Characterisation of a Natural Quartz Crystal as a Reference Material for Microanalytical Determination of Ti,Al, Li,Fe, Mn,Ga and Ge

A natural smoky quartz crystal from Shandong province, China, was characterised by laser ablation ICP‐MS, electron probe microanalysis (EPMA) and solution ICP‐MS to determine the concentration of twenty‐four trace and ultra trace elements. Our main focus was on Ti quantification because of the increased use of this element for titanium‐in‐quartz (TitaniQ) thermobarometry. Pieces of a uniform growth zone of 9 mm thickness within the quartz crystal were analysed in four different LA‐ICP‐MS laboratories, three EPMA laboratories and one solution‐ICP‐MS laboratory. The results reveal reproducible concentrations of Ti (57 ± 4 μg g^?1), Al (154 ± 15 μg g^?1), Li (30 ± 2 μg g^?1), Fe (2.2 ± 0.3 μg g^?1), Mn (0.34 ± 0.04 μg g^?1), Ge (1.7 ± 0.2 μg g^?1) and Ga (0.020 ± 0.002 μg g^?1) and detectable, but less reproducible, concentrations of Be, B, Na, Cu, Zr, Sn and Pb. Concentrations of K, Ca, Sr, Mo, Ag, Sb, Ba and Au were below the limits of detection of all three techniques. The uncertainties on the average concentration determinations by multiple techniques and laboratories for Ti, Al, Li, Fe, Mn, Ga and Ge are low; hence, this quartz can serve as a reference material or a secondary reference material for microanalytical applications involving the quantification of trace elements in quartz.     

A Rapid Method for Determining Boron Concentration (ID‐ICP‐MS) and δ11B (MC‐ICP‐MS) in Vegetation Samples after Microwave Digestion and Cation Exchange Chemical Purification

We present in this article a rapid method for B extraction, purification and accurate B concentration and δ¹¹B measurements by ID‐ICP‐MS and MC‐ICP‐MS, respectively, in different vegetation samples (bark, wood and tree leaves). We developed a rapid three‐step procedure including (1) microwave digestion, (2) cation exchange chromatography and (3) microsublimation. The entire procedure can be performed in a single working day and has shown to allow full B recovery yield and a measurement repeatability as low as 0.36‰ (± 2s) for isotope ratios. Uncertainties mostly originate from the cation exchange step but are independent of the nature of the vegetation sample. For δ¹¹B determination by MC‐ICP‐MS, the effect of chemical impurities in the loading sample solution has shown to be critical if the dissolved load exceeds 5 μg g^?1 of total salts or 25 μg g^?1 of DOC. Our results also demonstrate that the acid concentration in the sample loading solution can also induce critical isotopic bias by MC‐ICP‐MS if chemistry of the rinsing‐, bracketing calibrator‐ and sample solutions is not thoroughly adjusted. We applied this method to provide a series of δ¹¹B values of vegetal reference materials (NIST SRM 1570a = 25.74 ± 0.21‰; NIST 1547 = 40.12 ± 0.21‰; B2273 = 4.56 ± 0.15‰; BCR 060 = ?8.72 ± 0.16‰; NCS DC73349 = 16.43 ± 0.12‰).     

Determination of Boron Concentration in Geochemical Reference Materials Extracted by Pyrohydrolysis and Measured by ICP‐MS

This article presents new boron concentrations for nine geochemical reference materials (GS‐N, FK‐N, GL‐O, BX‐N, DT‐N, AN‐G, GH, Mica‐Fe, Mica‐Mg). After extraction by a modified pyrohydrolysis technique, boron concentrations were measured by ICP‐MS. The blank levels for the whole procedure were 0.091 ± 0.020 ng ml^?1 or 14 ± 5 ng of boron in total. The method was first validated by measuring nine reference materials with known boron concentrations. The determined boron concentrations are all within the range of recommended or published values, which means that the yields were 100%, and show precisions below 10% for samples containing over 2 μg g^?1 of boron.     

