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• We report in situ S isotope analysis for multiple types of sulfides by LA-MC-ICPMS. • In situ S isotope analysis is applied to the study of the Erlihe Zn-Pb ore deposit. • Sulfur of the massive ores is likely sourced from the TSR process for the deposit. Sulfur isotopic composition is useful for tracing sources of ore-forming materials. In situ sulfur isotope analysis by laser ablation coupled with multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) has an advantage over traditional bulk analysis in tracing sources of sulfur in an ore deposit that has complex mineral types and multiple ore-forming processes. However, in using this method, matrix effects exist widely for sulfides from ore deposits. In this work, matrix effects of different sulfides were examined by matrix-unmatched tests, in which the δ34S values of different types of sulfides were calibrated against a laboratory pyrite standard. The results show that the δ34S values of pyrrhotite, chalcopyrite, molybdenite, sphalerite, and arsenopyrite are in agreement with the reference values, suggesting that the matrix effect was negligible. However, a significant matrix effect occurred in the analyses of Ag 2 S and galena, leading to significant deviations in δ34S values of up to 1.2‰ and 3.2‰, respectively. The matrix effect occurred not only during the laser ablation stage but also during the transition of ions into the mass spectrometer, resulting in significant space charge effects caused by heavy-mass elements. Thus, pyrite can be used as an external bracketing standard for sulfides that do not have a heavy-mass matrix. Based on our matrix-effect study, the following available external standards were selected for the in situ sulfur isotope analysis of complex-type minerals from the Erlihe Zn-Pb deposit. The coarse-grained sphalerite grains (Sph1) and euhedral to subhedral pyrite grains (Py1) from massive ores have δ34S values ranging from 9.2‰ to 18.1‰. Such heavy sulfur isotopic compositions indicate the derivation of sulfur from the deposits of seawater sulfate, related to a thermochemical reducing process. Fine-grained sphalerite (Sph2) and pyrite (Py2) from vein and disseminated ores coexist with pyrrhotite and chalcopyrite, and have relatively light sulfur isotopic compositions, with δ34S values of about 7‰. The slightly positive δ34S values are similar to those of sulfides from sulfide-rich quartz veins, which contain δ34S values of about 4‰, and granodiorite rocks, with δ34S values of about 6‰. Based on previous studies, the light sulfur of the late-stage sulfides may have resulted from a metamorphic or magmatic hydrothermal event during the Indosinian orogeny. In situ sulfur analysis by LA-MC-ICPMS provides new evidence for sources of sulfur from each stage of mineralization in the Erlihe deposit, suggesting that this is a promising method for studying complex ore deposits. [ABSTRACT FROM AUTHOR]

In this work, we improved the sensitivity of a multi-collector-inductively coupled plasma mass spectrometry system by increasing the vacuum of the expansion chamber using a high-speed EH mechanical booster pump (EH500, 500 m3 h−1, BOC Edwards) in conjunction with a standard E2M80 pump (80 m3 h−1, BOC Edwards). The vacuum was improved from 1.0 mbar to less than 0.5 mbar. The sample ion yield for heavy isotopes, such as those of Pb, was improved from 0.047% to 0.072% in the wet-plasma mode (sample uptake rate, 113 μL min−1), and from 1.35% to 1.84% in the dry-plasma mode (sample uptake rate 105 μL min−1); the variation in the background intensity was less than 1.3 mV for all the Faraday cups. Thus, the sample ion yield in the wet-plasma mode was enhanced more effectively than that in the dry-plasma mode owing to a slightly larger orifice in the wet cone setup. The accuracies for all the isotopes tested, including those of non-traditional metal ones, in both modes were identical to previously published data within an error of 2 s. These results indicate that improving the vacuum at the interface has no effect on the accuracy of isotope measurements and is an effective method for improving the detectability of isotopic compositions for bulk solution analysis with low element contents and the spatial resolution for measurements performed using the laser-ablation sampling technique. This work could provide an alternative for laboratories with a similar device, when tackling samples with low contents. [ABSTRACT FROM AUTHOR]

