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1.
ISO Guide 35:2017 provides, for the first time, an alternative way of characterising certified reference materials using proficiency testing. In this paper, the properties of assigned values derived from the well‐established GeoPT proficiency testing scheme are examined. This scheme, designed for laboratories that undertake the routine analysis of silicate rocks and related materials, routinely has over 100 participants contributing results. Following a detailed assessment of the metrological properties of GeoPT assigned values in relation to Guide 35 recommendations, it is demonstrated that these values may be regarded as certified values, provided a number of criteria are met. These criteria include the following: a demonstration of sufficient homogeneity of the candidate CRM; circulation, when judged to be appropriate, of an established matrix‐matched CRM for co‐analysis in that round; the robust statistical analysis of data sets using GeoPT established criteria; a decision whether assigning a value is justified (including a requirement of a minimum of fifteen valid results); and an expert group to manage the certification and the maintenance of appropriate records. In summary, the GeoPT proficiency testing scheme, subject to the arrangements summarised above, is considered to be competent for the certification of geological reference materials.  相似文献   

2.
The Canadian Certified Reference Materials Project reports recommended values of lead-210 activity in four uranium reference materials previously certified for uranium and radium-226. Eleven laboratories participated in the interlaboratory program for DL-1a, BL-4a, DH-1a and BL-5; three measurement techniques were applied. Procedural and instrumental calibrations were performed with a certified lead solution from Amersham International Corp., thereby establishing traceability of the recommended values for lead-210. Activity ratios for uranium-238. radium-226 and lead-210 demonstrate these uranium reference materials to be in secular equilibrium, within experimental uncertainties.  相似文献   

3.
The Canadian Certified Reference Materials Project announces recommended values for radium-226 activity in four reference materials previously certified for uranium. Thirteen laboratories participated in the interlaboratory program for DL-la, DH-la, BL-4a and BL-5. Four measurement techniques were applied. Procedural and instrument calibrations were performed with certified radium solutions from the National Bureau of Standards, thereby establishing traceability of the recommended values for radium-226 in DL-la, DH-la, BL-4a and BL-5. These reference ores are also shown to be close to, if not in, radioactive equilibrium.  相似文献   

4.
The International Association of Geoanalysts (IAG) has certified a slate sample, OU-6, for twelve major and minor constituents, as well as thirty-five trace elements through an interlaboratory programme conducted in close compliance with the International Organization for Standardization (ISO) Guide 35 (1989). Laboratories were qualified for participation in the certification programme, based on their performance in the prior analysis of OU-6 as a proficiency test material. Thirty laboratories provided data for the certification, though not for each constituent that was certified. Certification criteria included a means of establishing traceability for the certification data, generally through concurrent analysis of the existing Geological Survey of Japan reference material JSl-1, agreement of results between laboratories and methods, and a minimum of data rejection (4% rejection rate for OU-6 data and 6% for JSl-1 data), preferably for well-understood technical reasons only. Information values are provided for an additional eight constituents where certification criteria were not met. Uncertainties developed in accordance with the "Guide on Uncertainty in Measurement" (Eurachem 2000) and representing the 95% confidence interval of the certified and information values are reported for all fifty five constituents. The material is currently available in 40 g units for distribution by the IAG. Supply is anticipated to last about ten years.  相似文献   

5.
The advent of multiple collector-inductively coupled plasma-mass spectrometry has provided an impetus to the study of isotope abundance variations in natural materials. In particular, the study of "non-traditional" stable isotopes has revealed isotope fractionation variations caused by a range of physiochemical and biological mechanisms. The magnitude of these variations may be < 1 per mil per mass unit, but are significant in terms of the experimental uncertainties involved, provided rigorous mass spectrometric protocols are followed. The double spike technique can be used effectively to evaluate isotope fractionation effects for both multiple collector-inductively coupled plasma-mass spectrometry and thermal ionisation mass spectrometry. The demanding nature of this research implies the need for internationally-accepted reference materials so that interlaboratory comparisons can be made with confidence. At present, isotopically certified reference materials are unavailable for many elements, including Cu, Zn, Mo and Cd, and it is important that this situation be rectified as soon as practicable. Until such time as isotopically certified reference materials become available for every element, stable isotope geochemists should adopt a common reference material as the standard for each element so that rigorous interlaboratory comparisons can be made.  相似文献   