A New LA‐ICP‐MS Method for Ti in Quartz: Implications and Application to High Pressure Rutile‐Quartz Veins from the Czech Erzgebirge

Experimental determination of the pressure and temperature controls on Ti solubility in quartz provides a calibration of the Ti‐in‐quartz (TitaniQ) geothermometer applicable to geological conditions up to ~ 20 kbar. We present a new method for determining ⁴⁸Ti mass fractions in quartz by LA‐ICP‐MS at the 1 μg g^?1 level, relevant to quartz in HP‐LT terranes. We suggest that natural quartz such as the low‐CL rims of the Bishop Tuff quartz (determined by EPMA; 41 ± 2 μg g^?1 Ti, 2s) is more suitable than NIST reference glasses as a reference material for low Ti mass fractions because matrix effects are limited, Ca isobaric interferences are avoided, and polyatomic interferences at mass 48 are insignificant, thus allowing for the use of ⁴⁸Ti as a normalising mass. Average titanium mass fraction from thirty‐three analyses of low temperature quartz from the Czech Erzgebirge is 0.9 ± 0.2 μg g^?1 (2s) using ⁴⁸Ti as a normalising mass and Bishop Tuff quartz rims as a reference material. The 2s average analytical uncertainty for individual analyses of ⁴⁸Ti is 8% for 50 μm spots and 7% for 100 μm spots, which offers much greater accuracy than the 21–41% uncertainty (2s) incurred from using ⁴⁹Ti as an analyte.     

A New Appraisal of Sri Lankan BB Zircon as a Reference Material for LA‐ICP‐MS U‐Pb Geochronology and Lu‐Hf Isotope Tracing

A potential zircon reference material (BB zircon) for laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) U‐Pb geochronology and Hf isotope geochemistry is described. A batch of twenty zircon megacrysts (0.5–1.5 cm³) from Sri Lanka was studied. Within‐grain rare earth element (REE) compositions are largely homogeneous, albeit with some variation seen between fractured and homogeneous domains. Excluding fractured cathodoluminescence bright domains, the variation in U content for all analysed crystals ranged from 227 to 368 μg g^?1 and the average Th/U ratios were between 0.20 and 0.47. The Hf isotope composition (0.56–0.84 g/100 g Hf) is homogeneous within and between the grains – mean ¹⁷⁶Hf/¹⁷⁷Hf of 0.281674 ± 0.000018 (2s). The calculated alpha dose of 0.59 × 10¹⁸ g^?1 for a number of BB grains falls within the trend of previously studied, untreated zircon samples from Sri Lanka. Aliquots of the same crystal (analysed by ID‐TIMS in four different laboratories) gave consistent U‐Pb ages with excellent measurement reproducibility (0.1–0.4% RSD). Interlaboratory assessment (by LA‐ICP‐MS) from individual crystals returned results that are within uncertainty equivalent to the TIMS ages. Finally, we report on within‐ and between‐grain homogeneity of the oxygen isotope systematic of four BB crystals (13.16‰ VSMOW).     

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).     

Rutile R632 – A New Natural Reference Material for U‐Pb and Zr Determination

A new natural rutile reference material is presented, suitable for U‐Pb dating and Zr‐in‐rutile thermometry by microbeam methods. U‐Pb dating of rutile R632 using laser ablation ICP‐MS with both magnetic sector field and quadrupole instruments as well as isotope dilution‐thermal ionisation mass spectrometry yielded a concordia age of 496 ± 2 Ma. The high U content (> 300 μg g^?1) enabled measurement of high‐precision U‐Pb ages despite its young age. The sample was found to have a Zr content of 4294 ± 196 μg g^?1, which makes it an excellent complementary reference material for Zr‐in‐rutile thermometry. Individual rutile grains have homogeneous compositions of a number of other trace elements including V, Cr, Fe, Nb, Mo, Sn, Sb, Hf, Ta and W. This newly characterised material significantly expands the range of available rutile reference materials relevant for age and temperature determinations.     

