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1.
We report homogeneity tests on large natural apatite crystals to evaluate their potential as U reference materials for apatite fission‐track (AFT) thermochronology by laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS). The homogeneity tests include the measurements of major element concentrations by electron probe microanalysis (EPMA), whereas for U concentration, isotope dilution (ID) ICP‐MS and laser ablation (LA) ICP‐MS were employed. Two apatite crystals are potential reference materials for LA‐ICP‐MS analysis: a 1 cm3 fraction of a Durango crystal (7.5 μg g?1 U) and a 1 cm3 Mud Tank crystal (6.9 μg g?1 U). The relative standard deviation (1 RSD) of the U concentration determined by ID‐ICP‐MS of both apatite crystals was ≤ 1.5%, whereas 1 RSD for the LA‐ICP‐MS results was better than 4%, providing sufficient homogeneity for fission‐track dating. The results on the U homogeneity for two different apatite samples are an important step towards establishing in situ dating routines for AFT analysis by LA‐ICP‐MS.  相似文献   

2.
Iron formations (IFs) typically contain low mass fractions of most trace elements, including the rare earth elements (REE), and few publications describe analytical methods dedicated to this matrix. In this study, we used bomb and table‐top acid dissolution procedures and ICP‐MS to determine the mass fractions of trace elements in IF reference materials FER‐1, FER‐2, FER‐3, FER‐4 and IF‐G. The full digestion of the IF samples with the bomb procedure required the addition of a small amount of water together with the acids. The results obtained by this method mostly agreed statistically with published values. The most remarkable exception was the higher values obtained for the heavy REE in FER‐3. The recoveries of the REE obtained with the table‐top procedure were slightly higher than those of the bomb digestion, except for the values of the heavy REE in FER‐3 and FER‐4, which were up to 30% lower than published values. Sintering of the samples with sodium peroxide was performed to determine the REE, but the results tended to be lower than those derived following acid digestion. On the whole, the recoveries showed dependence on the conditions of digestion, but subtle differences in trace mineral composition between samples also exerted influence on the analytical results for trace elements.  相似文献   

3.
The natural river water certified reference material SLRS‐5 (NRC‐CNRC) was routinely analysed in this study for major and trace elements by ten French laboratories. Most of the measurements were made using ICP‐MS. Because no certified values are assigned by NRC‐CNRC for silicon and 35 trace element concentrations (rare earth elements, Ag, B, Bi, Cs, Ga, Ge, Li, Nb, P, Rb, Rh, Re, S, Sc, Sn, Th, Ti, Tl, W, Y and Zr), or for isotopic ratios, we provide a compilation of the concentrations and related uncertainties obtained by the participating laboratories. Strontium isotopic ratios are also given.  相似文献   

4.
A HF‐free sample preparation method was used to purify silicon in twelve geological RMs. Silicon isotope compositions were determined using a Neptune instrument multi‐collector‐ICP‐MS in high‐resolution mode, which allowed separation of the silicon isotope plateaus from their interferences. A 1 μg g‐1 Mg spike was added to each sample and standard solution for online mass bias drift correction. δ30Si and δ29Si values are expressed in per mil (‰), relative to the NIST SRM 8546 (NBS‐28) international isotopic RM. The total variation of δ30Si in the geological reference samples analysed in this study ranged from ‐0.13‰ to ‐0.29‰. Comparison with δ29Si values shows that these isotopic fractionations were mass dependent. IRMM‐17 yielded a δ30Si value of ‐1.41 ± 0.07‰ (2s, n = 12) in agreement with previous data. The long‐term reproducibility for natural samples obtained on BHVO‐2 yielded δ30Si = ‐0.27 ± 0.08‰ (2s, n = 42) on a 12 month time scale. An in‐house Si reference sample was produced to check for the long‐term reproducibility of a mono‐elemental sample solution; this yielded a comparable uncertainty of ± 0.07‰ (2s, n = 24) over 5 months.  相似文献   