6.
The continuous improvement of analytical procedures using multi‐collector technologies in ICP‐mass spectrometry has led to an increased demand for isotope standards with improved homogeneity and reduced measurement uncertainty. For magnesium, this has led to a variety of available standards with different quality levels ranging from artefact standards to isotope reference materials certified for absolute isotope ratios. This required an intercalibration of all standards and reference materials, which we present in this interlaboratory comparison study. The materials Cambridge1, DSM3, ERM‐AE143, ERM‐AE144, ERM‐AE145, IRMM‐009 and NIST SRM 980 were cross‐calibrated with expanded measurement uncertainties (95% confidence level) of less than 0.030‰ for the δ25/24Mg values and less than 0.037‰ for the δ26/24Mg values. Thus, comparability of all magnesium isotope delta (δ) measurements based on these standards and reference materials is established. Further, ERM‐AE143 anchors all magnesium δ‐scales to absolute isotope ratios and therefore establishes SI traceability, here traceability to the SI base unit mole. This applies especially to the DSM3 scale, which is proposed to be maintained. With ERM‐AE144 and ERM‐AE145, which are product and educt of a sublimation–condensation process, for the first time a set of isotope reference materials is available with a published value for the apparent triple isotope fractionation exponent θapp, the fractionation relationship ln α(25/24Mg)/ln α(26/24Mg).  相似文献   

7.
Assigned values derived from the GeoPT proficiency testing programme were compared with certified values for six certified reference materials that have been used as test materials in the GeoPT programme. Statistical analysis showed that there were few significant differences between these sets of data and that these differences had no significant impact on the GeoPT assessment when fitness‐for‐purpose criteria were taken into account.  相似文献   

8.
Traceability in Geochemical Analysis   总被引：2，自引：0，他引：2  
A review is presented of "traceability" and the way this concept can be demonstrated in the analysis of geochemical samples. It is suggested that the two practical methods are (i) by the analysis of appropriate certified reference materials with an evaluation of the agreement between analysed and certified values, and (ii) by the appropriate use of definitive, reference and standard methods of analysis. The differences between these two methods of demonstrating traceability are considered and the difficulties in applying them are discussed.  相似文献   

9.
To enable quality control of measurement procedures for determinations of Mg isotope amount ratios, expressed as δ26Mg and δ25Mg values, in Earth‐surface studies, the δ26Mg and δ25Mg values of eight reference materials (RMs) were determined by interlaboratory comparison between five laboratories and considering published data, if available. These matrix RMs, including river water SLRS‐5, spring water NIST SRM 1640a, Dead Sea brine DSW‐1, dolomites JDo‐1 and BCS‐CRM 512, limestone BCS‐CRM 513, soil NIST SRM 2709a and vegetation NIST SRM 1515, are representative of a wide range of Earth‐surface materials from low‐temperature environments. The interlaboratory variability, 2s (twice the standard deviation), of all eight RMs ranges from 0.05 to 0.17‰ in δ26Mg. Thus, it is suggested that all these materials are suitable for validation of δ26Mg and δ25Mg determinations in Earth‐surface geochemical studies.  相似文献   

10.
The NIST glass certified reference materials, SRM 610-617, have been widely adopted by the geological community as calibration samples for a variety of in situ trace element analytical techniques. There is now an urgent requirement for similar reference materials for in situ isotopic analytical techniques. We have analysed SRM 610, 612 and 614 for their Pb, Sr and Nd isotopic compositions using thermal ionisation mass spectrometry. Large differences in isotopic composition were observed between each CRM, suggesting a significant trace element content in the initial starting material (base glass). As a result, isotopic compositions for one CRM cannot be extrapolated to another, and each must be calibrated for use independently. We present the first compilation of working values for these glasses.  相似文献   

