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www.rsc.org/jaas Page 1 of 36 Journal of Analytical Atomic Spectrometry
1 2 3 4 5 1 High-precision measurements of tungsten stable isotopes and 6 7 2 application to Earth Sciences 8 3 9 4 Thomas Breton *, Ghylaine Quitté * 10 Manuscript 11 5 Laboratoire de Géologie de Lyon, Ecole normale supérieure de Lyon, Université de Lyon, 12 6 CNRS, UMR 5276, 46 allée d’Italie, F 69364 Lyon cedex, France 13 14 7 * 15 8 Present address: Institut de Recherche en Astrophysique et Planétologie, Observatoire Midi 16 9 Pyrénées, Université de Toulouse, CNRS, UMR 5277, 14 avenue Edouard Belin, F 31400 17 10 Toulouse, France 18 11 19 20 12 Abstract Accepted 21 22 13 Mass dependent isotope fractionation of tungsten (W) isotopes has not received much 23 24 14 attention until recently. This is mainly due to the small fractionation expected – as tungsten 25 26 27 15 has a relatively high atomic mass – combined with the insufficient precision that could be 28 182 182 29 16 achieved with the existing techniques. Tungsten is involved in the Hf W radio 30 31 17 chronometer. Hence, tungsten isotopes are currently mainly used for studying the first stages 32 33 18 of the solar system history, as they are well suited to trace metal silicate equilibration 34 Spectrometry 35 19 processes. At the same time, evaporation, condensation or diffusion are known to fractionate 36 37 38 20 stable isotopes. A better understanding of W stable isotopes behavior during terrestrial and 39 40 21 asteroidal processes will thus potentially shed light on those events. We here present an
41 Atomic 42 22 improved separation procedure based on anion exchange chromatography that allows 43 44 23 achieving quantitative recovery of W. Taking advantage of the last generation multi collector 45 46 47 24 inductively coupled plasma mass spectrometers (MC ICPMS), we also set up a method to 48 49 25 analyze W mass dependent isotope fractionation with an external reproducibility better than 50 51 26 80 ppm and an internal reproducibility of 30 ppm. This new analytical procedure has been Analytical 52 53 27 applied to igneous and iron rich samples, from granites to chondrites and iron meteorites. 54 of 55 28 Isotope variations observed for natural samples are well resolvable and vary from 0.05 to 56 57 58 29 +0.36 per mil per mass unit. 59 60 1 Journal Journal of Analytical Atomic Spectrometry Page 2 of 36
1 2 3 30 1 - Introduction 4 5 31 The study of mass independent fractionation of W isotopes is of great interest for 6 7 1–9 8 32 chronological purposes and for understanding nucleosynthetic processes and subsequent 9 10–12 182 182 10 33 dynamical processes in the solar nebula . The Hf W chronometer is well suited to Manuscript 11 12 34 date, for instance, the formation of iron meteorites 2,6,13–15 , the metamorphism of H 13 14 35 chondrites 16 , or the metal silicate segregation in achondrites 5,7,8,17–19 , thus proving to be useful 15 16 17 36 in understanding the first stages of solar system history and planetary formation. Tungsten 18 19 37 isotope measurements are usually performed after separation of W from the matrix elements 20 Accepted 21 38 using an anion exchange resin, and involve mass spectrometry techniques, be it multi 22 23 39 collector inductively coupled plasma mass spectrometry 1,6,13,15,16 (MC ICMPS) or negative 24 25 ion thermal ionization mass spectrometry 20,21 (N TIMS). 26 40 27 28 41 Stable isotope fractionation provides information about processes, including isotope exchange 29 30 42 between phases, and redox reactions. They allow evaluating diffusion temperatures, 31 32 43 constraining chemical equilibria and kinetics, and characterizing sources of specific material 33 Spectrometry 34 44 and reaction pathways. Fractionation of W stable isotopes is potentially of broad interest in 35 36 37 45 both geochemistry and cosmochemistry. It could for instance bring additional constraints on 38 39 46 the long standing search for the origin of reduced metal in chondrites and primitive 40
41 47 achondrites. It could also provide new information on metal silicate phase equilibrium to help Atomic 42 43 48 unravel the processes involved in the formation of iron meteorites. Additionally, it may clarify 44 45 the processes related to the moon forming impact and the late veneer theories. Tungsten 46 49 47 48 50 stable isotopes may also be used as a tracer of the dissolved minerals in alteration processes, 49 50 51 and its solubility makes W stable isotopes suitable for tracing the geographic origin of detritic 51 Analytical 52 52 material. 53 54 53 Recent improvements in mass spectrometry instrumentation push back the frontiers of mass of 55 56 22–25 26 57 54 dependent fractionations and heavy elements such as cadmium , molybdenum and 58 59 60 2 Journal Page 3 of 36 Journal of Analytical Atomic Spectrometry
1 2 27–30 3 55 thallium have been successfully investigated. Thanks to the stability and sensitivity of the 4 5 56 new generation Thermo Scientific ® Neptune Plus © MC ICPMS and its Jet Cones interface, 6 7 57 the achievable precision on isotope measurements has significantly improved, a pre requisite 8 9
10 58 to study heavy elements presenting only small isotope fractionations. In the following, we Manuscript 11 12 59 present a new method for measuring the fractionation of W stable isotopes with high 13 14 60 precision. 15 16 61 So far, only one study specifically addressed the question of mass dependent fractionation of 17 18 62 W stable isotopes 31 . In the other studies of W isotope fractionation, the mass dependent effect 19 20 Accepted 21 63 is always corrected for during data processing as the measured isotope ratios are internally 22 186 183 23 64 normalized, i.e. corrected for the mass bias using a stable isotope ratio ( W/ W or 24 25 65 186 W/ 184 W) as reference. This normalization erases all mass dependent fractionations, be they 26 27 66 caused by the ICPMS instrument, by the ion exchange procedure, or be they intrinsic to the 28 29 30 67 sample. 31 32 68 33 Spectrometry 34 69 2 - Sample preparation 35 36 37 70 2.1 - Reagents and test-solutions 38 39 71 Samples were prepared in a clean room at the Laboratoire de Géologie de Lyon ENS de 40 © 41 72 Lyon. We used Teflon Savillex vials for every step of the procedure. Commercial HCl, HF Atomic 42 43 73 and HNO 3 acids were distilled once (HCl, HNO 3) or twice (HF) in sub boiling stills. 44 45 Commercial suprapur H O (Merck ©) was also used. Reagent blanks are summarized in Table 46 74 2 2 47 48 75 1. H 2O2 bearing solutions were always prepared in the hour preceding their use to limit the 49 50 76 decomposition of the metastable molecule. Sample handling was performed under a laminar 51 Analytical 52 77 flow in order to reduce the risk of sample contamination. 53 54 78 Our goal was to set up a procedure suitable for most terrestrial and extraterrestrial rock of 55 56 57 79 samples, so that different solutions and natural samples were used throughout our analytical 58 59 60 3 Journal Journal of Analytical Atomic Spectrometry Page 4 of 36
1 2 © 3 80 development: (1) a pure tungsten standard solution (Alfa Aesar for ICPMS) to check the 4 5 81 procedure yield, (2) the NIST SRM 3163 W isotopic standard to ensure there was no 6 7 82 procedure induced isotope fractionation, (3) a home made multi element standard solution as 8 9