5.
A method was developed for the determination of low‐level rare earth elements (REEs) and thorium in ultramafic samples by inductively coupled plasma‐mass spectrometry. The conventional method for the digestion of ultramafic rocks using HNO3 and HF results in considerable amounts of insoluble fluorides because of the high contents of Mg (generally up to 24% m/m) in these rocks. In this study, we used H3BO3 as a complexing agent to break down the insoluble fluorides, and then separated the REEs from Fe and Mg major and Ba, Ca, Cr minor matrices by anion exchange and co‐precipitation, respectively. The whole procedural blanks estimated from sample‐free analyses ranged from 0.232 ng for Ce to 0.006 ng for Tm and Lu. Limits of detection for this method, defined as three times the standard deviation of these blank analyses, varied from 0.51 ng g?1 for Ce to 0.03 ng g?1 for Lu. The recovery of REEs using this technique, as determined using the standard addition method, ranged from 92.9% for Y to 102.0% for Er with 3% (RSD) variation. The method was validated using GAS (GeoPT‐12), JP‐1 and PCC‐1, and the results were comparable to literature values, elucidating the applicability to the determination of ultra trace REEs in ultramafic rocks.  相似文献   

6.
This study reports a robust procedure that permits precise measurement of all fourteen naturally occurring rare earth element (REE) concentrations, present at ng kg?1 to sub ng kg?1 levels, in ~ 100 ml seawater. This procedure is simple and can be routinely applied to measure seawater REEs with relatively high sample throughput. The procedure involves addition of a 142Ce‐145Nd‐171Yb‐enriched spike mixture, iron co‐precipitation, REE purification with chromatographic separation and the use of a magnetic‐sector‐field ICP‐MS (Element 2) coupled with a desolvating sample introduction system (Aridus 1). Critical steps of the procedure, including co‐precipitation pH and matrix removal, have been optimised through a set of experiments described here. The accuracy of the new procedure was assessed against a gravimetric mixture of REEs, and the precision was demonstrated by repeated measurement of two well‐mixed natural seawaters. Repeated analyses of these seawater reference materials (RMs), using ~ 100 ml seawater for each aliquot, indicate precision of 3% (1s) for the REEs. Measured REE concentrations of two uncertified seawater RMs (CASS‐4 and NASS‐5) are consistent with published values, and REE concentrations of the GEOTRACES intercalibration samples show good agreement with those reported by other participant laboratories. REE concentrations for other intercalibration samples (SAFe and Arctic PS70) are also reported.  相似文献   

7.
An in situ, medium‐resolution LA‐ICP‐MS method was developed to measure the abundances of the first‐row transition metals, Ga and Ge in a suite of geological materials, namely the MPI‐DING reference glasses. The analytical protocol established here hinged on maximising the ablation rate of the ultraviolet (UV) laser system and the sensitivity of the ICP‐MS, as well minimising the production of diatomic oxides and argides, which serve as the dominant sources of isobaric interferences. Non‐spectral matrix effects were accounted for by using multiple external calibrators, including NIST SRM 610 and the USGS basaltic glasses BHVO‐2G, BIR‐1G and BCR‐2G, and utilising 43Ca as an internal standard. Analyses of the MPI‐DING reference glasses, which represent geological matrices ranging from basaltic to rhyolitic in composition, included measurements of concentrations as low as < 100 μg g?1 and as high as > 104 μg g?1. The new data reported here were found to statistically correlate with the ‘preferred’ reference values for these materials at the 95% confidence level, though with significantly better precision, typically on the order of ≤ 3% (2sm). This analytical method may be extended to any matrix‐matched geological sample, particularly oceanic basalts, silicate minerals and meteoritic materials.  相似文献   

8.
We report an approach for the accurate and reproducible measurement of boron isotope ratios in natural waters using an MC‐ICP‐MS (Neptune) after wet chemistry sample purification. The sample matrix can induce a drastic shift in the isotopic ratio by changing the mass bias. It is shown that, if no purification is carried out, the direct measurement of a seawater diluted one hundred times will induce an offset of ?7‰ in the isotopic ratio, and that, for the same concentration, the greater the atomic mass of the matrix element, the greater the bias induced. Whatever the sample, it is thus necessary to remove the matrix. We propose a method adapted to water samples allowing purification of 100 ng of boron with a direct recovery of boron in 2 ml of 3% v/v HNO3, which was our working solution. Boron from the International Atomic Energy Agency IAEA‐B1 seawater reference material and from the two groundwater reference materials IAEA‐B2 and IAEA‐B3, was chemically purified, as well as boron from the certified reference material NIST SRM 951 as a test. The reproducibility of the whole procedure (wet chemistry and MC‐ICP‐MS measurement) was ± 0.4‰ (2s). Accuracy was verified by comparison with positive‐TIMS values and with recommended values. Seawater, being homogeneous for boron isotope ratios, is presently the only natural water material that is commonly analysed for testing accuracy worldwide. We propose that the three IAEA natural waters could be used as reference samples for boron isotopes, allowing a better knowledge of their isotopic ratios, thus contributing to the certification of methods and improving the quality of the boron isotopic ratio measurements for all laboratories.  相似文献   