Niobium and Tantalum Concentrations in NIST SRM 610 Revisited

Niobium and Ta concentrations in MPI‐DING and USGS (BCR‐2G, BHVO‐2G, BIR‐1G) silicate rock glasses and the NIST SRM 610–614 synthetic soda‐lime glasses were determined by 193 nm ArF excimer laser ablation and quadrupole ICP‐MS. Measured Nb and Ta values of MPI‐DING glasses were found to be consistently lower than the recommended values by about 15% and 25%, respectively, if calibration was undertaken using commonly accepted values of NIST SRM 610 given by Pearce et al. Analytical precision, as given by the 1 s relative standard deviation (% RSD) was less than 10% for Nb and Ta at concentrations higher than 0.1 μg g^?1. A significant negative correlation was found between logarithmic concentration and logarithmic RSD, with correlation coefficients of ‐0.94 for Nb and ‐0.96 for Ta. This trend indicates that the analytical precision follows counting statistics and thus most of the measurement uncertainty was analytical in origin and not due to chemical heterogeneities. Large differences between measured and expected Nb and Ta in glasses GOR128‐G and GOR132‐G are likely to have been caused by the high RSDs associated with their very low concentrations. However, this cannot explain the large differences between measured and expected Nb and Ta in other MPI‐DING glasses, since the differences are normally higher than RSD by a factor of 3. Count rates for Nb and Ta, normalised to Ca sensitivity, for the MPI‐DING, USGS and NIST SRM 612–614 glasses were used to construct calibration curves for determining NIST SRM 610 concentrations at crater diameters ranging from 16 (im to 60 μm. The excellent correlation between the Nb/Ca_1μgg‐1 signal (Nb represents the Nb signal intensity; Ca_{1μg g‐1} represents the Ca sensitivity) and Nb concentration, and between the Ta/Ca_{1μg g‐1} signal (where Ta represents the Ta signal intensity; Ca_{1μg g‐1} represents the Ca sensitivity) and Ta concentration (R²= 0.9992–1.00) in the various glass matrices suggests that matrix‐dependent fractionation for Nb, Ta and Ca was insignificant under the given instrumental conditions. The results confirm that calibration reference values of Nb and Ta in NIST SRM 610 given by Pearce et al. are about 16% and 28% lower, respectively. We thus propose a revision of the preferred value for Nb from 419.4 ± 57.6 μg g^?1 to 485 ± 5 μg g^?1 (1 s) and for Ta from 376.6 ± 77.6 μg g^?1 to 482 ± 4 μg g^?1 (Is) in NIST SRM 610. Using these revised values for external calibration, most of the determined average values of MPI‐DING, USGS and NIST SRM 612–614 reference glasses agree within 3% with the calculated means of reported reference values. Bulk analysis of NIST SRM 610 by standard additions using membrane desolvation ICP‐MS gave Nb = 479 ± 6 μg g^?1 (1 s) and Ta = 468 ± 7 μg g^?1 (1 s), which agree with the above revised values within 3%.     

Characterisation of Apatites as Potential Uranium Reference Materials for Fission‐track Dating by LA‐ICP‐MS

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.     

Boron Isotope Analysis of Silicate Glass with Very Low Boron Concentrations by Secondary Ion Mass Spectrometry