10 83 well as (4) W free terrestrial matrices doped with NIST SRM 3163 to check matrix effects, Manuscript 11 12 84 and finally (5) terrestrial and extra terrestrial samples. 13 14 85 A multi element standard solution was prepared from mono element Alfa Aesar © standard 15 16 86 solutions, as a mixture of the most common major and minor elements found in samples of 17 18 87 interest (Na, Mg, Al, K, Ti, Cr, Mn, Fe, Co, Ni, Cu), along with a set of trace elements (Rb, 19 20 Accepted 21 88 Sr, Mo, Sn, Sb, Ba, REE, Hf, Ta, Re, Os, Pb, Th) including the elements interfering with W 22 23 89 (Table 2). Natural matrices were also doped with standard W after removal of the W they 24 25 90 initially contained: the W initially present in rock standards AGV 1, G 2, PCC 1 and W1 was 26 27 91 extracted from 200 mg size samples using the purification method described below and 28 29 30 92 summarized in Table 3, and the eluted matrix was subsequently doped with 500 ng W of 31 32 93 known isotope composition (NIST SRM 3163). This allowed testing the W separation 33 34 94 procedure in natural samples and checking possible matrix effects. Spectrometry 35 36 95 2.2 – Sample preparation and digestion 37 38 96 A variety of terrestrial rock standards have been analyzed in the frame of the present study, 39 40 97 including andesites AGV 1 and AGV 2, basalts BE N and BCR 1, diabase W1, granite G2, 41 Atomic 42 43 98 and peridotite PCC 1. Our new procedure was also applied to extraterrestrial materials: an 44 45 99 ordinary chondrite (Dhajala, H3.8), a carbonaceous chondrite (Allende, CV3), and an iron 46 47 100 meteorite (Gibeon, IVA). 48 49 50 101 Sample surfaces were stripped off using a tungsten free diamond coated stainless steel tool to 51 Analytical 52 102 remove any potential contamination. Samples were then crushed in a corundum mortar and 53 © 54 103 subsequently dissolved in 15 mL Teflon Savillex vials at 120°C on a hotplate during 5 to 10 of 55 56 104 days. Following the procedure developed by Quitté et al. 20 , silicate rich samples were 57 58 59 60 4 Journal Page 5 of 36 Journal of Analytical Atomic Spectrometry
1 2 1 1 1 3 105 digested in a 6 mol.L HCl 27 mol.L HF 16 mol.L HNO 3 mixture (proportions of 4 5 106 2:2:0.1 in volume, with a typical total volume of 10mL for 1 gram of sample). Metal rich 6 7 1 1 1 107 samples were digested in 6 mol.L HCl 27 mol.L HF 16 mol.L HNO 3 (0.1:2:2 in 8 9 20
10 108 volume) after dissolution of the outer part as detailed in Quitté et al. to discard any potential Manuscript 11 12 109 contamination. 13 14 110 After digestion, the samples were evaporated to dryness and taken up twice in 6 mol.L 1 HCl. 15 16 111 If some Ca and Mg fluorides still remained after this step, a few droplets (depending on the 17 18 112 Ca and Mg concentration of the sample 20 ) of a saturated H BO solution were added to ensure 19 3 3 20 Accepted 21 113 a complete dissolution of the fluorides that may scavenge W by co precipitation. 22 23 114 At this stage, a 5 vol.% aliquot was saved for further concentration analyses. As eluents used 24 25 115 for the chromatography include HF, insoluble fluorides must be removed before the ion 26 27 116 exchange procedure to avoid precipitation on the column and plugging of the pores. After 28 29 1 30 117 evaporation of the main fraction, 1 mol.L HF (10mL per gram sample) was added to take up 31 1 32 118 the residue and convert chlorides to fluorides. After drying down, 1 mol.L HF was added a 33 34 119 second time to ensure complete precipitation of fluorides. As we seek a quantitative recovery Spectrometry 35 36 120 of W and as some W (and other HFSE – High Field Strength Elements) co precipitates with 37 38 121 fluorides 32,33 , the latter have to be carefully rinsed with MilliQ H O, then re dissolved in HCl 39 2 40 122 and re precipitated using HF. The procedure has to be repeated several times to get sure that 41 Atomic 42 43 123 no W remains trapped. In detail, the initial sample solution containing the fluorides was 44 45 124 centrifuged (10 minutes at 5000 rpm) and the supernatant, containing most of the W, was 46 47 125 saved. The fluoride precipitate was rinsed with H O and after centrifugation the second 48 2 49 50 126 supernatant was added to the first one and the combined solution evaporated to dryness. The 51 1 Analytical 52 127 residue was then completely dissolved in an excess of 6 mol.L HCl. This solution was 53 1 54 128 evaporated to dryness before taking it up in 1 mol.L HF to precipitate the fluorides again. A of 55 56 129 test performed using 1g of W free Ca Mg fluorides precipitated from a Hawaii basalt and 57 58 59 60 5 Journal Journal of Analytical Atomic Spectrometry Page 6 of 36
1 2 © 3 130 doped with 200 ng of Alfa Aesar W standard showed that the whole procedure has to be 4 5 131 repeated at least twice. Indeed, the W content of fluorides resulting from the processing of the 6 7 132 Hawaii basalt sample after 1 to 3 repetitions of the sequence described above decreased below 8 9
10 133 detection limit after the second iteration (Figure 1). After 2 to 3 cycles of fluoride extraction, Manuscript 11 12 134 the combined supernatants were evaporated to dryness. No Ca and Mg remained in solution 13 14 135 after this step, and all the W has been extracted from the precipitated fluorides. As 100% W is 15 16 136 recovered at this stage, any mass dependent effect on W caused by HFSE capture by CaF 2 17 18 137 and MgF can be ruled out. 19 2 20 Accepted 21 138 22 23 139 3 - Anion-Exchange Chromatography 24 25 The NIST SRM 3163 standard was processed twice using the procedure described by Irisawa 26 140 27 31 28 141 and Hirata . The yield was however 10 to 30% lower than expected and some mass 29 30 142 dependent fractionations were observed, induced by the chemical separation: the processed 31 32 143 standard yielded a non zero and non reproducible isotope composition relative to the 33 Spectrometry 34 144 unprocessed standard. Besides, some W might be lost during sample decomposition due to its 35 36 37 145 co precipitation with the Ca and Mg fluorides, which may affect the W isotope composition. 38 2 39 146 Indeed, the reaction forming WF 6 from WO 4 and the co precipitation of WF 6 with 40
41 147 (Ca,Mg)F 2 may induce isotope fractionation. We therefore set up an alternative method for Atomic 42 43 148 separating and analyzing W stable isotopes in a wide variety of geological samples. This 44 45 method relies on the properties of W in solution, which easily forms complexes with HF and 46 149 47 48 150 H2O2. 49 50 151 The major interferences on W masses during MC ICPMS analysis (Table 2) are Hf and Os 51 Analytical 52 152 (isobaric), Ta and Re (hydrides) and rare earth elements or REE (Ce, Nd, Sm, Eu, Gd, Dy, 53 54 153 Ho, Er, Tm, Yb) which may form complex ions like argides (ArX +), oxides (XO +), dioxides of 55 56 57 58 59 60 6 Journal Page 7 of 36 Journal of Analytical Atomic Spectrometry
1 2 + + + 3 154 (XO 2 ), nitrides (XN ) or fluorides (XF ). Hence all these elements have to be carefully 4 5 155 separated from W fraction during chromatography. 6 7 156 At least 20 ng W are required for a MC ICPMS analysis and some samples are W poor with 8 9
10 157 concentrations down to 10 ppb. In this case, up to 2 g of sample have to be processed, hence Manuscript 11 12 158 large columns were used. The whole procedure may easily be scaled down for smaller 13 14 159 samples, or if a purification step is needed. 15 16 160 After sample digestion and fluoride extraction, 10 mL of 1 mol.L 1 HF were added to the 17 18 161 residue and heated at 100°C on a hotplate overnight. The solution was then diluted by adding 19 20 Accepted 21 162 6 mL of H 2O and 0.6 mL of 10% H 2O2, and loaded onto a column filled with 10mL Bio Rad 22 23 163 AG1 X8 anionic resin (200 400 mesh, chloride form) previously cleaned and equilibrated 24 25 164 with 2 mol.L 1 HF 4 mol.L 1 HCl. The elution procedure is adapted from the procedure by 26 27 165 Quitté et al. 20 and is summarized in Table 3. Many matrix elements are not retained on the 28 29 30 166 resin and start eluting immediately. The remaining matrix as well as REE are then washed out 31 1 1 32 167 with 70 mL 1 mol.L HCl 2% H 2O2. Tungsten is finally recovered in 60 mL 4 mol.L 33 1 1 1 Spectrometry 34 168 HNO 3 0.5 mol.L HF. This mixture was preferred to 4 mol.L HCl 2 mol.L HF to ensure 35 36 169 the complete elution of W in the smallest possible volume. The analysis of the W cut revealed 37 38 170 that only minor amounts of Mo were present, together with traces of Cd, Cr and Zn. No or 39 40 171 minor traces of Os were found in the W fraction at this stage. Indeeed, a long (36 72h) and 41 Atomic 42 43 172 low T evaporation of the recovered W fraction enabled to ensure the volatilization of this 44 45 173 element. Mo/W ratios were always lower than 10 3, so that the effect of Mo 2+ on masses 184 46 47 174 and 186 was negligible, as demonstrated by Qin et al. 12 . REE, Ta, Hf and Re were completely 48 49 50 175 absent from the W cut. The yield of our new procedure is 99.8 ± 1.2 % for W, with typical 51 Analytical 52 176 blanks of 50 100 pg W. 53
