标准物质研制

介绍了黑色页岩样品中6个铂族元素铂、钯、钌、锇、铑、铱的标准物质研制过程。黑色页岩样品采自贵州黄家湾,为一次采集、一次混样的原始样品,随机抽取包装好后的样品进行检验与定值。均匀性、稳定性符合要求后,按照国际标准化组织(ISO)34、35指南的基本要求和我国一级标准物质的技术规范,采用多个实验室协同测试的定值方式,利用不同原理的分析方法对此样品的6个铂族元素进行定值。以各实验室组数据作为最小统计单元,用Grubbs准则、Dixon法检验剔除离群数据,Shapiro-Wilk法检验各元素数据分布的正态性。检验结果100%的元素呈正态或近似正态分布。定值的6个元素均符合标准值水平。     

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.     

New Progress on Certified Reference Materials for Platinum-Group Elements: IGGE GPt-8, GPt-9 and GPt-10

Three new certified reference materials (CRM), certified for the platinum-group elements (PGE), GPt-8, GPt-9 and GPt-10 were developed based on the previous CRMs IGGE GPt-1 to GPt-7. The PGE concentration of GPt-8 is about 1 ng g^-1. GPt-9 and GPt-10 are ore samples with PGE concentrations of more than 1 μg g^-1. A multi-laboratory collaborative analysis scheme was adopted in the certification procedure, in which nine highly-experienced institutes and laboratories participated. The samples were analysed for the six platinum-group elements by nickel sulfide mini fire assay, with Te coprecipitation, and were determined by ICP-MS. Osmium was determined by isotope dilution.     

地球化学与环境样品分析标准物质和GeoReM数据库

在地球化学和环境样品分析中,标准物质发挥着越来越重要的作用。尽管通常要求分析者必须提供量值溯源的测量过程的信息;但大多数论著都未给出标准物质的数据。文章强调标准物质在地球化学分析工作中的重要性,同时将地球化学与环境样品分析标准物质数据库GeoReM介绍给中国的地质分析工作者。GeoReM数据库收录了1880个地球化学和环境样品分析标准物质的定值数据、汇编数据、分析数据及其他相关信息,其中包括156个由中国制备的标准物质的数据。GeoReM数据库还给出了所收录标准物质推荐使用的首选值及其不确定度。尽管这些首选值大多都不是按照国际标准化组织的有关规定而确定的,但是它们的置信度高,因而被广泛应用于仪器校准和分析数据的质量监控。文章还指出要将中国研制的、发表在中文期刊上的标准物质也收录到GeoReM数据库中,这对于促进中国的相关研究,增加国际认可度具有重要意义。     

铂族元素地球化学标准物质的研制

ＧＰｔ＿１～７系列标准物质由土壤、水系沉积物、富镁超基性岩、富铁超基性岩、含铜镍贫铂矿石及铬铁矿等不同类型７个样品组成。铂族元素的含量范围从土壤和岩石的背景含量到矿石达４～５个数量级。经方差检验样品均匀度良好。标准物质的定值分析采用了不同类型的试金和湿化学法分离富集,以原子吸收、催化比色、催化极谱、等离子体质谱、发射光谱和中子活化等方法进行测定。定值的元素为Ｐｔ、Ｐｄ、Ｏｓ、Ｒｕ、Ｉｒ、Ｒｈ６个铂族元素及Ａｕ。该系列标准物质主要适于作铂族元素地球化学勘查和铂矿勘查中铂族元素分析的量值标准与测试的质量监控。     

Platinum-Group Element and Rhenium Concentrations in Low Abundance Reference Materials

One or two gram aliquots of twelve reference materials with low platinum-group element (PGE) abundances (Ir concentrations ranging from 30 to 510 pg g^-1) were analysed by isotope dilution ICP-MS using an on-line chromatographic matrix separation after acid digestion in a high pressure asher (HPA-S) to determine the concentrations of Ru, Pd, Re, Ir and Pt. Osmium concentrations were determined via ID-ICP-MS but as volatile OsO₄, whereas Rh concentrations were calculated by comparing the peak areas of the chromatographic peak with that of a standard solution. Validation of the method was performed and the concepts of traceability and measurement uncertainty were applied to assure comparability. The reference materials BCR-2, BHVO-1, BHVO-2, BIR-1, DNC-1, EN026 10D-3, MAG-1, RGM-1, SCo-1, SDO-1, TDB-1 and W-2 were investigated to test for their usefulness for certification. The use of TDB-1 is highly recommended because it is homogeneous at the two gram level and many values based on several different analytical procedures have been published. It is recommended that our efforts should focus on the certification of this reference material to reduce the uncertainties of its currently certified values (Pd and Pt only) and to assign certified values to the other PGE and Re. It is necessary to have at least one well-characterised RM for validation of methods applied to the analysis of PGE and Re in low abundance samples, although the matrix of TDB-1 might not completely match those of many samples.     