Silicon isotope analysis traditionally uses a standard-sample bracketing (SSB) method that relies upon greater instrument stability than can be consistently expected. The following proposed method reduces the level of instrumental stability required for the analysis process and provides a valid solution for high-precision and accurate studies of Si isotopic compositions. Rock samples were dissolved by using alkali fusion and acidification. Silicon isotopes were purified with an ion exchange resin. Interfering peaks for isotopes were separated by using a Nu Plasma 1700 multi-collector inductively coupled plasma mass spectrometry (MS) system in high-resolution mode ( M/Δ M > 8000 RP). Two magnesium isotopes (Mg and Mg) and three silicon isotopes (Si, Si, and Si) were analyzed in the same data collection cycle. Mg isotopes were used as an internal standard to calibrate the mass discrimination effects in MS analysis of Si isotopes in combination with the SSB method in order to reduce the effects of MS interference and instrumental mass discrimination on the accuracy of measurements. The conventional SSB method without the Mg internal standard and the proposed SSB method with Mg calibration delivered consistent results within two standard deviations. When Mg was used as an internal standard for calibration, the analysis precision was better than 0.05 ‰ amu. [ABSTRACT FROM AUTHOR]

Lead isotopic compositions of international silicate glasses, feldspar and copper-based samples are obtained using femtosecond laser ablation multiple collector inductively coupled plasma mass spectrometry (fLA-MC-ICPMS). Some international glass standards for the microanalysis are applied to evaluate the method reported here. The Pb isotopic composition of these NIST glasses (SRM 610, 612, 614), USGS (BHVO-2G, BCR-2G, BIR-1G and GSD-1G) and MPI-DING glasses (GOR132-G, KL2-G, T1-G, StHs60/80-G) agree well with recommended values in 2 s error. One of 15 copper-based metals is found to have homogenized Pb isotope data and can be used as an external calibration standard and quality control sample for chalcopyrite, ancient coins, etc., to trace the genesis of metal deposit and culture exchange among different dynasties (GBW02137, 208Pb/ 204Pb = 37.9661 ± 0.0005 (2 s), 207Pb/ 204Pb = 15.5770 ± 0.0002 (2 s), 206Pb/ 204Pb = 17.7462 ± 0.0002 (2 s)). We also prepared a feldspar glass to serve as the external calibration standard/QC for Pb isotope analysis using fLA-MC-ICPMS. [ABSTRACT FROM AUTHOR]

A new matrix‐matched reference material (NWU‐Brt) with sulfur isotope ratios resembling those of natural barites has been developed for in situ S isotope measurements by laser ablation multi‐collector inductively coupled plasma‐mass spectrometry (LA‐MC‐ICP‐MS). A 100 g quantity of natural barite crystal was milled to ultra‐fine particles and sintered to a solid block using a fast hot‐pressing sintering technique (FHPS). We report δ34S ratios determined by isotope ratio mass spectrometry (IRMS), solution nebuliser multi‐collector inductively coupled plasma‐mass spectrometry (SN‐MC‐ICP‐MS) and LA‐MC‐ICP‐MS, involving up to six participating laboratories. The homogeneity of δ34S ratios of the synthesised barite was tested by LA‐MC‐ICP‐MS with an analytical spot size of 53 μm. The LA‐MC‐ICP‐MS results show that NWU‐Brt demonstrates a satisfactory homogeneous composition and is an appropriate material for calibrating δ34S ratios in barite. IRMS and SN‐MC‐ICP‐MS produced mean δ34S values of +14.17 ± 0.42‰ (2s) and +14.27 ± 0.23‰ (2s), respectively. The results of LA‐MC‐ICP‐MS analyses are consistent with the IRMS and SN‐MC‐ICP‐MS ratios within uncertainty. Overall, our results confirm the suitability of NWU‐Brt for the calibration of δ34S ratios in barite using LA‐MC‐ICP‐MS. [ABSTRACT FROM AUTHOR]