54 177 of 55 56 178 4 - Mass spectrometry 57 58 59 60 7 Journal Journal of Analytical Atomic Spectrometry Page 8 of 36
1 2 3 179 4.1 – Protocol 4 5 180 Isotope measurements have been performed at LGL TPE, ENS de Lyon, using a Thermo 6 7 181 Scientific © Neptune Plus instrument equipped with a Jet sampler cone and a X skimmer cone, 8 9 34
10 182 which reduce odd/even isotope separation, improve sensitivity and reduce mass bias . The Manuscript 11 12 183 instrument was connected to a Cetac Aridus desolvating system. Its sensitivity represents an 13 14 184 asset for the study of W stable isotopes, as it limits the amount of rare material like meteorites 15 16 185 required for one analysis while enabling a high precision determination of isotope ratios. 17 18 186 In order to ensure the stability of W in the analyzed solution, residues obtained after 19 20 Accepted 21 187 chromatography were taken up in a HNO 3 solution containing traces of HF (typically 0.05N). 22 23 188 A run consisted of 2 blocks of 30 to 40 measurements. The typical sensitivity was 300 400 24 25 189 volts/ppm (amplifier resistor: 10 11 ohm). Samples were analyzed 2 to 5 times at a 26 27 190 concentration of 10 to 20 ppb using the standard sample bracketing technique. As noticed by 28 29 35 30 191 Qin et al. , a difference in relative concentrations between the standard and the sample may 31 32 192 induce artifacts on the W isotope measurements. In the present study, W concentrations of the 33 34 193 samples were adjusted within 5 % to the standard concentration, ensuring the artifact Spectrometry 35 36 194 fractionation – if any – remained lower than 0.01 ‰. 37 38 195 The mass dispersion of the Neptune Plus MC ICPMS permits to measure simultaneously the 39 40 196 four major isotopes of tungsten (182, 183, 184, 186), two isotopes of the internal standard Hf 41 Atomic 42 43 197 (178, 179 see next paragraph), as well as one isotope of Os (188) to correct the potential 44 45 198 isobaric interferences on masses 184 and 186. The abundances of 184 Os and 186 Os are inferred 46 47 199 using the canonical ratios: 184 Os/ 188 Os = 0.00149 and 186 Os/ 188 Os = 0.11975 36 . The cup 48 49 50 200 configuration is given in Table 4. 51 Analytical 52 201 4.2 – Correction of the instrumental mass bias 53
54 202 The W isotope composition measured in meteorites results from several distinct contributions: of 55 56 203 the abundance of radiogenic 182 W (decay product of 182 Hf) is a function of the age of the 57 58 59 60 8 Journal Page 9 of 36 Journal of Analytical Atomic Spectrometry
1 2 3 204 sample, while nucleosynthetic and cosmogenic effects also modify the W isotope ratios in a 4 5 205 mass independent way 4,15,37,38 . Superimposed to these isotope anomalies are the mass 6 7 206 dependent fractionations of W stable isotopes. Our new protocol was developed with the aim 8 9
10 207 of studying at the same time stable isotope fractionation, nucleosynthetic anomalies and Manuscript 11 182 182 12 208 radioactive decay of Hf (via the determination of W abundance). The goal was therefore 13 14 209 to get accurate determination of both stable isotope fractionation and mass independent 15 16 210 anomalies. In this context, the use of a double spike was excluded, and the instrumental mass 17 18 211 bias was corrected for using an internal standard. Two elements were potential candidates: 19 Accepted 20 31 21 212 hafnium (Hf), and rhenium (Re) already used by Irisawa and Hirata . Two series of a NIST 22 23 213 SRM 3163 standard solution doped with either Hf or Re were measured on the same day in 24 25 214 the frame of the present work to compare both approaches. The measurements performed 26 27 215 using Hf as an internal standard display an external reproducibility of 0.04‰ for the 28 29 183 184 30 216 W/ W isotope ratio whereas those with Re doping have a reproducibility of 0.09‰ 31 32 217 (Figure 2A). The Hf doping was therefore selected, using a 1000 ppm Hf Alfa Aesar standard 33 34 218 solution. The 180 W isotope cannot be measured due to the Hf isobaric interference: a precise Spectrometry 35 36 219 interference correction is not achievable because of the relative abundances of both elements 37 38 220 (Hf and W) on mass 180. 180 W is indeed the least abundant W isotope (0.13%) whereas the 39 40 221 abundance of 180 Hf is 35.1 %. It is of note that the Hf doping avoids the contribution of Re 41 Atomic 42 43 222 hydride on mass 186. 44 45 223 The instrument generally induces a time dependent mass bias ascribed to instabilities in the 46 47 224 nebulization chamber, matrix effects, and small variations of the gas flow conditions in the 48 49 50 225 Aridus. Long term variations of the instrumental mass bias were corrected for using the 51 Analytical 52 226 standard sample bracketing technique (measurements of a standard solution are interspersed 53
54 227 with analyses of samples), and run to run variations with Hf doping. The mass bias βHf is of 55 56 228 estimated using the 178 Hf/ 179 Hf ratio: 57 58 59 60 9 Journal Journal of Analytical Atomic Spectrometry Page 10 of 36
1 2 3 4 5 6 ln 7 8 9 = 177.94371 10 ln Manuscript 11 178.94583 36 12 229 where . 13 = 2.00287 14 15 230 The W isotope ratios are then corrected using a mass fractionation exponential law: 16 17 18 19 = Accepted 20 21 i j 22 231 where W and W are two distinct W isotopes of respective masses i and j. 23 24 232 The amount of Hf added for doping is adjusted so as both standards and samples finally have 25 26 233 the same Hf concentration. The accuracy and precision of the measurements were similar for 27 28 234 Hf/W ratios of 0.5 to 1, as long as the Hf concentration enabled the Hf isotope composition to 29 30 31 235 be measured with enough accuracy. As we aimed at analyzing small quantities of material 32 33 236 including W poor meteorites, standards and samples were measured at low W concentration. 34 Spectrometry 35 237 Consequently, Hf was added to achieve a Hf/W ratio of 1 to improve the precision of the 36 37 238 correction. 38 39 239 Once corrected for the instrumental mass bias, W isotope ratios are expressed relative to the 40
41 Atomic 42 240 NIST SRM 3163 standard. As the ε notation is commonly used for the mass independent 43 44 241 fractionation of tungsten isotopes, and contrarily to what has been proposed by Irisawa and 45 46 242 Hirata 31 , we suggest to use the common δ notation (per mil variations) to report mass 47 48 243 dependent fractionations of W stable isotopes, even if the observed variations are often below 49 50 51 244 1 δ: Analytical 52 53 54 of 55 56 ( / ) = 1000. − 1 57 58 59 60 10 Journal Page 11 of 36 Journal of Analytical Atomic Spectrometry
1 2 3 4 245 is the mass bias corrected isotope ratio of the sample and is the average 5 6 246 value of the two bracketing standards. Analytical errors on the bracketing standards are not 7 8 9 247 propagated into the δ value of the samples.
10 Manuscript 11 248 12 13 249 5 - Results and discussion 14 15 16 250 5.1. Isotope fractionation on the ion exchange resin and matrix effects 17 18 251 Figure 3 presents the elution curve and the total amount of W recovered (Figure 3A), along 19 20 252 with the isotope composition of each 10 mL subfraction (Figure 3B). This graph allows Accepted 21 22 253 recalculating the isotope composition of the recovered W fraction for yields lower than 100 % 23 24 25 254 (Figure 3C). The NIST SRM 3163 standard fractionates on the column, the light isotopes 26 27 255 going faster than the heavy ones. If only 80% of the total W is recovered, the procedure 28 29 256 induces a systematic isotope fractionation of ≈0.05‰, comparable to the precision achieved 30 31 257 on isotope measurements. A quantitative recovery of W is therefore required for studying 32 33 34 258 stable isotope fractionation, which is the case of the chromatography procedure described Spectrometry 35 36 259 above. The NIST SRM 3163 W standard solution processed through our protocol shows no 37 38 260 evidence of procedure induced isotope fractionation within error, as expected from a 39 40 261 quantitative yield (Figure 4).
