Determination of Bromine and Iodine in U.S.G.S. Standard Marine Mud (MAG-1)

The concentrations of bromine and iodine in USGS reference material MAG-1 were determined by standard addition with secondary-source x-ray fluorescence spectrometric detection. Three determinations of bromine in the same sample yielded 311, 309 and 346 μg Br/g solid. The iodine content was found to be 380 μg I/g solid. The determination of bromine in a second bottle of MAG-1 (266 ± 9 μg Br/g) indicated that a large variation in halogen concentration may exist between samples of this reference material.     

Accurate Determination of Chlorine,Bromine and Iodine in U.S. Geological Survey Geochemical Reference Materials by Radiochemical Neutron Activation Analysis

Trace amounts of three halogens (chlorine, bromine and iodine) in seventeen U.S. Geological Survey (USGS) geochemical reference materials were determined by radiochemical neutron activation analysis (RNAA). The materials analysed were AGV‐2 (andesite), BCR‐2, BHVO‐2 and BIR‐1a (basalts), CLB‐1 (coal), COQ‐1 (carbonatite), DGPM‐1 (disseminated gold ore), DNC‐1a (dolerite), DTS‐2b (dunite), GSP‐2 (granodiorite), Nod‐A‐1 and Nod‐P‐1 (manganese nodules), QLO‐1a (quartz latite), SBC‐1 (marine shale), SDC‐1 (mica schist), SGR‐1b (shale rock) and W‐2a (diabase). The chlorine, bromine and iodine contents were determined to be 5.64 mg kg^?1 (BIR‐1a) to 4410 mg kg^?1 (Nod‐A‐1), 0.039 mg kg^?1 (BIR‐1a) to 52.1 mg kg^?1 (CLB‐1), and 0.041 mg kg^?1 (BIR‐1a) to 599 mg kg^?1 (CLB‐1), respectively. The RNAA data of the three halogens were compared with the corresponding data in the literature.     

DETERMINATION OF FLUORINE, CHLORINE, BROMINE AND IODINE IN SEVEN GEOCHEMICAL REFERENCE SAMPLES

The concentrations of fluorine, chlorine, bromine and iodine of seven geochemical reference samples have been determined. Analytical techniques were neutron activation analysis for chlorine, bromine and iodine and ion-selective potentiometry for fluorine. After irradiation of the samples, these halogens were separated from the matrix elements by pyrohydrolysis in presence of vanadium (V) oxide. This extraction allows to measure the four halogens in the same sample.     

Isotope Dilution MC-ICP-MS Rare Earth Element Analysis of Geochemical Reference Materials NIST SRM 610, NIST SRM 612, NIST SRM 614, BHVO-2G, BHVO-2, BCR-2G, JB-2, WS-E, W-2, AGV-1 and AGV-2

We present data for the concentrations of eleven rare earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Er, Yb, Lu) in eleven international geochemical reference materials obtained by isotope dilution multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). We have analysed both rock powders and synthetic silicate glasses, and the latter provide precise data to support the use of these as reference materials for in situ trace element determination techniques. Our data also provide precise measurements of the abundance of mono-isotopic Pr in both glasses and powders, which allows more accurate constraints on the anomalous redox-related behaviour of Ce during geochemical processes. All materials were analysed in replicate providing data that typically reproduce to better than one percent. Sm/Nd ratios in all these materials also reproduce to better than 0.2% and are accurate to < 0.2% and can thus be used as calibrants for Sm-Nd geochronology. Our analyses agree well with existing data on these reference materials. In particular, for NIST SRM 610, USGS BHVO-2, AGV-1 and AGV-2, our measured REE abundances are typically within < 2% (and mostly 1%) of REE concentrations previously determined by isotope dilution analysis and thermal ionisation mass spectrometry, consistent with the higher degree of precision and accuracy obtained from isotope dilution techniques. Close agreement of results between basaltic glass reference materials USGS BHVO-2G and BCR-2G and the BHVO-2 and BCR-2 powders from which they were created suggests that little fractionation, concentration or dilution of REE contents occurred during glass manufacture.     