This study presents a practical method for high-precision Fe isotope determination without column chromatography purification for iron-dominated mineral samples using multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). A series of comparable experiments (with or without column chromatography) were performed to evaluate whether non-deviated Fe isotope ratios can be obtained directly by MC-ICP-MS using standard-sample bracketing (SSB) without column chromatography purification. Forty iron-dominated material/mineral samples (pure iron wire, pyrite, chalcopyrite, magnetite, hematite, siderite, goethite, pyrrhotite, arsenopyrite, specularite, ilmenite, limonite, lollingite, ilvaite, and Fe–Mn nodule) were investigated, and the results showed little bias in δ56Fe values compared with those of mineral materials via column chromatography purification, with Δδ56Fewithout–with ranging from −0.06‰ to +0.06‰. This means that Fe isotope ratios in Fe-dominated minerals can be achieved without column chromatography, due to the simple matrix and the stability of the machine by using the SSB method in high resolution wet plasma mode. The concentration effect and nitric acidity mismatch effects, as well as the matrix effect, were strictly assessed by MC-ICP-MS in high resolution wet plasma mode. Finally, a long-term reproducibility of better than ± 0.05‰ (n = 123, 2 sd) was achieved by repeatedly measuring pyrite without column chromatography over 6 months. Compared with the column chromatography purification method, the without column chromatography method significantly simplifies the chemical procedure and improves the efficiency of iron-dominated mineral Fe isotope analysis. [ABSTRACT FROM AUTHOR]

This study compares three zircon synthesis techniques (synthesis, high-temperature and high-pressure sintering and fast hot-pressing sintering) for the preparation of reference materials for Hf isotope analysis of zircon by laser ablation multi-collector inductively-coupled plasma mass spectrometry (LA-MC-ICP-MS). Ultrafine milled zircon powder particles doped with Yb2O3 produced by wet milling were used to synthesize zircon samples by using high-temperature and high-pressure sintering and fast hot-pressing sintering techniques. Li–Mo flux was necessary to obtain synthetic zircon grains. Zr signals for synthetic zircon grains and high-temperature and high-pressure sintered zircon are consistent with those of natural zircons but higher than that of fast hot-pressing sintered zircon, indicating that high-temperature and high-pressure sintered zircon has approximated the theoretical maximum density due to high pressure. The Hf isotopic compositions of high-temperature and high-pressure sintered and fast hot-pressing sintered zircon are comparable to those of the initial starting materials, whereas the Hf isotopes in synthetic zircon grains deviate slightly from those of the initial Hf solution. Compared with Hf isotope ratios obtained by SN-MC-ICP-MS, all preparation techniques give reliable LA-MC-ICP-MS results, suggesting that all synthetic zircon samples have great potential as both tools for in situ method development and isotopic reference materials. [ABSTRACT FROM AUTHOR]

In sample preparation and mass spectrometry analysis, sample dissolution, column chemistry, concentration mismatches, and matrix effects have significant potential for introducing analytical artifacts during Mg isotope analysis. Based on the low MgO content and undesirable matrix elements in felsic rocks, the development of well-characterized felsic standards is essential to reduce inter-laboratory mass bias, enable the assessment of data accuracy, and facilitate the comparison of chemical separation procedures in different laboratories. In this work, the homogeneity and long-term stability of two felsic rock standards, GSR-1 and RGM-2, were evaluated due to their low MgO contents. Furthermore, synthetic solutions with doped matrix elements were used to evaluate potential Mg isotope analytical artifacts using multi-collector inductively coupled plasma mass spectrometry. The accuracy and precision of Mg isotopic compositions in GSR-1 and RGM-2 were assessed by repeated measurements over twelve months. The long-term tests show that the Mg isotopic compositions of the two low MgO felsic rocks (GSR-1 and RGM-2) are homogenous among batches and can be used as low MgO reference materials for accuracy assessments of Mg isotopic analyses. The Mg isotopic compositions (δ26Mg) of GSR-1 and RGM-2 were marked as -0.223‰±0.053‰ (2s, n=50) and -0.184‰±0.058‰ (2s, n=50) respectively. [ABSTRACT FROM AUTHOR]

High-quality Sr isotope data are critically dependent on the quality of reference materials that are used for instrumental calibration and data monitoring during laser ablation (LA) multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) analysis. We have prepared a new natural calcite reference material MNP for in situ Sr isotope measurement by LA-MC-ICP-MS. Detailed textural examination and major element determination suggest that the MNP calcite reference material has no growth rim or zoning. Trace element analyses by LA-ICP-MS showed that the MNP calcite reference material has low Rb/Sr ratios, low amounts of heavy rare earth elements (HREEs) and high Sr contents. The MNP calcite reference material is homogeneous with respect to Sr isotopes based on a large number of measurements performed by single-grain solution nebulizer (SN)-MC-ICP-MS and LA-MC-ICP-MS. The traditional bulk isotope analyses by TIMS and SN-MC-ICP-MS yielded a mean 87Sr/86Sr ratio of 0.70617 ± 0.00005(2SD, n = 18). A total of 585 LA-MC-ICP-MS Sr isotope analyses on random calcite crystals show homogeneous Sr isotopic compositions with an average 87Sr/86Sr ratio of 0.70617 ± 0.00005 (2SD), identical with the solution-based data. These suggest that MNP calcite can be used as a potential reference material for microbeam Sr isotopic analysis. [ABSTRACT FROM AUTHOR]