41 Atomic 42 262 Matrix effects were checked by doping natural matrices with W standard after removing the 43 44 45 263 naturally occurring W of the sample. The sample doped with the standard was processed 46 47 264 again through the full chemical separation procedure and analyzed. Results for doped matrices 48 49 265 are presented in Figure 4. All samples display the same isotope composition as the NIST 50 51 266 SRM 3163 W standard within uncertainty, with a typical standard deviation (2SD, n = 3 4) Analytical 52 53 267 better than 0.05 δ.amu 1, except for sample AGV 1 NIST that presents a larger error bar. 54 of 55 56 268 Hence, our procedure does not induce any isotope fractionation related to matrix effects. 57 58 59 60 11 Journal Journal of Analytical Atomic Spectrometry Page 12 of 36
1 2 3 269 Additionally, the use of a Jet X cones interface has previously been reported as generating 4 5 270 unpredictable effects such as mass independent fractionation of 180 W 39 . In the present study, 6 7 271 we did not observe any noticeable effect for the mass dependent fractionation of W stable 8 9
10 272 isotopes. Manuscript 11 12 273 5.2. Reproducibility of the measurements 13 14 274 The external reproducibility (2SD) achieved for 20 30 replicates of W standard NIST SRM 15 16 275 3163 measured over a day at a concentration of 20 ppb (and interspersed with samples) is 17 18 276 better than 0.09 δ or 90 ppm per amu for 182 W/ 184 W, 0.07 δ or 70 ppm per amu for 183 W/ 184 W, 19 Accepted 20 186 184 21 277 and 0.17 δ or 170 ppm per amu for W/ W. The typical internal reproducibility for one 22 23 278 measurement (2SD), be it for the standard or a sample, is 60 ppm, 50 ppm, and 140 ppm per 24 25 279 amu for 182 W/ 184 W, 183 W/ 184 W, and 186 W/ 184 W respectively. Figure 2B shows a long term 26 27 280 reproducibility (2SD) of 80ppm for the 183 W/ 184 W ratio obtained for the standard over several 28 29 30 281 sessions (2 months period), comparable to the one day reproducibility. 31 183 32 282 5.3 – The case of W 33 34 283 Recently, mass independent anomalies were reported on 183 W for standards processed through Spectrometry 35 36 284 a tungsten separation procedure 15 . According to the authors, these anomalies are related to a 37 38 285 mass independent fractionation between odd and even isotopes during sample preparation, W 39 40 286 purification or re dissolution of the purified W fraction. In the present piece of work, matrices 41 Atomic 42 43 287 doped with the NIST SRM 3163 W standard do not present either mass dependent 44 45 288 fractionation or any mass independent effect. The anomalies observed in previous studies are 46 47 289 potentially explained by the formation of small amounts of hydrides in the plasma during 48 49 50 290 analysis. For the generation of a proportion p of W hydrides, we modeled the measured 51 Analytical 52 291 abundance on each mass with the following approximation: 53
54 of 55 = (1 − ) + 56 57 58 59 60 12 Journal Page 13 of 36 Journal of Analytical Atomic Spectrometry
1 2 3 292 Here, represents the measured abundance on mass 18i (i=0, 2, 3, 4 or 6) and is defined 4 5 293 as follows: . and correspond 6 = − + 7 8 294 to the theoretical abundance of each isotope when it exists (else 0). 9 186 183 10 295 After internal normalization to W/ W= 1.985935, we calculated the deviation relative to a Manuscript 11 12 296 standard unaffected by hydride generation. This deviation is expressed in unit: 13 14 15 16 17 18 ( / ) = 10 000. − 1 19 20 Accepted 21 297 The line in Figure 5 represents the effect of a difference between standards and samples in 22 23 + + 24 298 terms of the proportion of W hydrides generated. An increase of 10ppm in the WH /W ratio 25 182 184 183 184 26 299 induces a shift of 0.171 ε of the W/ W ratio and of +0.076 ε of the W/ W ratio. 27 28 300 The W isotope data for NIST SRM 129c from Kruijer et al. 15 plot along the calculated line for 29 30 301 hydrides generation. Thus, a small difference of 10 15 ppm of hydrides between standards 31 32 302 and samples can be responsible for the observed mass independent anomalies (Figure 5). This 33 Spectrometry 34 15 35 303 could be an alternative explanation to the one proposed by Kruijer et al. who pointed out 36 37 304 problems of W loss during re dissolution of the samples in Savillex beakers. 38 39 305 5.4 – Comparison with literature data 40
41 306 In the following, data are presented as variations of the isotopic composition per mass unit Atomic 42
43 1 44 307 (amu ): 45 / 46 47 ( ) ( ) 48 = − 184 49 31,40 50 308 Tungsten stable isotopes data are scarce in the literature. Irisawa analyzed some terrestrial 51 Analytical 52 309 and meteoritic materials, among them the Gibeon IVA iron meteorite. To compare with our 53
54 310 data set, we recalculated 2SD uncertainties from this previous study as Irisawa reported of 55 56 311 analytical errors as SE. Our data for Gibeon agree within uncertainty with those of Irisawa 57 58 59 60 13 Journal Journal of Analytical Atomic Spectrometry Page 14 of 36
1 2 3 312 (Figure 6), even if a small enrichment in heavy isotopes is now resolvable from the standard 4 5 313 value. The small apparent shift between the average value for Gibeon in both sets of data 6 7 314 might be due to an incomplete recovery of the tungsten fraction in the previous study, as 8 9
10 315 presented in Figure 3: if the elution tail is not fully recovered, the measured isotope signature Manuscript 11 12 316 is indeed too light. 13 14 317 5.5 – Natural samples 15 16 318 Terrestrial volcanic and ultrabasic rock standards (AGV 1, AGV 2, BCR 1, BE N, G2, PCC 17 18 319 1 and W1) as well as extraterrestrial materials (Allende, Dhajala and Gibeon meteorites) have 19 20 Accepted 21 320 been analyzed. Results are presented in Table 5. On Figure 7A, data for terrestrial samples 22 23 321 plot on mass dependent isotope fractionation lines, but this is not the case for extraterrestrial 24 25 322 samples (Figure 7B). For the latter, the abundance of radiogenic 182 W depends on the 26 27 323 radioactive decay of 182 Hf, hence the δ182 W/ 184 W may be lower or higher than expected for a 28 29 30 324 pure mass dependent fractionation. Besides, nucleosynthetic anomalies in meteorites may also 31 183 184 186 184 32 325 modify the isotope pattern for δ W/ W and δ W/ W. Such anomalies have not been 33 34 326 corrected here, and may explain that the fractionation patterns do not intercept the x axis at Spectrometry 35 36 327 mass 183 in figure 7B. Small uncorrected nucleosynthetic anomalies may also explain that 37 38 328 uncertainties (2SD) calculated for extraterrestrial samples are somewhat higher than for 39 40 329 terrestrial samples. In a δ183 W/ 184 W vs. δ186 W/ 184 W diagram (i.e. without considering 182 W), 41 Atomic 42 43 330 all natural samples – including meteorites – plot on a mass dependent fractionation line 44 45 331 (Figure 8). As shown on Figure 9, replicate measurements perfectly agree with each other. 46 47 332 This figure also demonstrates that some W isotope variability exists between natural samples: 48 49 50 333 the mass dependent fractionations observed in the terrestrial samples vary from 0.05 to +0.37 51 1 1 Analytical 52 334 δ.amu . Peridotites present the lightest signature in average ( 0.05 ± 0.10 δ.amu ); the 53