We present an improved method for the determination of the boron isotopic composition of volcanic glasses with boron concentrations of as low as 0.4–2.5 μg g^?1, as is typical for mid‐ocean ridge basalt glasses. The analyses were completed by secondary ion mass spectrometry using a Cameca 1280 large‐radius ion microprobe. Transmission and stability of the instrument and analytical protocol were optimised, which led to an improvement of precision and reduction in surface contamination and analysis time compared with earlier studies. Accuracy, reproducibility (0.4–2.3‰, 2 RSD), measurement repeatability (2 RSE = 2.5–4.0‰ for a single spot with [B] = 1 μg g^?1), matrix effects (? 0.5‰ among komatiitic, dacitic and rhyolitic glass), machine drift (no internal drift; long‐term drift: ~ 0.1‰ hr^?1), contamination (~ 3–8 ng g^?1) and machine background (0.093 s^?1) were quantified and their influence on samples with low B concentrations was determined. The newly developed set‐up was capable of determining the B isotopic composition of basaltic glass with 1 μg g^?1 B with a precision and accuracy of ± 1.5‰ (2 RSE) by completing 4–5 consecutive spot analyses with a spatial resolution of 30 μm × 30 μm. Samples with slightly higher concentrations (≥ 2.5 μg g^?1) could be analysed with a precision of better than ± 2‰ (internal 2 RSE) with a single spot analysis, which took 32 min.     

Accurate Determination of Sr Isotopic Compositions in Clinopyroxene and Silicate Glasses by LA‐MC‐ICP‐MS

The low‐Sr content (generally < 100 μg g^?1) in clinopyroxene from peridotite makes accurate Sr isotopic determination by LA‐MC‐ICP‐MS a challenge. The effects of adding N₂ to the sample gas and using a guard electrode (GE) on instrumental sensitivity for Sr isotopic determination by LA‐MC‐ICP‐MS were investigated. Results revealed no significant sensitivity enhancement of Sr by adding N₂ to the ICP. Although using a GE led to a two‐fold sensitivity enhancement, it significantly increased the yield of polyatomic ion interferences of Ca‐related ions and TiAr⁺ on Sr isotopes. Applying the method established in this work, ⁸⁷Sr/⁸⁶Sr ratios (Rb/Sr < 0.14) of natural clinopyroxene from mantle and silicate glasses were accurately measured with similar measurement repeatability (0.0009–0.00006, 2SE) to previous studies but using a smaller spot size of 120 μm and low‐to‐moderate Sr content (30–518 μg g^?1). The measurement reproducibility was 0.0004 (2s, n = 33) for a sample with 100 μg g^?1 Sr. Destruction of the crystal structure by sample fusion showed no effect on Sr isotopic determination. Synthesised glasses with major element compositions similar to natural clinopyroxene have the potential to be adopted as reference materials for Sr isotopic determination by LA‐MC‐ICP‐MS.     

Zircon M127 – A Homogeneous Reference Material for SIMS U–Pb Geochronology Combined with Hafnium,Oxygen and,Potentially, Lithium Isotope Analysis

In this article, we document a detailed analytical characterisation of zircon M127, a homogeneous 12.7 carat gemstone from Ratnapura, Sri Lanka. Zircon M127 has TIMS‐determined mean U–Pb radiogenic isotopic ratios of 0.084743 ± 0.000027 for ²⁰⁶Pb/²³⁸U and 0.67676 ± 0.00023 for ²⁰⁷Pb/²³⁵U (weighted means, 2s uncertainties). Its ²⁰⁶Pb/²³⁸U age of 524.36 ± 0.16 Ma (95% confidence uncertainty) is concordant within the uncertainties of decay constants. The δ¹⁸O value (determined by laser fluorination) is 8.26 ± 0.06‰ VSMOW (2s), and the mean ¹⁷⁶Hf/¹⁷⁷Hf ratio (determined by solution ICP‐MS) is 0.282396 ± 0.000004 (2s). The SIMS‐determined δ⁷Li value is ?0.6 ± 0.9‰ (2s), with a mean mass fraction of 1.0 ± 0.1 μg g^?1 Li (2s). Zircon M127 contains ~ 923 μg g^?1 U. The moderate degree of radiation damage corresponds well with the time‐integrated self‐irradiation dose of 1.82 × 10¹⁸ alpha events per gram. This observation, and the (U–Th)/He age of 426 ± 7 Ma (2s), which is typical of unheated Sri Lankan zircon, enable us to exclude any thermal treatment. Zircon M127 is proposed as a reference material for the determination of zircon U–Pb ages by means of SIMS in combination with hafnium and stable isotope (oxygen and potentially also lithium) determination.     