9.
Mg/Ca and Sr/Ca ratios in calcium carbonate are important components of many palaeoclimate studies. We present an isotope dilution method relying on a single mixed spike containing 25Mg, 43Ca and 87Sr. Dozens of samples per day, as small as 10 μg of carbonate, could be dissolved, spiked and run in an ICP‐MS with a precision of 0.8% (2 RSD). Two instruments types, a sector field and a quadrupole ICP‐MS, were compared. The best long term precision found was 0.4% (2 RSD), although this increased by up to a factor of two when samples of very different Mg or Sr content were run together in the same sequence. Long term averages for the two instruments concurred. No matrix effects were detected for a range of Ca concentrations between 0.2 and 2 mmol l‐1. Accuracy, tested by measuring synthetic standard solutions, was 0.8% with some systematic trends. We demonstrate the strength of this isotope dilution method for (a) obtaining accurate results for sample sets that present a broad Mg and Sr range and (b) testing solid carbonates as candidate reference materials for interlaboratory consistency. Mg/Ca and Sr/Ca results for reference materials were in good agreement with values from the literature.  相似文献   

10.
We present a revised alkali fusion method for the determination of trace elements in geological samples. Our procedure is based on simple acid digestion of powdered low‐dilution (flux : sample ≈ 2 : 1) glass beads where large sample dilution demanded by high total dissolved solids, a main drawback of conventional alkali fusion, could be circumvented. Three geological reference materials (G‐3 granite, GSP‐2 granodiorite and SGD‐1a gabbro) decomposed by this technique and routine tabletop acid digestion were analysed for thirty trace elements using a quadrupole ICP‐MS. Results by conventional acid digestion distinctly showed poor recoveries of Zr, Hf and rare earth elements due to incomplete dissolution of resistant minerals. On the other hand, results obtained by our method were in reasonable agreement with reference data for most analytes, indicating that refractory minerals were efficiently dissolved and volatile loss was insignificant.  相似文献   

11.
Two Co‐rich seamount crust reference materials, MCPt‐1 and MCPt‐2, were prepared using ultra‐fine particle size milling technique and characterised for the platinum‐group elements (PGEs). The raw material for these two reference materials was collected separately from the Magellan seamounts of the western Pacific Ocean and the seamounts of the central Pacific Ocean by Russian and Chinese scientists. First, they were ground by ball mill to a ?200 mesh powder, then further processed by ultra‐fine jet mill and well‐mixed. The particle size distributions of the samples were tested by a laser particle analyser; the average particle size was 1.8 and 1.5 μm (equal to about 2000 mesh) respectively. The homogeneity of six major and minor elements in these two materials was tested at the milligram level of sampling mass by high‐precision wavelength dispersive X‐ray fluorescence (XRF) spectrometry and at the microgram level of sampling mass by electron probe microanalyser. The homogeneity of more than forty trace elements, including Pt, was tested at the microgram level of sampling mass by LA‐ICP‐MS. Except for Rh, all PGEs were determined by isotope dilution‐ICP‐MS. Platinum in MCPt‐1 and MCPt‐2 was characterised as certified values, whereas the other five PGEs in MCPt‐1 and MCPt‐2 were reported as reference values. In addition, the information values of sixty‐two major, minor and trace elements were obtained by XRF, ICP‐AES and ICP‐MS. The minimum sampling mass for the determination of PGEs was 1 g, while the minimum sampling mass for the determination of the other elements was 2–5 mg.  相似文献   