Determination of Iodine in Thirty Two International Geochemical Reference Materials

Thirty two geochemical reference samples have been analysed for their iodine contents by a pyrohydrolysis extraction technique, followed by colourimetry. In spite of the existence of few reported values for iodine, limiting comparison with results from this study, the four available "reference" values show good agreement with the work reported here.     

中国地质标准物质文献索引(1980—2010)

汇集了自中国开展地质标准物质研制与应用工作以来发表的中外文献和专著221条,制成按年代编排的文献索引(1980—2010)、按专题(综合性评述、研制成果发表、制备技术与方法、专题评述和专著)编排的文献索引和作者索引。最后对文献的年度分布、各专题和各类(岩石、沉积物和土壤;矿石矿物;贵金属;能源矿产;化学物相;生物、食品材料;形态、有效态;同位素和年代学;电子探针微区)标准物质的文献分布及文献的期刊分布和作者单位分布等作了简单统计。     

Reference Materials in Geoanalytical Research -Review for 2004 and 2005

This review gives an overview of the use and development of reference materials of geochemical and environmental interest in the literature of the years 2004 and 2005. In these years the performance of existing methods has been improved and new geochemical applications using new techniques have been developed. Accordingly, there was an increasing need for new reference materials, especially for in situ microanalysis and for precise stable isotope measurements. In addition, there was a notable trend for further characterisation of existing reference materials, mainly for the platinum-group elements. This review focuses on five topics: reference materials for platinum-group elements, reference glasses for in situ microanalysis, zircon reference materials, isotopic reference materials, and the development and certification of reference materials.     

Determination of Platinum-Group Elements and Forty Two Other Elements in Two Candidate Danish Cretaceous-Tertiary Boundary Clay Reference Materials by INAA, ENAA and RNAA

Ruthenium, rhodium, palladium, osmium, iridium and platinum (PGEs) and forty two other elements in two candidate geological Cretaceous-Tertiary boundary clay reference materials taken from the Fish Clay, Stevns Klint, Denmark, were determined by a combination of neutron activation analysis (NAA) consisting of instrumental, epithermal and radiochemical NAA with or without nickel sulfide fire assay preconcentration. The accuracy of the experimental values was assessed by the comparative analysis of the certified reference materials.     

Trace Element Data for Gold, Iridium and Silver in Seventy Geochemical Reference Materials

New concentrations for Au, Ir and Ag obtained by instrumental neutron activation analysis are presented for seventy geochemical reference materials. Results in agreement with literature values for Au and Ir down to concentrations of a few ng g⁻¹ were obtained. For Au and Ir concentrations above 10 ng g⁻¹, the repeatability of replicate analyses of reference materials was mostly better than 10%. For concentrations between 1 and 10 ng g⁻¹ the RSD for Ir was 10–30%, whereas for Au it was higher and more variable (20–50%). In addition, concentrations for Cd and Hg are presented for some of the same reference materials. The high RSD at relatively high concentrations seen in gold for some RMs (e.g., WMG-1, WMS-1) did not exist for Ir and suggests homogeneity for this platinum-group element at the sub-sample size used in this study. For the following eight RMs, mostly ultramafic rocks (CHR-Pt+, OREAS-13P, OREAS-14P, PCC-1, UMT-1, WMG-1, WMS-1, WPR-1), Ir measurements agreed within ± 10% of mostly certified or recommended concentrations, which ranged from 2 ng g⁻¹ to 6 μg g⁻¹. For the reference material UB-N, iridium concentration compared favourably to published results obtained by isotope dilution ICP-MS methods and a previously unrecognised heterogeneity is inferred for Au, Hg and Sb, but not for the other measured elements.     