DETERMINATION OF BROMINE AND IODINE IN FOUR MARINE SEDIMENT REFERENCE SAMPLES BY ENERGY-DISPERSIVE X-RAY FLUORESCENCE SPECTROMETRY

The concentrations of bromine and iodine in the USGS marine mud MAG-1, the NRCC marine sediments BCSS-1 and MESS-1, and the NBS estuarine sediment SRM 1646 have been determined by energy-dispersive x-ray fluorescence spectrometry. Matrix and intermediate thickness effects were overcome by standard additions to constant weights of each sample. 3-sigma detection limits are 6 ppm Br and 24 ppm I. There is a need for many more analysts to report their results before "usable values'can be established for these elements in marine sediment reference malterials.     

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.     

New REE and Trace Element Data on Two Kimberlitic Reference Materials by ICP-MS

Data on thirty-four minor and trace elements including all rare earth elements (REE) are reported for two kimberlitic international reference materials (SARM-39, MINTEK, RSA and MY-4, IGEM, Russia) by inductively coupled plasma-mass spectrometry (ICP-MS), some of them for the first time. Four digestion techniques (open acid, closed vessel acid, microwave and lithium metaborate fusion digestion) were used for the decomposition of samples for analysis by ICP-MS. Three other reference materials (USGS BHVO-1, CRPG BR-1 and ANRT UB-N) were analysed simultaneously using the same analytical methodology to assess the precision and accuracy of the determinations. The data obtained in this study compare well with working values wherever such values are available for comparison. Though open acid digestion was found to be very rapid, effective and convenient for the determination of several trace elements in kimberlitic samples, recoveries for heavy rare earth elements (HREE) were lower than the respective recoveries obtained by the other decomposition techniques used. The precision obtained was better than ± 6% RSD in the majority of cases with comparable accuracy. Chondrite-normalised plots of each RM for all the digestion techniques were smooth. The new data reported on the two kimberlitic reference materials make these samples useful for future geochemical studies of kimberlitic rocks.     

DETERMINATION OF THIRTY-TWO MAJOR AND TRACE ELEMENTS IN THREE NIST SOIL SRMS USING ICP-AES AND WDXRF

The National Institute for Standards and Technology (NIST) has recently released three soil standard reference materials that are uncontaminated (SRM 2709), moderately contaminated (SRM 2711), and highly contaminated (SRM 2710) with metals. The SRMs were analyzed at the U.S. Geological Survey (USGS) for thirty two major, minor and trace elements using a combination of wavelength dispersive X-ray fluorescence spectroscopy (WDXRF) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). Good agreement is observed between NIST certified values and USGS results. The wide concentration ranges for most transition metals should make these SRMs useful in assessing the accuracy of methods used in geochemical exploration and environmental studies.     

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.     

SPECTROPHOTOMETRIC DETERMINATION OF FERROUS IRON IN EIGHTEEN UNITED STATES GEOCHEMICAL REFERENCE STANDARDS

Iron (II) oxide in 50 mg samples of silicate rocks, deposits, and soils is measured after digestion with HF and HCl in the presence of ICl. The iodine produced is measured spectrophotometrically. Results are presented for the eighteen available USGS geochemical reference standards including the GXR series.     

TRACE ELEMENT DETERMINATIONS FOR USGS BASALT BHVO-1 AND NIST STANDARD REFERENCE MATERIALS 278, 688 AND 694 BY INDUCTIVELY COUPLED PLASMA-MASS SPECTROMETRY

Results are presented for 26 to 30 trace elements determined in four rock reference materials of geochemical interest: USGS Basalt BHVO-1, Rhyolite Obsidian NIST 278, Basalt NIST688, and Phosphate Rock NIST694. Determinations were made by inductively coupled plasma mass spectrometry (ICP-MS). Good agreement was obtained among solution standard comparison and standard addition analytical techniques, and among samples prepared with different dissolution methods. Generally good agreement was obtained between determined trace element values and values reported in the literature.     