12.
Fused glass prepared without the addition of a flux is generally more homogeneous than a pressed powder pellet and thus ideal for analysis of bulk samples by LA‐ICP‐MS. In this work, a new glass‐making method using a boron nitride crucible was developed to prepare homogenous glass samples from silicate rock powder. The apparatus consisted of a small boron nitride vessel with net volume of about 34 mm3 and two molybdenum strips. Applying the summed metal oxide normalisation technique, both major and trace element contents in the fused glass were measured by LA‐ICP‐MS. Analyses of five geochemical reference materials (spanning the compositional range basalt–andesite–rhyolite) indicated that the measured SiO2, Al2O3 and P2O5 contents matched the preferred values to within 5%, and the other major elements generally matched the preferred values to within 8%. Except for the transition metals, the measured trace element contents generally matched the preferred values to within 10%. Compared with the iridium heater method developed by Stoll et al. (2008), element volatilisation during high‐temperature melting was effectively suppressed in our method, but metal segregation caused by reduction of BN may cause loss of Cr, Ni and Cu. Although analysis with a large spot size has the advantage of improving counting statistics, matrix effects induced by mass loading of the ICP may hamper the accurate determination of some elements.  相似文献   

13.
This study describes two methods (Procedures‐1 and ‐2) for the direct extraction of Au by an inorganic acid mixture (HClO4‐HBr‐HI‐aqua regia) from complex sample matrices. Standard PTFE jars at 200 °C were used to decompose test portions of 0.5–1 g, with subsequent precise and accurate analysis by ICP‐MS without any other preconcentration or separation. Procedure‐1 decomposed samples effectively without the necessity of leaching with HF and was developed for dust samples from e‐waste (electronic waste) processing; however, testing on geological reference materials showed very good results. The analyses of replicate decompositions (n = 5) from both procedures yielded very good precision (< 5% RSD) for most of the reference materials. The accuracy achieved was better than ± 10%, with the exception of NIST SRM 2782 data from Procedure‐1. Two unknown samples of dust from e‐waste processing (P‐1 and VM‐1) exhibited elevated concentrations of Au (21.31–61.64 μg g?1) with precision better than 10% (n = 5). The proposed techniques are simple, sensitive and sparing in the use of chemicals, and are designed for a variety of e‐waste dust samples. No significant influences were observed for the predicted spectral interferences on mass 197Au.  相似文献   

14.
We report an improved procedure for the determination of the platinum‐group elements (PGE) and Re, and Os isotopes from a single sample aliquot by isotope dilution (ID) using inductively coupled plasma‐mass spectrometry (ICP‐MS) and negative thermal ionisation mass spectrometry (N‐TIMS), respectively. A two‐stage column method was used to purify PGE‐Re from their sample matrix and interfering elements (e.g., Mo, Zr and Hf) after Os had been separated by CCl4 solvent extraction. The first column separation step used cation exchange resin (AG50W‐X8) to concentrate PGE‐Re and some potential interfering elements (e.g., Mo, Zr and Hf). In the second step, N‐benzoyl‐N‐phenylhydroxylamine (BPHA) extraction resin was used to separate PGE‐Re from the remaining interfering elements, which all remained strongly absorbed to the resin. The method was used to determine the PGE and rhenium, and Os isotope ratios in a range of geochemical reference materials (TDB‐1, WGB‐1, BHVO‐2 and UB‐N). The obtained results agree well with those previously published. This new method enables PGE‐Re abundances and Os isotopic ratios to be determined on the same sample digestion, and circumvents the problems created by sample heterogeneity when comparing PGE and Re‐Os isotope data.  相似文献   