11.
随着我国对生态文明建设的重视,自然资源综合调查势在必行,对生物标准物质亦提出了新的需求。当前相关调研工作已经大面积开展,自然资源综合调查、农产品与食品安全评价都需要对生物样品元素组成进行准确测试,需要以生物标准物质作为生物成分测试量值比对和溯源的基础,因此对生物基体标准物质的需求量大幅增加。大米作为主要粮食之一,其食品安全日益受到重视,对大米中的化学成分进行准确的分析测试具有重要的现实意义,因而对大米标准物质的需求量尤为突出,但目前大米成分分析标准物质已供不应求。本文严格按照《标准物质定值的通用原则及统计学原理》（JJF 1343—2012）和《地质分析标准物质的研制》（JJF 1646—2017）等相关规范要求,开展了GBW10010a大米成分分析标准物质的复（研）制工作,包括样品采集、加工制备、均匀性检验、稳定性检验、多家实验室协作定值测试及不确定度评定等关键环节。结果表明：本次复（研）制的大米标准物质定值成分多样、量值准确可靠,符合国家一级标准物质的要求。GBW10010a共定值54项主微量元素,包括Ag、Al、As、B、Ba、Be、Bi、Ca、Cd、Ce、Co、Cr、Cs、Cu、Dy、Er、Eu、Fe、Gd、Ge、Hg、Ho、K、La、Li、Ho、Mg、Mn、Mo、N、Na、Nb、Nd、Ni、P、Pb、Pr、Rb、S、Sb、Sc、Se、Si、Sm、Sr、Tb、Th、Tl、Tm、U、V、Y、Yb、Zn,其中的39项元素给出了标准值及不确定度,包括Ag、Al、As、B、Ba、Ca、Cd、Ce、Co、Cs、Cu、Dy、Er、Fe、Hg、K、Li、Mg、Mn、Mo、N、Na、Nd、Ni、P、Pb、Pr、Rb、S、Sb、Se、Si、Sm、Sr、Tb、Tl、Y、Yb、Zn;15项元素提供参考值,包括Be、Bi、Cr、Eu、Gd、Ge、Ho、Ho、La、Nb、Sc、Th、Tm、U、V。与原有GBW10010大米标准物质相比较,GBW10010a中As、Cd、Co、Cr、Cu、Hg、Mn、Mo、Ni、Zn等重金属元素含量显著下降,其中Cd、Cu、Zn降幅较大,分别下降约39%、43%、38.7%,一定程度上反映了农田生态环境的改善。本批标准物质定值元素总数量增加了6项,新增定值元素Ag、Nb（Nb给出参考值）,并且各项元素不确定度范围整体上有所缩小,如Al、Cd、Cu、Fe、K、Mg、Mo、Na、P、Pb、Se、Zn等对生物易有影响的重要元素,表明了地质分析测试方法技术的进步及定值水平的提高。本批标准物质定值元素涵盖了具有生物效应的大部分主微量元素,适用于农业生态环境地球化学调查与评价、生物样品测试、农产品质量与食品安全评价样品测试时的分析仪器校正、分析方法评价和分析质量监控等多个领域。  相似文献   

12.
地球化学与环境样品分析标准物质和GeoReM数据库   总被引：7，自引：5，他引：2  
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。  相似文献   

13.
The original certification protocol, published by the International Association of Geoanalysts in 2003, specified that the competence of laboratories selected as competent to contribute certification measurements should be evaluated from their performance in the GeoPT proficiency testing programme. Round 39 of the IAG GeoPT proficiency testing programme provided an opportunity to examine four methods of evaluating laboratory competence based largely on the use of proficiency testing z‐scores as performance indicators. This opportunity arose because two test materials were co‐analysed by participating laboratories in this round: a syenite, SyMP‐1, supplied by the USGS, and an established CRM, the nepheline syenite, CGL 006. The performance of laboratories was assessed in four ways; in each case, consensus values and their uncertainties as derived from selective data sets of competent laboratories were compared with results derived from the routine GeoPT data assessment, involving all submitted measurements. An overall comparison of results showed no significant statistical differences in either consensus values or uncertainties between these data sets. This conclusion was unexpected and calls into question the widely held assumption that ‘better’ consensus data would be obtained from a subset of laboratories judged to be competent on the basis of proficiency testing performance indicators.  相似文献   

14.
The Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences recently prepared four certified reference materials for hydrogen and oxygen stable isotopes in water, which are called ‘China Standard Water' (CSW)‐HO1–HO4 (hereafter referred to as HO1–HO4). These reference materials are intended for calibration purposes and provide reference values of their relative difference in 2H/1H and 18O/16O isotope‐amount ratios expressed in delta notation, normalised to the VSMOW–SLAP scale. The certified values of the reference materials were determined by an interlaboratory comparison of results from eleven participating laboratories. This paper describes in detail the production and certification procedure of the four reference materials. The first analytical data for the reference materials are also provided using a variety of analytical techniques, namely CO2–H2O equilibration and laser spectroscopy for δ18O and Cr reduction, as well as H2–H2O equilibration, laser spectroscopy, and high‐temperature conversion for δ2H. The reference values for materials HO1–HO4 and their associated uncertainties are assigned.  相似文献   