Precise Determination of Ultra-Low (sub-ng g-1) Level Rare Earth Elements in Ultramafic Rocks by Quadrupole ICP-MS

We present a new method that determines precisely and accurately rare earth elements (REE) at the sub-ng g^-1 level in ultramafic rocks based on acid dissolution and quadrupole ICP-MS with systematic interference corrections on each sample. The method is demonstrated by analyses of the international geochemical reference materials, PCC-1 (peridotite), DTS-1 (dunite) and DTS-2 (dunite) provided by the United States Geological Survey (USGS), and JP-1 (peridotite) issued by the Geological Survey of Japan (GSJ). Detection limits, as rock equivalent, were calculated to be 0.01-0.08 ng g^-1 for our instrument, which is sufficiently low compared to the REE concentrations of ultramafic rocks. In addition, procedural blanks of the proposed method were 0.2-5 pg, which is negligible even for the ultra-low level REE determinations. Reproducibility obtained from separate dissolutions and measurements of USGS DTS-2 and GSJ JP-1 was 3-6%, which corresponds to the high-precision data obtained by ID-TIMS or magnetic sector field ICP-MS with a desolvating nebuliser. The REE data determined exhibit smooth chondrite-normalised REE patterns for all of the tested geochemical reference materials, and the abundances are in good agreement with recently published data.     

Chemical Characterisation of the USGS Reference Glasses GSA-1G, GSC-1G, GSD-1G, GSE-1G, BCR-2G, BHVO-2G and BIR-1G Using EPMA, ID-TIMS, ID-ICP-MS and LA-ICP-MS

The USGS reference glasses GSA-1G, GSC-1G, GSD-1G, GSE-1G, BCR-2G, BHVO-2G and BIR-1G were investigated by different analytical techniques. All these materials have a geological (basaltic) matrix and are therefore useful in igneous geochemistry as matrix-matched reference materials for microanalytical techniques. The new GS glasses have trace elements in groups at concentration levels of about < 0.01, 5, 50 and 500 μg g^-1. Their major element compositions have been determined by EPMA, and trace elements have been analysed by LA-ICP-MS and two isotope dilution techniques using TIMS and ICP-MS. EPMA and LA-ICP-MS analyses indicated that the USGS reference glasses are homogeneous at the μm to mm scale with respect to major (variations < 1-2%) and most trace elements (variations 1-4%). Trace element data obtained from the different analytical techniques agreed within an uncertainty of 1-5%, indicating that between method results are comparable. Therefore, the preliminary working values for the four USGS GS glasses calculated from these data have a low level of uncertainty.     

Homogeneity of the Geochemical Reference Material BRP-1 (Paraná Basin Basalt) and Assessment of Minimum Mass

Reference materials (RM) are required for quantitative analyses and their successful use is associated with the degree of homogeneity, and the traceability and confidence limits of the values established by characterisation. During the production of a RM, the chemical characterisation can only commence after it has been demonstrated that the material has the required level of homogeneity. Here we describe the preparation of BRP-1, a proposed geochemical reference material, and the results of the tests to evaluate its degree of homogeneity between and within bottles. BRP-1 is the first of two geochemical RM being produced by Brazilian institutions in collaboration with the United States Geological Survey (USGS) and the International Association of Geoanalysts (IAG). Two test portions of twenty bottles of BRP-1 were analysed by wavelength dispersive-XRF spectrometry and major, minor and eighteen trace elements were determined. The results show that for most of the investigated elements, the units of BRP-1 were homogeneous at conditions approximately three times more rigorous than those strived for by the test of "sufficient homogeneity". Furthermore, the within bottle homogeneity of BRP-1 was evaluated using small beam (1 mm²) synchrotron radiation XRF spectrometry and, for comparison, the USGS reference materials BCR-2 and GSP-2 were also evaluated. From our data, it has been possible to assign representative minimum masses for some major constituents (1 mg) and for some trace elements (1-13 mg), except Zr in GSP-2, for which test portions of 74 mg are recommended.     

An Inter-Laboratory Assessment of the Thorium Isotopic Composition of Synthetic and Rock Reference Materials

We present a concerted international effort to cross-calibrate five synthetic Th isotope reference materials (UCSC Th "A", OU Th "U", WUN, IRMM-35 and IRMM-36), and six rock reference materials (UCSC TML, Icelandic ATHO, USGS BCR-2, USGS W-2, USGS BHVO-2, LV18) using multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). We then compare our new values with a compilation of literature mass spectrometric data for these reference materials and derive recommended "consensus"²³⁰Th/²³²Th values for each. We also present isotope dilution U and Th concentration data for four rock reference materials (UCSC TML, Icelandic ATHO, USGS BCR-2, USGS W-2).     