15.
A simple, rapid method for the determination of Re and Os concentrations and isotope compositions using isotope dilution multi‐collector inductively coupled plasma‐mass spectrometry (ID‐MC‐ICP‐MS) combined with Carius tube digestion and sparging introduction of Os was developed. For Os measurement, four channeltron ion counters to detect different Os isotopes were used simultaneously, which led to a drastic reduction in the measurement time. Rhenium isotopes were measured by means of eight Faraday cups with solution nebulisation and an ultrasonic membrane desolvator. The representative 188Os count rate of an Os standard solution containing 50 pg of total Os was approximately 110000–120000 cps at the onset of measurement; the Re intensity of our in‐house 10 pg g?1 standard solution reached 1820 V/μg g?1 with a sample uptake rate of 95–99 μl min?1. These values indicate that the sensitivity of the method was sufficient even for samples with low Re and Os concentrations, such as chert. As the temporal variations of the amplification efficiency of the ion counters differed from one another, we adopted a sample‐calibrator bracketing method to correct the measured Re and Os isotope ratios. The Re and Os concentrations via the isotope dilution method and the 187Os/188Os ratios of two sedimentary rock reference materials (JMS‐2 and JCh‐1) on the basis of the isotope ratios determined by the MC‐ICP‐MS and by negative thermal ionisation mass spectrometry (N‐TIMS) were comparable within their ranges. Based on Os isotope measurement of the IAG reference material [Durham Romil Os (DROsS)], the average difference from the recommended value and precision of Os isotope measurements by the sparging method in combination with multi‐ion‐counters were 0.72% and 0.76% [1RSD (%), n = 29], respectively. The precisions in the 187Os/188Os ratios [1RSD (%)] of JMS‐2, JCh‐1 and DROsS were 0.35–0.71, 1.56–3.31 and 0.99–1.28%, respectively, which depended on their Os ion intensities. No systematic difference was observed between the Re and Os geochemical compositions of JCh‐1 and JMS‐2 obtained by means of digestion with inverse aqua regia and CrO3‐H2SO4 solutions, suggesting that either acid solution can be used for the sparging method of sedimentary rock samples. As CrO3‐H2SO4 solution is believed to liberate predominantly the hydrogenous Re and Os fraction from organic‐rich sediment, the sparging method combined with CrO3‐H2SO4 digestion and multi‐ion‐counters in the mass spectrometry is expected to be a powerful tool for reconstructing the secular change in marine Os isotope compositions with high sample throughput.  相似文献   

16.
With implications for the origin of ore deposits, redox state of the atmosphere, and effects of volcanic outgassing, understanding the sulfur cycle is vital to our investigation of Earth processes. However, the paucity of sulfur concentration measurements in silicate rocks and the lack of well‐calibrated reference materials with concentrations relevant to the rocks of interest have hindered such investigations. To aid in this endeavour, this study details a new method to determine sulfur concentration via high mass resolution solution inductively coupled plasma‐mass spectrometry (ICP‐MS). The method is based on an aqua regia leach, involving relatively rapid sample preparation and analysis, and uses small test portion masses (< 50 mg). We utilised two independently prepared standard solutions to calibrate the analyses, resulting in 4% accuracy, and applied the method to eight geochemical reference materials. Measurements were reproducible to within ~ 10%. Sulfur concentrations and isotopes of six reference materials were measured additionally by elemental analyser‐combustion‐isotope ratio mass spectrometry to independently evaluate the accuracy of the ICP‐MS method. Reference materials that yielded reproducible measurements identical to published values from other laboratories (JGb‐1, JGb‐2 and MAG‐1) are considered useful materials for the measurement of sulfur. Reference materials that varied between studies but were reproducible for a given test portion perhaps suffer from sample heterogeneity and are not recommended as sulfur reference materials.  相似文献   

17.
Gold and copper concentrations were determined in natural pyrite by near‐infrared femtosecond LA‐ICP‐QMS, using both sulfide reference materials (pyrrhotite Po‐726 and in‐house natural chalcopyrite Cpy‐RM) and NIST SRM 610 as external calibrators. Firstly, using NIST SRM 610 as the external calibrator, we calculated the Au concentration in Po‐726 and the Cu concentration in Cpy‐RM. The calculated concentration averages for Au and Cu were similar to the values published for Po‐726 and Cpy‐RM, respectively. Secondly, we calculated Au and Cu concentrations taking NIST SRM 610 as an unknown sample and using Po‐726 and Cpy‐RM as external calibrators. Again, the average values obtained closely reflected the preferred concentrations for NIST SRM 610. Finally, we calculated Au and Cu concentrations in natural pyrite using sulfide and silicate reference materials as external calibrators. In both cases, calculated concentrations were very similar, independent of the external calibrator used. The aforementioned data, plus the fact that we obtained very small differences in relative sensitivity values (percentage differences are between 5% and 17% for 57Fe, 63Cu and 197Au) on analyses of silicate and sulfide RMs, indicate that there were no matrix effects related to the differences in material composition. Thus, it is possible to determine Au and Cu in natural sulfides using NIST silicate glasses as an external calibrator.  相似文献   