54 335 basaltic samples (BE N, BCR 1, W1) all show a very homogeneous signature ranging from of 55 56 336 +0.09 to +0.14 δ.amu 1 (average: +0.11 ± 0.06 δ.amu 1). Andesitic rocks AGV 1 and AGV 2 57 58 59 60 14 Journal Page 15 of 36 Journal of Analytical Atomic Spectrometry
1 2 1 3 337 display the heaviest signatures (+0.23 and +0.36 δ.amu ) while granite G2 presents a lighter 4 5 338 signature ( 0.02 ± 0.06 δ.amu 1) undistinguishable from the NIST SRM 3163 standard. This 6 7 339 isotope variability opens a new field of investigations and confirms the potential of W stable 8 9
10 340 isotope fractionation to trace and apprehend geological processes. Manuscript 11 12 341 13 14 342 Conclusions 15 16 17 343 A new method has been set up to analyze W stable isotopes. This protocol, based on a one 18 19 344 step anion exchange chromatography, is suitable for a large variety of geological matrices. 20 Accepted 21 345 The procedure yield is 99.8 ± 1.2 %. The NIST SRM 3163 standard solution (with or without 22 23 346 a rock matrix) processed through the ion exchange resin showed no mass dependent isotope 24 25 fractionation within error. Hafnium, more specifically the 178 Hf/ 179 Hf ratio, was used as an 26 347 27 185 187 28 348 internal standard to correct the instrumental mass bias. Alternatively, the Re/ Re ratio 29 30 349 may also be used even if the uncertainties on the normalized values are then slightly larger. 31 32 350 Tungsten stable isotope measurements performed with the last generation Neptune Plus MC 33 Spectrometry 34 351 ICPMS equipped with Jet cones are 10 to 20 times more sensitive than those reported in 35 36 37 352 previous studies with other instruments. 38 39 353 Our new method was applied to terrestrial and extraterrestrial samples: they present various 40
41 354 and distinct stable isotope signatures. Even if the measured W mass dependent isotope Atomic 42 43 355 fractionation is in most cases <0.5 δ.amu 1, the variations are clearly resolvable from the 44 45 standard value within uncertainties. Thus, the present piece of work confirms the potential of 46 356 47 48 357 W stable isotopes to trace geological processes. 49 50 358 Acknowledgements 51 Analytical 52 53 359 We are grateful to P. Télouk for maintaining the ICPMS instruments running well. We also
54 of 55 360 acknowledge the MNHN (Paris) for providing meteorite samples. Last but not least, we thank 56 57 58 59 60 15 Journal Journal of Analytical Atomic Spectrometry Page 16 of 36
1 2 3 361 the two anonymous reviewers for their advices and comments that helped improving the 4 5 362 manuscript. 6 7 363 This work was supported by the French National Program of Planetology (PNP). 8 9
10 364 References Manuscript 11 12 13 365 1. C. Burkhardt, T. Kleine, B. Bourdon, H. Palme, J. Zipfel, J. M. Friedrich, and D. S. 14 366 Ebel, Geochim. Cosmochim. Acta , 2008, 72 , 6177–6197. 15 16 17 367 2. T. Kleine, K. Mezger, H. Palme, E. Scherer, and C. Münker, Geochim. Cosmochim. 18 368 Acta , 2005, 69 , 5805–5818. 19 20 369 3. A. Markowski, Ph.D. thesis, ETH Zürich, 2006. Accepted 21 22 370 4. A. Markowski, I. Leya, G. Quitté, K. Ammon, A. N. Halliday, and R. Wieler, Earth 23 371 Planet. Sci. Lett. , 2006, 250 , 104–115. 24 25 26 372 5. A. Markowski, G. Quitté, T. Kleine, A. Halliday, M. Bizzarro, and A. Irving, Earth 27 373 Planet. Sci. Lett. , 2007, 262 , 214–229. 28 29 374 6. A. Markowski, G. Quitté, A. Halliday, and T. Kleine, Earth Planet. Sci. Lett. , 2006, 30 375 242 , 1–15. 31 32 376 7. G. Quitté and J. L. Birck, Earth Planet. Sci. Lett. , 2004, 219 , 201–207. 33 34 Spectrometry 35 377 8. T. Schulz, C. Münker, K. Mezger, and H. Palme, Geochim. Cosmochim. Acta , 2010, 36 378 74 , 1706–1718. 37 38 379 9. T. Schulz, C. Münker, H. Palme, and K. Mezger, Earth Planet. Sci. Lett. , 2009, 280 , 39 380 185–193. 40
41 381 10. C. Burkhardt, T. Kleine, N. Dauphas, and R. Wieler, Astrophys. J. , 2012, 753 , L6. Atomic 42 43 382 11. K. Irisawa, Q. Z. Yin, and T. Hirata, Geochem. J. , 2009, 43 , 395–402. 44 45 46 383 12. L. Qin, N. Dauphas, M. Wadhwa, A. Markowski, R. Gallino, P. E. Janney, and C. 47 384 Bouman, Astrophys. J. , 2008, 674 , 1234–1241. 48 49 385 13. L. Qin, N. Dauphas, M. Wadhwa, J. Masarik, and P. E. Janney, Earth Planet. Sci. Lett. , 50 386 2008, 273 , 94–104. 51 Analytical 52 387 14. A. Scherstén, T. Elliott, C. Hawkesworth, S. Russell, and J. Masarik, Earth Planet. Sci. 53 388 Lett. , 2006, 241 , 530–542. 54 of 55 56 389 15. T. S. Kruijer, P. Sprung, T. Kleine, I. Leya, C. Burkhardt, and R. Wieler, Geochim. 57 390 Cosmochim. Acta , 2012, 99 , 287–304. 58 59 60 16 Journal Page 17 of 36 Journal of Analytical Atomic Spectrometry
1 2 3 391 16. T. Kleine, M. Touboul, J. A. Van Orman, B. Bourdon, C. Maden, K. Mezger, and A. N. 4 392 Halliday, Earth Planet. Sci. Lett. , 2008, 270 , 106–118. 5 6 393 17. G. Quitté, J. Birck, and C. J. Allègre, Earth Planet. Sci. Lett. , 2000, 184 , 83–94. 7 8 394 18. D. C. Lee, A. N. Halliday, S. J. Singletary, and T. L. Grove, Earth Planet. Sci. Lett. , 9