15.
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.  相似文献   

16.
A voltammetric method for the determination of the high field‐strength elements Ti, Zr, Hf, Nb and Ta by adsorptive stripping of their tartrate complexes is presented. The applicability of the method to geological and metallurgical samples is illustrated by the analysis of certified reference materials (USGS BCR‐2 basalt, BCS‐CRM 388 zircon and Euronorm CRM 579‐1 ferroniobium). Suitable sample preparation techniques, involving fusion with LiBO2 and acidic and basic fluxes, followed by preliminary separation by anion chromatography are described. The method is rapid, affordable and environmentally friendly as it does not require problematic compounds such as hydrofluoric acid or toxic solvents and represents an alternative to more commonly used methods (AAS, ICP‐OES, ICP‐MS).  相似文献   

17.
Due to matrix interference and sample particle size effects, some of the most important and difficult issues in laser‐induced breakdown spectroscopy (LIBS) analysis are the calibration and quantitative measurement of a complex matrix. This study proposes the use of borate fusion as an alternative sample preparation procedure for the quantitative measurement of Al, Fe, Si and Ti in bauxite by LIBS. Analytical calibration curves were made using bauxite certified reference materials (CRM), and the precision and accuracy of the methods were evaluated by analysing an additional bauxite CRM, using two different approaches: pressed powder pellets and fused glass beads. The borate fusion method was the most suitable sample preparation technique, since particle size effects and matrix interference could be minimised, obtaining better linearity on the analytical calibration curves (r2), and more accurate and more precise results for bauxite analysis.  相似文献   

18.
Reference materials (RM) are essential to achieve traceability of measurements. Specific uses of RM in analytical laboratories are the validation of methods, the calibration of instruments, the quality control and the demonstration of proficiency. This paper describes the certification of a new geochemical reference material, named BRP-1 (Basalt Ribeirão Preto), and acts as the certificate of analysis for this RM. The rock sample was crushed and pulverised at the USGS (Denver, USA), homogenised and split into 1920 bottles, with 55 g each. BRP-1 was transported back to Brazil and the homogeneity between and within bottles was assessed to demonstrate sufficient homogeneity for certification. The chemical characterisation was performed by twenty-five laboratories. Each laboratory received two bottles of BRP-1 and one of BCR-2 (Basalt Columbia River) used for quality control (QC). Reference values and uncertainties were calculated for forty-four constituents of BRP-1, following ISO Guide 35 recommendations and the IAG Protocol. The calculation of each reference value included data of proven traceability from at least ten laboratories using two or more analytical techniques and the uncertainties combines the characterisation and between bottle homogeneity contributions.  相似文献   

19.
The preparation and characterisation of certified reference materials of four selenium‐rich rocks (GBW07397 to GBW07400) are described in this paper. The raw materials were derived from selenium‐rich rocks in two famous seleniferous regions, Enshi Prefecture, Hubei Province and Ziyang County, Shaanxi Province, China. Sample homogeneity and stability were tested by inductively coupled plasma‐mass spectrometry and atomic fluorescence spectrometry. The determined element mass fractions included selenium, arsenic, copper, zinc, molybdenum, cadmium, lead, vanadium and silver. Except for silver, the results of analysis of variance (ANOVA) and the relative standard deviations of the element mass fractions showed that the four materials exhibited good homogeneity and stability. Ten laboratories were involved in an interlaboratory comparison scheme for certification. Eight element mass fractions in the selenium‐rich rocks were assigned as certified values, while only indicative values were obtained for Ag mass fractions. The certified values and expanded uncertainties for the selenium mass fractions in GBW07397–GBW07400 are 0.96 ± 0.05, 1.03 ± 0.05, 49 ± 4 and 38.5 ± 1.9 μg g?1, respectively.  相似文献   

20.
We have determined 238U/235U ratios for a suite of commonly used natural (CRM 112a, SRM 950a, and HU-1) and synthetic (IRMM 184 and CRM U500) uranium reference materials by thermal ionisation mass-spectrometry (TIMS) using the IRMM 3636 233U-236U double spike to accurately correct for mass fractionation. Total uncertainty on the 238U/235U determinations is estimated to be <0.02% (2σ). These natural 238U/235U values are different from the widely used ‘consensus’ value (137.88), with each standard having lower 238U/235U values by up to 0.08%. The 238U/235U ratio determined for CRM U500 and IRMM 184 are within error of their certified values; however, the total uncertainty for CRM U500 is substantially reduced (from 0.1% to 0.02%). These reference materials are commonly used to assess mass-spectrometer performance and accuracy, calibrate isotope tracers employed in U, U-Th and U-Pb isotopic studies, and as a reference for terrestrial and meteoritic 238U/235U variations. These new 238U/235U values will thus provide greater accuracy and reduced uncertainty for a wide variety of isotopic determinations.  相似文献   

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