A Matrix‐Matched Reference Material for Validating Petroleum Re‐Os Measurements

This study presents two matrix‐matched reference materials developed for petroleum Re‐Os measurements. We present the Re and Os mass fractions and ¹⁸⁷Re/¹⁸⁸Os and ¹⁸⁷Os/¹⁸⁸Os values (ratio of the number of atoms of the isotopes) for repeatedly measured aliquots (ca. 120–150 mg test portions) of the NIST Research Material 8505 (RM 8505) crude oil, and its asphaltene and maltene fractions, and ~ 90 g of homogeneous asphaltene powder isolated from this oil. Measurements were performed using the Carius tube‐isotope dilution negative‐thermal ionisation mass spectrometry methodology. The RM 8505 crude oil contains 1.98 ± 0.07 ng g^?1 Re and 25.0 ± 1.1 pg g^?1 Os, with Re‐Os isotope amount ratios of 452 ± 6 for ¹⁸⁷Re/¹⁸⁸Os and 1.51 ± 0.01 for ¹⁸⁷Os/¹⁸⁸Os (n = 20, 95% conf.). The homogeneous asphaltene sample contains 16.52 ± 0.10 ng g^?1 Re and 166.0 ± 0.9 pg g^?1 total Os, and possesses isotope amount ratios of 574 ± 3 for ¹⁸⁷Re/¹⁸⁸Os and 1.64 ± 0.01 for ¹⁸⁷Os/¹⁸⁸Os (n = 24, 95% conf.). The intermediate precision of these data makes the RM 8505 whole oil and the (~ 90 g) homogenised asphaltene appropriate petroleum matrix‐matched reference materials for Re‐Os measurements. The asphaltene fraction of the oil is the main carrier of Re and Os of the RM 8505 whole oil, and caution is suggested in using asphaltene and maltene fractions of a single oil for Re‐Os geochronology.     

RMJG Rutile: A New Natural Reference Material for Microbeam U‐Pb Dating and Hf Isotopic Analysis

Matrix‐matched reference materials are necessary for accurate microbeam U‐Pb dating and Hf isotopic determination. This study introduces the RMJG rutile as a new potential reference material, which was separated from Palaeoproterozoic pelitic granulites collected in Hebei Province, China. LA‐ICP‐MS measurements indicate the RMJG rutile has extremely low Th (< 0.003 ± 0.01 µg g^?1) and common Pb contents, but high Hf (102 ± 34 µg g^?1), U (61 ± 11 µg g^?1), and radiogenic Pb (~ 20 µg g^?1) contents. Moreover, the rutile yields relatively constant U‐Pb ages and Hf isotopic data. The LA‐ICP‐MS analyses suggest that this rutile has a concordant U‐Pb age with a statistical mean ²⁰⁶Pb/²³⁸U and ²⁰⁷Pb/²³⁵U ages of 1749.9 ± 32.1 Ma and 1750.0 ± 26.4 Ma, respectively (2s), which are statistically indistinguishable from its ID‐TIMS ages (1750.6 ± 8.4 and 1750.1 ± 4.7 Ma). Precise determination of the ¹⁷⁶Hf/¹⁷⁷Hf ratio by MC‐ICP‐MS in solution mode (0.281652 ± 0.000006) is in good agreement with the statistical mean of the LA‐MC‐ICP‐MS measurements (0.28166 ± 0.00018). Therefore, the limited variations of RMJG U‐Pb age and Hf isotopic composition together with its extremely low common Pb and high Hf, U and Pb contents make it an ideal calibration and monitor reference material for LA‐ICP‐MS measurements.     