10 395 2009, 288 , 611–618. Manuscript 11 12 396 19. M. Touboul, T. Kleine, B. Bourdon, J. A. Van Orman, C. Maden, and J. Zipfel, Earth 13 397 Planet. Sci. Lett. , 2009, 284 , 168–178. 14 15 398 20. G. Quitté, J. L. Birck, F. Capmas, and C. J. Allègre, Geostand. Geoanalytical Res. , 16 399 2002, 26 , 149–160. 17 18 19 400 21. M. Touboul and R. J. Walker, Int. J. Mass Spectrom. , 2011, 309 , 109–117. 20 Accepted 21 401 22. W. Abouchami, S. J. G. Galer, T. J. Horner, M. Rehkämper, F. Wombacher, Z. Xue, 22 402 M. Lambelet, M. Gault Ringold, C. H. Stirling, M. Schönbächler, A. E. Shiel, D. Weis, 23 403 and P. F. Holdship, Geostand. Geoanalytical Res. , 2013, 37 , 5–17. 24 25 404 23. F. Wombacher, M. Rehkämper, K. Mezger, C. Münker, and A. Bischoff, Goldschmidt 26 405 Conf. Abstr. , 2002. 27 28 29 406 24. F. Wombacher, M. Rehkämper, K. Mezger, A. Bischoff, and C. Münker, Geochim. 30 407 Cosmochim. Acta , 2008, 72 , 646–667. 31 32 408 25. F. Wombacher, M. Rehkämper, K. Mezger, and C. Münker, Geochim. Cosmochim. 33 409 Acta , 2003, 67 , 4639–4654. 34 Spectrometry 35 410 26. C. Burkhardt, R. C. Hin, T. Kleine, and B. Bourdon, Earth Planet. Sci. Lett. , 2014, 391 , 36 411 201–211. 37 38 39 412 27. S. G. Nielsen, M. Rehkämper, D. Porcelli, P. Andersson, A. N. Halliday, P. W. 40 413 Swarzenski, C. Latkoczy, and D. Günther, Geochim. Cosmochim. Acta , 2005, 69 ,
41 414 2007–2019. Atomic 42 43 415 28. S. G. Nielsen, M. Goff, S. P. Hesselbo, H. C. Jenkyns, D. E. LaRowe, and C. T. A. 44 416 Lee, Geochim. Cosmochim. Acta , 2011, 75 , 6690–6704. 45 46 417 29. S. G. Nielsen, L. E. Wasylenki, M. Rehkämper, C. L. Peacock, Z. Xue, and E. M. 47 48 418 Moon, Geochim. Cosmochim. Acta , 2013, 117 , 252–265. 49 50 419 30. M. Rehkämper, M. Frank, J. R. Hein, D. Porcelli, A. Halliday, J. Ingri, and V. 51 420 Liebetrau, Earth Planet. Sci. Lett. , 2002, 197 , 65–81. Analytical 52 53 421 31. K. Irisawa and T. Hirata, J. Anal. At. Spectrom. , 2006, 21 , 1387. 54 of 55 422 32. A. Makishima and E. Nakamura, Geostand. Geoanalytical Res. , 1999, 23 , 137–148. 56 57 58 59 60 17 Journal Journal of Analytical Atomic Spectrometry Page 18 of 36
1 2 3 423 33. R. Tanaka, A. Makishima, H. Kitagawa, and E. Nakamura, J. Anal. At. Spectrom. , 4 424 2003, 18 , 1458. 5 6 425 34. N. Shirai and M. Humayun, J. Anal. At. Spectrom. , 2011, 26 , 1414. 7 8 426 35. L. Qin, N. Dauphas, P. E. Janney, and M. Wadhwa, Anal. Chem. , 2007, 79 , 3148–54. 9
10 Manuscript 11 427 36. K. J. R. Rosman and P. D. P. Taylor, Pure Appl. Chem. , 1998, 70 , 217–235. 12 13 428 37. I. Leya, H. Lange, S. Neumann, R. Wieler, and R. Michel, Meteorit. Planet. Sci. , 2000, 14 429 35 , 259–286. 15 16 430 38. N. Wittig, M. Humayun, A. D. Brandon, S. Huang, and I. Leya, Earth Planet. Sci. 17 431 Lett. , 2013, 361 , 152–161. 18 19 20 432 39. T. Schulz, C. Münker, and S. T. M. Peters, Earth Planet. Sci. Lett. , 2013, 362 , 246– Accepted 21 433 257. 22 23 434 40. K. Irisawa, Ph.D. thesis, Tokyo Institute of Technology, 2007. 24 25 435 26 27 436 28 29 30 437 Tables and Figures 31 32 33 438 Table 1: Blank values for the concentrated reagents used in this study. H 2O2: Merck Suprapur 34 Spectrometry 35 439 commercial reagent; mineral acids: * distilled; ** bi distilled. 36 37 38 39 440 Table 2: Isobars and main molecular interferences on W isotopes. 40
41 Atomic 42 441 Table 3: Elution scheme for the quantitative recovery of W. The column is filled with 10 mL 43 44 442 Biorad AG1 X8 (200 400 mesh) anion exchange resin in chloride form. 45 46 47 48 443 Table 4: Cup configuration on the Neptune Plus MC ICPMS for the analysis of W stable 49
50 444 isotopes and correction of Os isobaric interferences. Hf was used as an internal standard to 51 Analytical 52 445 correct the instrumental mass bias (see text). 53
54 of 55 446 Table 5: W stable isotope data for terrestrial reference materials and meteorites. Results are 56 57 178 179 58 447 internally normalized to Hf/ Hf = 2.00287 (Rosman and Taylor, 1998). AGV 1 and 59 60 18 Journal Page 19 of 36 Journal of Analytical Atomic Spectrometry
1 2 3 448 AGV 2: andesite; G2: granite; PCC 1: peridotite; W1: diabase; BCR1 and BE N: basalts. The 4 5 449 column on the right displays the weighted mean of the measured δ.amu 1 relevant to the 6 7 450 sample (i.e. we did not take the 182 W/ 184 W ratio into account for meteorite samples). 2SD of 8 9
10 451 individual samples refer to two internal analytical errors; 2SD of the mean was calculated as Manuscript 11 12 452 the deviation about the mean. The error associated to the mean value of a population is 13 14 453 calculated as 2SE. 15 16 17 454 Figure 1: Proportion of tungsten that remains trapped in the fluorides after each dissolution 18 19 20 455 precipitation and washing step. 200 ng of W and 1g of (Ca,Mg) fluorides were used for these Accepted 21 22 456 tests. 23 24 25 457 Figure 2: A Comparison of the mean values and reproducibility of the standard, using Re 26 27 458 doping or Hf doping to correct the instrumental mass bias. Grey fields correspond to two 28 29 30 459 standard deviations (2SD) calculated on the measured values. Different standard solutions 31 32 460 have been tested, as well as different procedures: (a 1) 20 ppb W + 20 ppb Re; (a 2) 20 ppb W + 33 Spectrometry 34 461 20 ppb Re + sample bracketing; (b 1) 20 ppb W + 20 ppb Hf; (b 2) 20 ppb W + 20 ppb Hf + 35 36 462 sample bracketing; (c 1) 10 ppb W + 10 ppb Hf; (c 2) 10 ppb W + 10 ppb Hf + sample 37 38 463 bracketing. B Long term variability (April to June 2013) of the standard mass dependent 39 40 464 fractionation. The standards were interspersed with samples, which are not reported here. 41 Atomic 42 43 465 Error bars are within run statistics (2SD) on the raw ratios. 44 45 46 466 Figure 3: Fractionation of W isotopes during ion exchange. A – Fraction of W eluted as a 47 48 49 467 function of the volume, both in the successive 10mL elution fractions (dashed line) and total 50 51 468 fraction of eluted W (grey line). B – deviation of W stable isotope signature in each fraction Analytical 52 53 469 relative to the unprocessed standard. C – deviation of the W stable isotope signature in the
54 of 55 470 cumulative W fraction. 56 57 58 59 60 19 Journal Journal of Analytical Atomic Spectrometry Page 20 of 36
1 2 3 471 Figure 4: Check for matrix effects on W isotope fractionation (per mass unit) during the 4 5 472 purification stage through anion exchange resin AG1 X8 (200 400 mesh). In this diagram, 6 7 473 AGV 1, PCC 1, G2 and W1 represent the rock matrices extracted from the corresponding 8 9