18.
Lead isotope ratio data were obtained with good precision and accuracy using a 266 nm femtosecond laser ablation (fLA) system connected to a multi‐collector ICP‐MS (MC‐ICP‐MS) and through careful control of analytical procedures. The mass fractionation coefficient induced by 266 nm femtosecond laser ablation was approximately 28% lower than that by 193 nm excimer laser ablation (eLA) with helium carrier gas. The exponential law correction method for Tl normalisation with optimum adjusted Tl ratio was utilised to obtain Pb isotopic data with good precision and accuracy. The Pb isotopic ratios of the glass reference materials NIST SRM 610, 612, 614; USGS BHVO‐2G, BCR‐2G, GSD‐1G, BIR‐1G; and MPI‐DING GOR132‐G, KL2‐G, T1‐G, StHs60/80‐G, ATHO‐G and ML3B‐G were determined using fLA‐MC‐ICP‐MS. The measured Pb isotopic ratios were in good agreement with the reference or published values within 2s measurement uncertainties. We also present the first high‐precision Pb isotopic data for GSE‐1G, GSC‐1G, GSA‐1G and CGSG‐1, CGSG‐2, CGSG‐4 and CGSG‐5 glass reference materials obtained using the femtosecond laser ablation MC‐ICP‐MS analysis technique.  相似文献   

19.
A method for the determination of total sulfur in geological materials by inductively coupled plasma‐optical emission spectrometry (ICP‐OES) is described. We show that good results were obtained using this method even for sample types with very low (< 20 μg g?1) sulfur concentration (e.g., peridotite). Sulfur was determined in fifteen geological reference materials with different sulfur contents. For reference materials with certified sulfur contents, the ICP‐OES method gave results in excellent agreement with certified values, and uncertainties better than 4% RSD. ICP‐OES results for sulfur in other reference materials yielded RSDs better than 10%, where S concentrations were > 100 μg g?1 (except for diabase W‐2a, 16% RSD). Reference materials with lower sulfur contents (< 40 μg g?1) showed much higher RSDs (17–18%). Except for RMs with certified values for sulfur, most data obtained by the combustion infrared detection method generally showed higher concentrations than those measured by ICP‐OES and a better RSD (≤ 8% for all materials except DTS‐2b).  相似文献   

20.
The Lamont‐Doherty Earth Observatory radiogenic isotope group has been systematically measuring Sr‐Nd‐Pb‐Hf isotopes of USGS reference material BCR‐2 (Columbia River Basalt 2), as a chemical processing and instrumental quality control monitor for isotopic measurements. BCR‐2 is now a widely used geochemical inter‐laboratory reference material (RM), with its predecessor BCR‐1 no longer available. Recognising that precise and accurate data on RMs is important for ensuring analytical quality and for comparing data between different laboratories, we present a compilation of multiple digestions and analyses made on BCR‐2 during the first author's dissertation research. The best estimates of Sr, Nd and Hf isotope ratios and measurement reproducibilities, after filtering at the 2s level for outliers, were 87Sr/86Sr = 0.705000 ± 11 (2s, 16 ppm, n = 21, sixteen digestions, one outlier), 143Nd/144Nd = 0.512637 ± 13 (2s, 25 ppm, n = 27, thirteen digestions, one outlier) and 176Hf/177Hf = 0.282866 ± 11 (2s, 39 ppm, n = 25, thirteen digestions, no outliers). Mean Nd and Hf values were within error of those reported by Weis et al. (2006, 2007) in their studies of RMs; mean Sr values were just outside the 2s uncertainty range of both laboratories. Moreover, a survey of published Sr‐Nd‐Hf data shows that our results fall within the range of reported values, but with a smaller variability. Our Pb isotope results on acid leached BCR‐2 aliquots (n = 26, twelve digestions, two outliers) were 206Pb/204Pb = 18.8029 ± 10 (2s, 55 ppm), 207Pb/204Pb = 15.6239 ± 8 (2s, 52 ppm), 208Pb/204Pb = 38.8287 ± 25 (2s, 63 ppm). We confirm that unleached BCR‐2 powder is contaminated with Pb, and that sufficient leaching prior to digestion is required to achieve accurate values for the uncontaminated Pb isotopic compositions.  相似文献   

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