Electron Probe Microanalysis of Bromine in Minerals and Glasses with Correction for Spectral Interference from Aluminium,and Comparison with Microbeam Synchrotron X‐Ray Fluorescence Spectrometry

The strong spectral interference between Br‐ and Al‐induced X‐ray lines hampers the utilisation of electron probe microanalysis (EPMA) for measuring Br mass fractions in Al‐bearing minerals and glasses. Through measuring Br‐free Al‐bearing materials, we established an EPMA method to quantify the overlap from AlKα on BrLβ, which can be expressed as a linear function of the Al₂O₃ content. The count rate of the BrLβ peak signal was enhanced by high beam currents and long measurement times. Application of this EPMA method to Al‐ and Br‐bearing materials, such as sodalite and scapolite, and to five experimental glasses yielded Br mass fractions (in the range of 250–4000 μg g^?1) that are consistent with those measured by microbeam synchrotron X‐ray fluorescence (μ‐SXRF) spectrometry. The EPMA method has an estimated detection limit of ~ 100–300 μg g^?1. We propose that this method is useful for measuring Br mass fractions (hundreds to thousands of μg g^?1) in Al‐bearing minerals and glasses, including those produced in Br‐doped experiments. In addition, the natural marialitic scapolite (ON70) from Mpwapwa (Tanzania) containing homogeneously distributed high mass fractions of Br (2058 ± 56 μg g^?1) and Cl (1.98 ± 0.03% m/m) is an ideal reference material for future in situ analyses.     

Molybdenum Mass Fractions and Stable Isotope Compositions of Sedimentary Carbonate and Silicate Reference Materials

A double‐spike method in combination with MC‐ICP‐MS was applied to obtain molybdenum (Mo) mass fractions and stable isotope compositions in a suite of sedimentary silicate (marine, lake, stream, estuarine, organic‐rich sediment, shales, slate, chert) and carbonate reference materials (coral, dolomite, limestones, carbonatites), and a manganese nodule reference material, poorly characterised for stable Mo isotope compositions. The Mo contents vary between 0.076 and 364 μg g^?1, with low‐Mo mass fractions (< 0.29 μg g^?1) found almost exclusively in carbonates. Intermediate Mo contents (0.73–2.70 μg g^?1) are reported for silicate sediments, with the exception of chert JCh‐1 (0.24 μg g^?1), organic‐rich shale SGR‐1b (36.6 μg g^?1) and manganese nodule NOD‐A‐1 (364 μg g^?1). The Mo isotope compositions (reported as δ⁹⁸Mo relative to NIST SRM 3134) range from ?1.77 to 1.03‰, with the intermediate precision varying between ± 0.01 and ± 0.12‰ (2s) for most materials. Low‐temperature carbonates show δ⁹⁸Mo values ranging from 0.21 to 1.03‰ whereas δ⁹⁸Mo values of ?1.77 and ?0.17‰ were obtained for carbonatites CMP‐1 and COQ‐1, respectively. Silicate materials have δ⁹⁸Mo values varying from ?1.56 to 0.73‰. The range of δ⁹⁸Mo values in reference materials may thus reflect the increasingly important relevance of Mo isotope investigations in the fields of palaeoceanography, weathering, sedimentation and provenance, as well as the magmatic realm.     

Determination of Gold in e‐Waste Dust Samples and Geological Matrices by ICP‐MS after Extraction by an HClO4‐HBr‐HI‐Aqua Regia Mixture

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.     

Rhenium‐Osmium Isotope Measurements of Geological Reference Material BIR‐1a: Evaluation of Homogeneity and Implications for Method Validation and Quality Control