In this study, we present a new method for the dissolution of silicate rocks by flux-free fusion using a boron nitride vessel in preparation for analysis of bulk rock trace elements; this method is especially applicable to felsic intrusive rocks. The method was evaluated by analyzing five intrusive rocks (GSP-2, GSP-1, G-2, GSR-1 and QLO-1) and five extrusive rocks (AGV-2, BCR-2, BHVO-2, GSR-3 and RGM-2). The optimum conditions for the fusion of intrusive rocks were determined to be heating at 1600 °C for 1 min, which is effective to break up strong Si–O bonds. The fused glasses were dissolved using HF/HNO3 acids in closed screw-top Savillex vials on a hotplate; no high-pressure PTFE digestion bomb was required. Zr and Hf were completely recovered from the granodiorite GSP-2 reference material in 6 hours at 150 °C, which was 8 times faster than the method using a conventional high-pressure PTFE digestion bomb at 190 °C. The precision (RSD%, 1 s) of the elemental determinations in nearly 92% of the analyzed samples was better than 4%. Replicate analyses (n = 3) of the reference materials indicated that most of the results agreed with the reference values within a relative error of ＜10%. Additionally, the flux-free fusion retained all the materials in solution and was valid for volatile elements. [ABSTRACT FROM AUTHOR]

In this study, lead isotopic ratios in bronze artifacts were non-matrix-matched determined directly by femtosecond laser ablation multi-collector inductively coupled plasma mass spectrometry (fsLA-MC-ICP-MS). We evaluated the necessity of matrix matching for lead isotope ratio analyses of bronzes by adopting thallium solution to correct mass discrimination during mass spectrometer measurements. Lead isotope ratios of four bronze reference materials were measured by fsLA-MC-ICP-MS to determine the quality of data when calibrating samples with standards having different physical characteristics and chemical compositions. The average 206 Pb/ 204 Pb, 207 Pb/ 204 Pb, 208 Pb/ 204 Pb, 207 Pb/ 206 Pb and 208 Pb/ 206 Pb ratios determined by fsLA-MC-ICP-MS were within 0.06% of that by solution nebulizer MC-ICP-MS (SN-MC-ICP-MS). The results indicate that accurate lead isotopic compositions could be obtained by fsLA-MC-ICP-MS technique after non-matrix-matched standards calibration. Additionally, the lead isotopic compositions are presented for five Chinese bronze reference materials using fsLA-MC-ICP-MS. Homogeneity of lead isotope distribution was expressed as the RSD range from 0.010% to 0.017% for 208 Pb/ 204 Pb, 207 Pb/ 204 Pb, 206 Pb/ 204 Pb ratios. Therefore, the five bronze materials could potentially serve as external calibration standards and quality control samples for in situ lead isotope measurements of ancient bronze artifacts. The fsLA-MC-ICP-MS technique could be applied to differentiate the high radiogenic lead in bronze artifacts from common lead. [ABSTRACT FROM AUTHOR]

We have prepared a large volume of pure, concentrated and homogeneous magnesium standard solution (GSB-Mg) to be used as a secondary reference standard by the magnesium isotope community. This new standard solution can also be used for quality assurance, including the development and validation of analytical procedures, preparation and test of analytical methods, quality control and training of analysts. The δ26Mg values relative to DSM3, measured by multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), are −2.038 ± 0.027‰ (n = 45, Lab 1), −2.024 ± 0.055‰ (n = 7, Lab 2), −2.078 ± 0.081‰ (n = 6, Lab 3), −2.037 ± 0.015‰ (n = 8, Lab 4), and −2.067 ± 0.039‰ (n = 12, Lab 5). The δ26Mg and δ25Mg values for the GSB-Mg standard solution are −2.049‰ and −1.056‰, with a combined expanded (k = 2) uncertainty of 0.049‰ and 0.028‰, respectively. These values show higher similarity to Mg isotopic compositions of carbonates and marine sediments compared to those of the mantle and crustal rocks, making the GSB-Mg solution a great reference material for Mg isotopic analysis of carbonates and marine sediments. [ABSTRACT FROM AUTHOR]