Determination of Total Sulfur in Thirty One Geochemical Reference Materials Using an Inductively Coupled Plasma-Atomic Emission Spectrometer Fitted with a Semiconductor Photodiode Detector

The total sulfur contents of thirty one geochemical reference materials were determined using an inductively coupled plasma-atomic emission spectrometer fitted with a semiconductor photodiode detector. Most samples were decomposed using an HF-aqua regia digestion. However, a few were incompletely decomposed by simple acid digestion, and these were decomposed by a fusion method. The agreement between the analytical results from this work and published data is generally good.     

GeoReM: A New Geochemical Database for Reference Materials and Isotopic Standards

We have developed a new database named GeoReM ( http://georem.mpch-mainz.gwdg.de ) for reference materials and isotopic standards of geochemical and mineralogical interest. Reference samples include rock powders originating from the USGS, GSJ, GIT-IWG, synthetic and natural reference glasses originating from NIST, USGS, MPI-DING, as well as mineral (e.g., 91500 zircon), isotopic (e.g., La Jolla, E&A, NIST SRM 981), river water and seawater reference materials. GeoReM is a relational database, which strongly follows the concept of the three EARTHCHEM databases. It contains published analytical and compilation values (major and trace element concentrations, radiogenic and stable isotope ratios), important metadata about the analytical values, such as uncertainty, uncertainty type, method and laboratory. Sample information and references are also included. Three different ways of interrogating the database are possible: (1) sample names or material types, (2) chemical criteria and (3) bibliography. Some typical applications are described. GeoReM currently (October 2005) contains more than 750 geological reference materials, 6000 individual sets of results and references to 650 publications.     

Determination of Selenium Concentration in Sixty Five Reference Materials for Geochemical Analysis by GFAAS after Separation with Thiol Cotton

Selenium has been determined in sixty five geological reference materials of different origins by graphite furnace atomic absorption spectrometry. Samples were decomposed with a mixture of nitric and hydrofluoric acids. Selenium was reduced to Se^IV with hydrochloric acid, and then fixed and separated from the matrix on thiol cotton. After digestion of the thiol cotton in hot nitric acid, the Se concentration was measured using palladium and magnesium nitrates as a matrix modifier. The limit of determination was 0.02 μg g⁻¹, the precision of the results (relative standard deviation of 3 to 8 replicates) varied from 2.6 to 17.7% with an average of 7.9% in the range 0.02-42.7 μg g⁻¹ and was similar to the value obtained for synthetic samples. Our results are in good agreement with available literature values.     

High‐precision Determination of Gold Mass Fractions in Geological Reference Materials by Internal Standardisation

Determination of gold abundances in natural rock is critical for applications, but very challenging. Here, we report a method for determining gold with a very low mass fraction (> 0.01 ng g^?1) in rocks. The method involves Carius tube digestion with reverse aqua regia, chromatographic separation to remove most of the sample matrix and measurement by high‐sensitivity ICP‐MS. The mono‐isotopic element gold was quantified by external calibration using an internal standardisation of gold to platinum that was precisely determined by isotope dilution. The method is robust and the obtained results are indistinguishable (< 5–10%, 2s) from those independently obtained by a standard addition technique on the same solution. The results from reference materials TDB‐1 and GPt‐2 are consistent with the certified values and those determined by HF‐aqua regia digestion, confirming the validity of the method. TDB‐1 (n = 20), GPt‐2 (n = 6), BHVO‐2 (n = 9) and other mafic RMs are homogenous for gold (10–20%, 2s) at the 2 g test portion level; however, sample heterogeneity affects some RMs. Gold and platinum‐group elements also display different extents of sample heterogeneity for different RMs. Given the homogeneity observed for TDB‐1, GPt‐2 and BHOV‐2, they are recommended as well‐suited RMs for inter‐laboratory comparison studies of gold.     

Determination of Selenium in Fifty Two Geochemical Reference Materials by Hydride Generation Atomic Absorption Spectrometry

The selenium content of fifty two geochemical reference samples, issued by several reference material producers (ANRT, GIT-IWG, USGS, NIST and GSJ) has been determined by continuous hydride generation and atomic absorption spectrometry. Selenium(VI) in the digested solutions was pre-reduced to selenium(IV) by heating in 6 mol l⁻¹ HCl solution. The limit of detection was 3 ng g⁻¹ selenium in common geological samples. Some samples which contain a large amount of heavy metals were analysed by the standard addition technique. The agreement between the reported results and published data is satisfactory.