To evaluate the homogeneity of geological reference material BIR‐1a (basalt; United States Geological Survey, USGS) for Re‐Os isotopic studies at the 0.2–1.0 g test portion size level, sixty‐three precise measurement results of Re and Os mass fractions and isotope amount ratios were obtained over an 18‐month period. These data reveal that the reference material has higher Re (0.691 ± 0.022 ng g^?1, 2s, n = 63) and lower Os mass fractions (0.343 ± 0.089 ng g^?1, 2s, n = 63) than UB‐N (serpentinite, CRPG) and is homogeneous in ¹⁸⁷Os/¹⁸⁸Os isotope amount ratio (0.13371 ± 0.00092, 2s, n = 63) at the 0.2–1.0 g test portion size level. The results are essentially consistent with previous views indicating that BIR‐1a gives precise measurement results for Re‐Os isotope amount ratio measurements at the 1 g test portion size level (Ishikawa et al., Chemical Geology, 2014, 384, 27–46; Meisel and Horan, Reviews in Mineralogy and Geochemistry, 2016, 81, 89–106). Based on these new Re‐Os data and previous studies, we propose BIR‐1a as a useful reference material that can be used in method validation and quality control and interlaboratory comparisons for studies dealing with mafic geological samples at test portion sizes of > 0.4 g.     

δ98/95Mo values and Molybdenum Concentration Data for NIST SRM 610, 612 and 3134: Towards a Common Protocol for Reporting Mo Data

Molybdenum concentration and δ^98/95Mo values for NIST SRM 610 and 612 (solid glass), NIST SRM 3134 (lot 891307; liquid) and IAPSO seawater reference material are presented based on comparative measurements by MC‐ICP‐MS performed in laboratories at the Universities of Bern and Oxford. NIST SRM 3134 and NIST SRM 610 and 612 were found to have identical and homogeneous ⁹⁸Mo/⁹⁵Mo ratios at a test portion mass of 0.02 g. We suggest, therefore, that NIST SRM 3134 should be used as reference for the δ–Mo notation and to employ NIST SRM 610 or 612 as solid silicate secondary measurement standards, in the absence of an isotopically homogeneous solid geological reference material for Mo. The δ^98/95Mo_{JMC Bern} composition (Johnson Matthey ICP standard solution, lot 602332B as reference) of NIST SRM 3134 was 0.25 ± 0.09‰ (2s). Based on five new values, we determined more precisely the mean open ocean δ^98/95Mo_{SRM 3134} value of 2.09 ± 0.07‰, which equals the value of δ^98/95Mo_{JMC Bern} of 2.34 ± 0.07‰. We also refined the Mo concentration data for NIST SRM 610 to 412 ± 9 μg g^?1 (2s) and NIST SRM 612 to 6.4 ± 0.7 μg g^?1 by isotope dilution. We propose these concentration data as new working values, which allow for more accurate in situ Mo determination using laser ablation ICP‐MS or SIMS.     

Introducing a Comprehensive Data Reduction and Uncertainty Propagation Algorithm for U‐Th Geochronometry with Extraction Chromatography and Isotope Dilution MC‐ICP‐MS

We present an open‐source algorithm in Mathematica application (Wolfram Research) with a transparent data reduction and Monte Carlo simulation of systematic and random uncertainties for U‐Th geochronometry by multi‐collector ICP‐MS. Uranium and thorium were quantitatively separated from matrix elements through a single U/TEVA extraction chromatography step. A rigorous calibrator‐sample bracketing routine was adopted using CRM‐112A and IRMM‐035 standard solutions, doped with an IRMM‐3636a ²³³U/²³⁶U ‘double‐spike’ to account for instrumental mass bias and deviations of measured isotope ratios from certified values. The mean of ²³⁴U/²³⁸U and ²³⁰Th/²³²Th in the standard solutions varied within 0.42 and 0.25‰ (permil) of certified ratios, respectively, and were consistent with literature values within uncertainties. Based on multiple dissolutions with lithium metaborate flux fusion, U and Th concentrations in USGS BCR‐2 CRM were updated to 1739 ± 2 and 5987 ± 50 ng g^?1 (95% CI), respectively. The measurement reproducibility of our analytical technique was evaluated by analysing six aliquots of an in‐house reference material, prepared by homogenising a piece of speleothem (CC3A) from Cathedral Cave, Utah, which returned a mean age of 21483 ± 63 years (95% CI, 2.9‰). Replicate analysis of ten samples from CC3A was consistent with ages previously measured at the University of Minnesota by single‐collector ICP‐MS within uncertainties.