• Novel Si isotope tracer method deconvoluted feldspar dissolution and precipitation. • Feldspar backward reaction is insignificant at low temperatures. • Recommend forward dissolution rates only in low-temperature kinetics models. • This approach for weathering, geological carbon sequestration, and diagenesis. Here we show that the isotope tracer experimental method for kinetic studies, aided by the recent advance and accessibility of multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) analysis for non-traditional stable isotopes, can provide unidirectional dissolution rates at near-equilibrium conditions. For a long time, the only rates available at near-equilibrium were net reaction rates—dissolution rates minus precipitation rates. This is because the conventional experimental method of kinetic studies is based on element concentrations and can only provide net rates. The availability of unidirectional rates allows us to re-examine some fundamental concepts and practices of modeling weathering in geochemistry. In this study, we used the 29Si isotope tracer to conduct albite and K-feldspar dissolution experiments at near-equilibrium conditions in near-neutral pH solutions at 50 °C. Results show that the saturation indices (SI) of solutions approached zero with respect to albite and K-feldspar after ∼240–360 h (h), but 29Si/28Si ratios of the experimental solutions indicated continual dissolution for another 720–1440 h. The rates of total Si precipitation were much smaller than the rates of Si dissolution. The experimental solutions were supersaturated with respect to amorphous Al(OH) 3 , gibbsite, quartz, allophane, imogolite, and kaolinite. The SI of the solutions remained constant with respect to these phases while Al concentrations slightly decreased and Si concentrations slightly increased, indicating the coupled feldspar dissolution and precipitation of secondary phases, such as albite → amorphous Al(OH) 3 + quartz or albite → solution + Al-Si phase(s), instead of significant albite and K-feldspar precipitation (the reverse reaction) at 50 °C. Reaction path modeling of the temporal evolution of Si, Al, Na, and pH revealed that albite dissolution (without significant backward reaction) coupled with the precipitation of a secondary phase with a Si:Al ratio of ∼2:1 can successfully match the experimental data. Given the negligible feldspar precipitation reactions in low-temperature systems (e.g., T < 100 °C), we recommend modeling feldspar weathering using unidirectional forward rates together with secondary phase precipitation rates in near-equilibrium, feldspar-undersaturated systems. This can be accomplished with minor modifications in geochemical modeling software or input files. The coupled feldspar dissolution with secondary phase precipitation arrests the system in a near-equilibrium steady state. Using affinity-based rate equations such the classical linear Transition State Theory rate law or the Burch empirical relation together with far-from-equilibrium rate data will predict significant feldspar precipitation in solutions undersaturated but close to equilibrium with respect to feldspars, which is unlikely at near ambient temperatures. [ABSTRACT FROM AUTHOR]

In this study, we established a rapid acid digestion for determining Hf-Sr-Nd isotopic ratios of geological samples by using MC-ICP-MS. Conditions of 1600 °C for 1 min and 1400 °C for 1 min were adopted for fusing intrusive rocks and extrusive rocks, respectively. The rapid acid digestion technique is superior in digestion time compared with high-pressure PTFE bomb method. The procedural blanks of the method were also lower than that flux fusion. Replicate analyses of international certified reference materials (CRMs) indicate that isotopic ratios of 176Hf/177Hf, 87Sr/86Sr and 143Nd/144Nd agree well with previously published data. The external reproducibility (2SD, n = 5) of ten CRMs are ±0.000030 for 87Sr/86Sr, ±0.000030 for 143Nd/144Nd, and ±0.000018 for 176Hf/177Hf. [ABSTRACT FROM AUTHOR]