10 474 rock standards, respectively andesite, peridotite, granite and diabase. After complete Manuscript 11 12 475 extraction of their natural W, the geological standard rock matrices were doped with 500 ng 13 14 476 of NIST SRM 3163 W. * denotes the pure (i.e. without rock matrix) NIST SRM 3163 15 16 477 standard processed through the chromatography procedure as a sample. n represents the 17 18 478 number of MC ICPMS replicate measurements. In this diagram, the reported δ iW/ M is the 19 Accepted 20 182 184 183 184 186 184 21 479 average of the measured δ( W/ W), δ( W/ W) and δ( W/ W) values divided by their 22 182 184 23 480 respective mass differences (e.g. δ( W/ W)/2). Error bars correspond to 2SD uncertainties. 24 25 481 All samples yield the same isotope composition as the pure standard solution, confirming the 26 27 482 absence of any matrix effect. 28 29 30 31 483 Figure 5: Effects of the variability in hydrides formation between standards and samples 32 33 484 during W mass spectrometry analysis (black line) compared to the data obtained by (Kruijer 34 Spectrometry 35 485 et al., 2012), and internally normalized to 186 W/ 183 W= 1.985935 (noted 6/3). In this diagram, 36 37 486 we model the formation of hydrides on a NIST SRM 3163 standard as follows: we supposed a 38 39 40 487 hydride generation on each isotope proportionally to the abundance of the isotope. The length
41 Atomic 42 488 of the black arrow represents a 10 ppm hydride generation difference between sample and 43 44 489 standard. See text for calculation details. 45 46 47 490 Figure 6: Comparison of the measured δ 184 W/ 183 W for Gibeon (IVA iron meteorite) with data 48 49 50 491 from the literature. Black dots are values from Irisawa (2007) in which 2SD errors were 51 Analytical 52 492 recalculated from the reported SE errors. Open squares are values obtained in the present 53
54 493 study. Error bars are within run statistics (2SD) on the raw ratios. of 55 56 57 58 59 60 20 Journal Page 21 of 36 Journal of Analytical Atomic Spectrometry
1 2 18X 3 494 Figure 7: Measured δ W (X=2, 3, or 6) reported as a function of the mass. For clarity, error 4 5 495 bars were not reported on this figure but can be found in Table 5. A – Data for terrestrial 6 7 496 samples (rock standards: andesite (AGV 1, AGV 2), basalt (BCR 1, BE N), diabase (W1), 8 9
10 497 granite (G 2) and peridotite (PCC 1)). B – Data for meteorite samples (ordinary chondrite: Manuscript 11 12 498 Dhajala (H3.8); carbonaceous chondrite: Allende (CV3); and iron meteorite: Gibeon (IVA)). 13 14 15 499 Figure 8: Mass dependent fractionation of W isotopes in mafic and ultramafic rock samples. 16 17 500 In a three isotopes diagram, the samples fall on the theoretical mass dependent fractionation 18 19 20 501 line (grey line). Symbols correspond to the weighted average and the propagated error (2SD). Accepted 21 22 502 Symbols are the same as on Figure 7. 23 24 25 503 Figure 9: Mean values of the mass dependent fractionation of W isotopes in terrestrial and 26 27 504 extraterrestrial samples. Each sample has been measured 2 to 6 times. Replicates for Gibeon 28 29 184 183 30 505 are presented in figure 6 (δ W/ W). Reported error bars correspond to two standard 31 1 32 506 deviations from the mean value (δ.amu ) for each measured sample. Larger symbols 33 34 507 represent the mean of the measurements for each rock and their error bars correspond to 2SE Spectrometry 35 36 508 (two standard errors) about the mean value δ.amu 1 for all the measured samples of the rock. 37 38 39 40
41 Atomic 42 43 44 45 46 47 48 49 50 51 Analytical 52 53
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1 2 3 1 A new method for high precision measurements of W 4 2 stable isotopes by MC-ICPMS enables to discriminate 5 3 small mass-dependent fractionations, with applications 6 4 in numerous fields of earth, planetary and 7 5 environmental sciences. 8 9 6 10 Manuscript 11 12 13 14 15 16 17 18 19 20 Accepted 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Spectrometry 35 36 37 38 39 40
41 Atomic 42 43 44 45 46 47 48 49 50 51 Analytical 52 53
54 of 55 56 57 58 59 60 1 Journal Page 23 of 36 Journal of Analytical Atomic Spectrometry
1 Isotope 2 180 W (0.12 %) 182 W (26.50 %) 183 W (14.31 %) 184 W (30.64 %) 186 W (28.43%) 3 (abundance) Interferences: 4 Isobaric 180 Hf 5 184 Os 186 Os 180 Ta 6 Argides 40 Ar 144 Nd + 40 Ar 142 Ce + 40 Ar 146 Nd + 7 40 Ar 143 Nd + 40 Ar 144 Sm + Not measured 40 Ar 142 Nd + 36 Ar 150 Nd + 8 36 Ar 147 Nd + 36 Ar 148 Nd + 36 Ar 146 Nd + 36 Ar 150 Sm + 9 36 Ar 148 Sm + 10 Hydrides - 181 TaH + 182 WH + 183 WH + 185 ReH + Manuscript 11 Oxides 165 Ho 17 O+ 167 Er 16 O+ 167 Er 17 O+ 169 Yb 17 O+ - 12 166 Er 16 O+ 166 Er 17 O+ 168 Er 16 O+ 170 Tm 16 O+ 149 16 17 + 150 16 17 + 153 16 17 + 13 Dioxides Sm O O Sm O O 151 16 17 + Eu O O 150 16 16 + 150 16 17 + Eu O O 154 16 16 + 14 - Sm O O Nd O O 152 16 16 + Sm O O Sm O O 15 150 Nd 16 O16 O+ 151 Eu 16 O16 O+ 154 Gd 16 O16 O+ 170 14 + 16 Nitrides 168 14 + 169 14 + Er N 172 14 + - Er N Tm N 170 14 + Yb N 17 Yb N 164 19 + 18 Fluorides 163 19 + Dy F 165 19 + 167 19 + - Dy F 164 19 + Ho F Er F 19 Er F 20 Others - Composed ions, Chlorides (Nd, Sm, Eu), Hydroxides (Ho, Er, Tm) Accepted 21 22 23 Table 2 24 25 26 27 28 29 30 31 32 33 34 Spectrometry 35 36 37 38 39 40
41 Atomic 42 43 44 45 46 47 48 49 50 51 Analytical 52 53
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1 2 Reagent Concentration W (pg/mL) ** -1 3 HF 26 mol.L 3 * -1 4 HNO 3 15 mol.L 0.8 5 HCl * 10 mol.L -1 0.07 6 H2O2 30 % 0.01 7 H2O MilliQ - 0.001 8 9
10 Table 1 Manuscript 11 12 13 14 15 16 17 18 19 20 Accepted 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Spectrometry 35 36 37 38 39 40
41 Atomic 42 43 44 45 46 47 48 49 50 51 Analytical 52 53
54 of 55 56 57 58 59 60 1 Journal Page 25 of 36 Journal of Analytical Atomic Spectrometry
1 2 Step Acid Volume Eluted elements 3 4 Cleaning 2 mol.L -1 HF - 4 mol.L -1 HCl 40 mL 5 H O 40 mL 6 The cleaning cycle 2 -1 -1 7 is repeated a 4 mol.L HNO 3 - 0.5 mol.L HF 40 mL 8 second time H2O 40 mL 9
Resin Manuscript 10 2 mol.L -1 HF - 4 mol.L -1 HCl 40 mL 11 equilibration 12 Major elements, Ba, Sample -1 13 0.6 mol.L HF - 0.36% H O 16.6 mL Pb, Cr, Co, Ni, Cu, Zn, introduction 2 2 14 Rb, Sr, Ta, Re -1 15 Washing 1 mol.L HCl - 2% H 2O2 70 mL REE, Ti, Al 16 -1 -1 W Elution 4 mol.L HNO 3 - 0.5 mol.L HF 60 mL W (+Mo) 17 18 19 20 Accepted 21 Table 3 22 23 24 25 26 27 28 29 30 31 32 33 34 Spectrometry 35 36 37 38 39 40
41 Atomic 42 43 44 45 46 47 48 49 50 51 Analytical 52 53
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1 2 Cup L4 L3 L2 L1 C H1 H2 H3 H4 3 Mass 178 179 - 182 183 184 186 188 - 4 Element Hf Hf - W W W + Os W + Os Os - 5 6 7 8 Table 4 9
10 Manuscript 11 12 13 14 15 16 17 18 19 20 Accepted 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Spectrometry 35 36 37 38 39 40
41 Atomic 42 43 44 45 46 47 48 49 50 51 Analytical 52 53