Determination of Halogens (F, Cl, Br, I), Sulfur and Water in Seventeen Geological Reference Materials

Fluorine, chlorine, bromine, iodine and sulfur were determined in seventeen geological reference materials after extraction by pyrohydrolysis. Fluorine, Cl and S (as sulfate ions) were determined in the extraction solution by ion chromatography with detection limits of around 0.2 mg l⁻¹. Bromine and I were measured by ICP-MS with detection limits of 1 μg l⁻¹ for Br and 0.1 μg l⁻¹ for I. For rock samples, using normal extraction conditions (500 mg of sample and 100 ml of final solution) detection limits were 40 mg kg⁻¹ for F and Cl, 15 mg kg⁻¹ for S, 0.2 mg kg⁻¹ for Br and 0.02 mg kg⁻¹ for I. These detection limits may be improved by increasing the amount of sample and hence the concentration of the final solution. Water was also determined using an extraction technique based on H₂O degassing, reduction on zinc at 1000 °C and H₂ manometry. Our results for fluorine, chlorine, sulfur and water are in good agreement with literature data. Very few reference materials have recommended values for bromine and especially for iodine. Among the analysed samples, three are new reference materials: BHVO-2, BCR-2 and AGV-2.     

松辽盆地土壤溴的地球化学特征及其对油气的指示

Br和I是卤族元素的重要成员,I用于油气勘查取得了较好的找矿效果,但是,目前还未见到国外有关Br元素勘查油气的报道。应用松辽盆地中部8.15×104km2的多目标地球化学勘查数据,在研究土壤Br元素近地表影响因素的基础上,试验了表层土壤Br和深层土壤Br的区域地球化学异常对油气的指示意义。在松辽盆地中部发现了表层土壤Br的地球化学巨省和深层土壤Br的地球化学巨环,它们与油气富集区带、大中型油气田和火山岩油气藏相联系。土壤Br元素的表生地球化学作用和油气微渗漏是表层巨省和深层巨环形成的主要机制,因而,土壤Br元素也是战略性油气地球化学填图的一个新的辅助指标。     

Determination of REE, Y, Nb, Zr, Hf, Ta, Th and U in Geological Reference Materials LSHC-1 and Amf-1 by Solution and Laser Ablation ICP-MS

This paper presents data on REE and Y, Nb, Zr, Hf, Ta, Th and U abundances for two candidate reference materials (RMs), spinel lherzolite LSHC-1 and amphibole Amf-1, being currently developed at the Institute of Geochemistry SB RAS, Irkutsk. To determine the contents of these elements inductively coupled plasma-mass spectrometry was applied with: (i) solution nebulisation (solution ICP-MS) and (ii) laser ablation (LA-ICP-MS) of fused glass disks. The precision of results obtained by both techniques was better than 6% RSD for most elements. Accuracy was assessed by using the geochemical RMs JB-2, JGb-1 (GSJ) and MAG-1 (USGS). The trace element results by solution ICP-MS for JGb-1 and JB-2 agree with reference values presented by Imai et al. (1995, this Journal) within 1–10%. Significant differences were found for Nb and Ta determinations. The accuracy of LA-ICP-MS results evaluated by RM MAG-1 was within 4%, except for Eu (about 10%). The analytical results obtained for LSHC-1 and Amf-1 by solution ICP-MS and LA-ICP-MS were in good agreement with each other and with INAA and XRF data presented for the certification of these RMs. They can be considered as the indicative values for assigning certified values to the above-mentioned RMs.     

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 Gold in Twenty Geochemical Reference Samples by Flameless Atomic Absorption Spectrometry

After acid digestion, gold is extracted with MIBK and determinated by flameless atomic absorption spectrometry. The results for six USGS reference samples and fourteen French geochemical standards are presented and discussed. The agreement with working values for these standards is in the range of pm 5%.