Abstract: Clastic sedimentary rocks are samples of the exposed continental crust. In order to characterize the crustal growth history of North China and its possible regional variations, 479 concordant detrital zircons in three sand samples from the lower reach of the Yellow River (which drains the Tibet–Qinghai Plateau, the Western Qinling Orogen, the Qilian Orogen and the North China Craton) and two sand samples from the Luan River and the Yongding River (which run entirely within the North China Craton) were measured for U–Pb age and Lu–Hf isotopic compositions by excimer laser-ablation ICP-MS and MC-ICP-MS. Although regional variations exist, concordant detrital zircons from the Yellow River reveal three major age groups of 2.1–2.5Ga, 1.6–2.0Ga, and 150–500Ma. Detrital zircons from the smaller Luan and Yongding Rivers show three broadly similar major age groups at 2.3–2.6Ga, 1.6–2.0Ga, and 140–350Ma, but with narrower age ranges. Compared to the Luan and Yongding River zircons, the Yellow River zircons are characterized by a significant number of Neoproterozoic grains. Although Hf isotopic compositions show both juvenile crustal growth and crustal reworking for all age groups, much of the crustal growth of North China occurred in the Neoarchean and Mesoproterozoic. All three rivers are characterized by a common prominent group of Hf crust formation model ages at 2.4–2.9Ga with a peak at 2.7–2.8Ga. A less significant age group lies between 1.4 and 1.8Ga for the Yellow River, and between 1.6 and 1.9Ga for the Yongding River and Luan River. Crustal growth rates based on Hf continental crust formation model ages suggest 45% and 90% of the present crustal volume was formed by 2.5Ga and 1.0Ga, respectively, for the drainage area of the Yellow River. In comparison, 60% and 98% of the present crustal volume of the North China Craton was generated by 2.5Ga and 1.0Ga, respectively, for the Luan and Yongding Rivers. The 2.7–2.8Ga age peak observed in all river samples agrees well with the coeval major peak for global crustal growth. However, the other suggested global peaks of crustal growth at 3.4 and 3.8Ga are insignificant in North China. Taken together with our previous studies of the Yangtze Craton, which show insignificant crustal growth at 2.7–2.8Ga, we suggest that these advocated worldwide crust formation peaks be re-examined and treated carefully. Our results also show that Phanerozoic zircons may have been derived from crustal sources separated from the mantle up to 2.0Ga ago before the zircons crystallized, suggesting long-term preservation, reworking and recycling of the continental crust. [Copyright &y& Elsevier]

• Silicate minerals make up ∼90% Earth's crust. • Using Si isotope ratios instead of Si concentrations greatly improve detection of reactions. • The isotope ratio method is hindered by the lack of accessibility of MC-ICP-MS. • ICP-QMS analysis of Si isotope ratios yields acceptable precision for reaction rate measurements. • Validated the method by analyzing reference solutions and albite hydrolysis experiments. Here we show that silicon isotope tracer kinetics experiments can be economically conducted with measurements of 29Si/28Si ratios in the experimental aqueous solutions using Quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) with sufficient precision. Although the isotope tracer method promises orders of magnitude improved detection sensitivity of reactions, its application has been hampered by the limited availability of multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) for Si isotope analysis. However, in Si isotope tracer kinetics experiments, dissolution rates are often derived from isotope fractional abundance increments by as much as 0.5 unit (equivalent to 50%) and the method essentially relies on the difference in isotope ratios over a period of time, which render uncertainties in < ±0.01 fraction (or ±1%) in Si isotope abundances tolerable. Laboratory-measured silicate dissolution rates typically carry uncertainties of more than ±25% and with even poorer intra- and inter-laboratory replications. These special situations of kinetics experiments circumvent the conventional concerns of using Q-ICP-MS to measure isotope ratios. To test this hypothesis, we conducted two experiments. The first used Q-ICP-MS to measure a set of mixing solutions or reference solutions with known isotope compositions. The results show that the difference is an average of ±0.009 in f 29. A second test used both MC-ICP-MS and Q-ICP-MS to measure the 29Si/28Si ratios in experimental solutions of albite dissolution. Ten albite dissolution experiments were conducted at 50 °C and pH 8.8. Student t -test showed that the rates calculated from the two analytical data sets have no statistically significant differences at the 95% confidence level. These results demonstrate that the Q-ICP-MS measurements of 29Si/28Si ratios produced tolerable uncertainties for determining silicate dissolution rates. However, the cost is significantly reduced and more significantly, the reduced wait time makes isotope tracer experiments more feasible. Silicate minerals make up 90% of the Earth's crust. The kinetics of silicate-water reactions is of paramount significance to many society's mega-environmental enterprises. This method to conduct Si isotope tracer experiments, as well as the possibility to use this approach for other non-traditional stable isotopes, will have significant impact on geochemical kinetics studies. [ABSTRACT FROM AUTHOR]