54 of 55 56 57 58 59 60 1 Journal Page 27 of 36 Journal of Analytical Atomic Spectrometry
1
2 182 184 183 184 186 184 δ(2/4) δ(3/4) δ(6/4) 1 δ W/ W 2SD δ W/ W 2SD δ W/ W 2SD 1 2SD 1 2SD 1 2SD δ.amu 2SD 3 (amu ) (amu ) (amu ) 4 AGV-1 -0.48 0.12 -0.27 0.05 0.58 0.29 0.24 0.06 0.27 0.05 0.29 0.15 0.27 0.05 -0.37 0.13 -0.18 0.06 0.44 0.31 0.19 0.07 0.18 0.06 0.22 0.16 0.20 0.04 5 -0.44 0.10 -0.23 0.07 0.54 0.28 0.22 0.05 0.23 0.07 0.27 0.14 0.24 0.05 6 -0.40 0.14 -0.19 0.05 0.46 0.32 0.20 0.07 0.19 0.05 0.23 0.16 0.21 0.04 7 -0.50 0.12 -0.24 0.06 0.46 0.30 0.25 0.06 0.24 0.06 0.23 0.15 0.24 0.02 8 Mean 9 0.23 0.02 AGV-2 -0.75 0.14 -0.37 0.06 0.76 0.31 0.37 0.07 0.37 0.06 0.38 0.16 0.37 0.01 10 Manuscript -0.71 0.12 -0.38 0.05 0.66 0.27 0.36 0.06 0.38 0.05 0.33 0.14 0.36 0.05
11 -0.66 0.14 -0.36 0.05 0.76 0.26 0.33 0.07 0.36 0.05 0.38 0.13 0.36 0.05
12 -0.74 0.08 -0.38 0.06 0.70 0.36 0.37 0.04 0.38 0.06 0.35 0.18 0.37 0.03
13 -0.62 0.12 -0.33 0.07 0.76 0.32 0.31 0.06 0.33 0.07 0.38 0.16 0.34 0.07
14 Mean 0.36 0.01 15 G2 -0.06 0.10 0.06 0.06 -0.06 0.25 0.03 0.05 -0.06 0.06 -0.03 0.13 -0.02 0.09 -0.05 0.12 0.02 0.05 -0.11 0.39 0.02 0.06 -0.02 0.05 -0.06 0.20 -0.02 0.08 16 0.00 0.08 0.01 0.05 -0.02 0.34 0.00 0.04 -0.01 0.05 -0.01 0.17 -0.01 0.01 17 0.04 0.14 0.03 0.06 -0.06 0.34 -0.02 0.07 -0.03 0.06 -0.03 0.17 -0.03 0.01 18 -0.06 0.12 0.00 0.06 -0.08 0.28 0.03 0.06 0.00 0.06 -0.04 0.14 0.00 0.07 19 Mean 20 0.02 0.01 Accepted 0.18 0.10 0.36 0.09 0.10 0.18 21 PCC-1 0.11 0.09 -0.02 -0.05 -0.09 -0.01 -0.05 0.08 0.16 0.20 0.12 0.12 -0.22 0.40 -0.08 0.10 -0.12 0.12 -0.11 0.20 -0.10 0.04 22 0.00 0.16 0.00 0.14 -0.04 0.42 0.00 0.08 0.00 0.14 -0.02 0.21 -0.01 0.02
23 Mean 0.05 0.03 24 W1 -0.17 0.14 -0.04 0.06 0.32 0.34 0.08 0.07 0.04 0.06 0.16 0.17 0.09 0.12 25 -0.16 0.13 -0.08 0.04 0.21 0.35 0.08 0.07 0.08 0.04 0.10 0.18 0.09 0.02
26 -0.14 0.12 -0.09 0.05 0.20 0.38 0.07 0.06 0.09 0.05 0.10 0.19 0.09 0.03
-0.16 0.14 -0.07 0.07 0.18 0.30 0.08 0.07 0.07 0.07 0.09 0.15 0.08 0.02 27 -0.18 0.16 -0.10 0.07 0.14 0.34 0.09 0.08 0.10 0.07 0.07 0.17 0.09 0.03 28 29 Mean 0.09 0.01 30 BCR-1 -0.24 0.12 -0.12 0.05 0.31 0.22 0.12 0.06 0.12 0.05 0.16 0.11 0.13 0.05 -0.24 0.12 -0.13 0.04 0.30 0.27 0.12 0.06 0.13 0.04 0.15 0.14 0.13 0.03 31 -0.20 0.10 -0.10 0.06 0.24 0.26 0.10 0.05 0.10 0.06 0.12 0.13 0.11 0.02 32 -0.32 0.12 -0.14 0.05 0.34 0.28 0.16 0.06 0.14 0.05 0.17 0.14 0.16 0.03
33 0.14 0.07 0.26 0.07 0.07 0.13 -0.24 -0.15 0.34 0.12 0.15 0.17 0.15 0.05 Spectrometry
34 Mean 0.14 0.01 35 BE-N -0.18 0.08 -0.11 0.03 0.19 0.45 0.09 0.04 0.11 0.03 0.10 0.23 0.10 0.02 36 -0.14 0.06 -0.09 0.03 0.26 0.50 0.07 0.03 0.09 0.03 0.13 0.25 0.10 0.06
37 -0.20 0.10 -0.10 0.02 0.18 0.38 0.1 0.05 0.10 0.02 0.09 0.19 0.10 0.01
38 -0.22 0.08 -0.10 0.04 0.18 0.42 0.11 0.04 0.10 0.04 0.09 0.21 0.10 0.02
-0.14 0.06 -0.09 0.04 0.16 0.38 0.07 0.03 0.09 0.04 0.08 0.19 0.08 0.02 39 40 Mean 0.09 0.01 Allende 0.06 0.02 0.29 0.03 0.02 0.14 0.33 0.10 41 -0.82 -0.36 0.58 0.41 0.36 0.29 Atomic 42 -0.81 0.05 -0.35 0.02 0.55 0.30 0.40 0.03 0.35 0.02 0.28 0.15 0.32 0.10 43 -0.81 0.06 -0.36 0.03 0.56 0.26 0.41 0.03 0.36 0.03 0.28 0.13 0.32 0.11 Mean 44 0.32 0.03 0.08 0.03 0.36 0.04 0.03 0.18 45 Dhajala -0.51 -0.16 0.15 0.25 0.16 0.07 0.12 0.13 0.08 0.03 0.37 0.04 0.03 0.19 0.15 0.13 46 -0.56 -0.19 0.21 0.28 0.19 0.10 Mean 0.13 0.05 47 Gibeon -0.70 0.08 -0.20 0.03 0.51 0.60 0.35 0.04 0.20 0.03 0.25 0.30 0.23 0.07 48 -0.73 0.06 -0.20 0.04 0.23 0.37 0.37 0.03 0.20 0.04 0.12 0.19 0.16 0.11 49 -0.60 0.07 -0.13 0.03 0.36 0.51 0.30 0.04 0.13 0.03 0.18 0.26 0.16 0.07 50 -0.61 0.08 -0.17 0.04 0.32 0.42 0.30 0.04 0.17 0.04 0.16 0.21 0.17 0.01 51 -0.58 0.09 -0.12 0.04 0.33 0.73 0.29 0.05 0.12 0.04 0.16 0.37 0.14 0.06 Analytical 52 -0.53 0.09 -0.15 0.06 0.22 0.75 0.27 0.05 0.15 0.06 0.11 0.38 0.13 0.06 53 Mean 0.16 0.02
54 of 55 Table 5 56 57 58 59 60 1 Journal Journal of Analytical Atomic Spectrometry Page 28 of 36
1 2 3 4 5 6 7 8 9
10 Manuscript 11 12 13 14 15 16 17 18 19 20 Accepted 21 22 23 24 25 26 27 28 29 Figure 1 82x53mm (300 x 300 DPI) 30 31 32 33 34 Spectrometry 35 36 37 38 39 40
41 Atomic 42 43 44 45 46 47 48 49 50 51 Analytical 52 53
54 of 55 56 57 58 59 60 Journal Page 29 of 36 Journal of Analytical Atomic Spectrometry
1 2 3 4 5 6 7 8 9
10 Manuscript 11 12 13 14 15 16 17 18 19 20 Accepted 21 22 23 24 25 Figure 2 26 170x90mm (300 x 300 DPI) 27 28 29 30 31 32 33 34 Spectrometry 35 36 37 38 39 40
41 Atomic 42 43 44 45 46 47 48 49 50 51 Analytical 52 53
54 of 55 56 57 58 59 60 Journal Journal of Analytical Atomic Spectrometry Page 30 of 36
1 2 3 4 5 6 7 8 9
10 Manuscript 11 12 13 14 15 16 17 18 19 20 Accepted 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Spectrometry 35 36 37 38 39 40
41 Atomic 42 43 44 45 46 47 Figure 3 83x127mm (300 x 300 DPI) 48 49 50 51 Analytical 52 53
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10 Manuscript 11 12 13 14 15 16 17 18 19 20 Accepted 21 22 23 24 25 26 27 28 29 30 Figure 4 31 84x57mm (300 x 300 DPI) 32 33
Spectrometry 34 35 36 37 38 39 40
41 Atomic 42 43 44 45 46 47 48 49 50 51 Analytical 52 53
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10 Manuscript 11 12 13 14 15 16 17 18 19 20 Accepted 21 22 23 24 25 26 27 28 Figure 5 29 83x51mm (300 x 300 DPI) 30 31 32 33 34 Spectrometry 35 36 37 38 39 40
41 Atomic 42 43 44 45 46 47 48 49 50 51 Analytical 52 53
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10 Manuscript 11 12 13 14 15 16 17 18 19 20 Accepted 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Spectrometry 35 Figure 6 36 84x71mm (300 x 300 DPI) 37 38 39 40
41 Atomic 42 43 44 45 46 47 48 49 50 51 Analytical 52 53
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10 Manuscript 11 12 13 14 15 16 17 18 19 20 Accepted 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Spectrometry 35 36 37 38 39 40
41 Atomic 42 43 44 45 46 47 Figure 7 85x118mm (300 x 300 DPI) 48 49 50 51 Analytical 52 53
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10 Manuscript 11 12 13 14 15 16 17 18 19 20 Accepted 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Spectrometry 35 36 37 38 39 Figure 8 40 85x83mm (300 x 300 DPI) 41 Atomic 42 43 44 45 46 47 48 49 50 51 Analytical 52 53
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10 Manuscript 11 12 13 14 15 16 17 18 19 20 Accepted 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Spectrometry 35 36 37 38 39 40
41 Atomic 42 43 44 45 46 47 Figure 9 79x162mm (300 x 300 DPI) 48 49 50 51 Analytical 52 53
54 of 55 56 57 58 59 60 Journal