研究者詳細 - 牧嶋　昭夫

論文 - 牧嶋　昭夫

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Precise determination of Pb isotope ratios by simple double spike MC-ICP-MS technique without Tl addition 査読

Akio Makishima, B. Nagender Nath, Eizo Nakamura

Journal of Analytical Atomic Spectrometry 22 ( 4 ) 407 - 410 2007年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

A double-spike multicollector ICP-MS ( DS-MC-ICP-MS) technique for Pb isotope analysis without T1 addition is established and its analytical performance is examined in detail. This simple DS-MC-ICP-MS technique using 20 ng ml(-1) gave averages of 16.9417, 15.4988 and 36.7196 with reproducibilities of 0.007, 0.008 and 0.009% ( RSD, n = 35), respectively, for Pb-206/Pb-204, Pb-207/Pb-204 and Pb-208/Pb-204 in NIST 981 solution, corresponding to consumption of 4 ng of Pb in a pair of spiked and non-spiked measurements. The average is consistent with those obtained by previous studies by DS-TIMS and DS-MC-ICP-MS with T1 addition. The reproducibility ( RSD %) of Pb-206/Pb-204, Pb-207/Pb-204 and Pb-208/Pb-204 improves from 0.26, 0.54 and 0.69% to 0.0022, 0.0030 and 0.0029% as the Pb consumption during analysis increases from 20 pg to 11 ng. The reproducibility with 11 ng is similar to or even better than those by DS-TIMS, MC-ICP-MS with T1 addition, or with DS-T1 addition. The accuracy of the simple DS-MC-ICP-MS technique for Pb, including the column chemistry, is further confirmed by analysis of actual silicate sample, JB-3.

DOI： 10.1039/b616021b

Accurate determination of ²³⁴U/²³⁸U and ²³⁰Th/²³²Th for U-Th disequilibria studies by MC-ICP-MS with simple bracketing 査読

Akio Makishima, Takele A. Chekol, Eizo Nakamura

Journal of Analytical Atomic Spectrometry 22 ( 11 ) 1383 - 1389 2007年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

Accurate determination methods for U-234/U-238 and Th-230/Th-232 using multiple collector (MC) ICP-MS with a single secondary electron multiplier through a retarding potential quadrupole filter (RPQ-SEM) have been developed. The RPQ-SEM yield and the instrumental mass discrimination were simultaneously corrected by the simple bracketing method which utilizes accurately determined standard solutions measured by TIMS. For the bracketing and as an evaluation of the precision of the method, four standard solutions, NBL-145 U and U-m for U, and Th-I and Th-II for Th, were prepared, and NBL-145 U and Th-I were used as bracketing standards. The U and Th amounts of 0.5-21 ng and 0.6-21 ng used in U-m and Th-II analyses gave intermediate precisions (2RSD) of 0.85-0.06 and 0.88-0.19%, respectively, and vary from TIMS measurements by <0.35 and <1.1%, respectively, which agrees with error values in TIMS analyses. To achieve similar intermediate precisions of 0.2 and 0.6% (2RSD) in the U and Th isotope analyses to that of TIMS, 3 and 2 ng of U and Th are sufficient. When only the isotope analysis is performed, the required amounts of U and Th can be reduced by half. The precision of the isotope analyses, as well as the concentration determinations, were further confirmed by analyses of U and Th separated from the GSJ standard basalt, JB-2.

DOI： 10.1039/b706907c

Purification of Hf in silicate materials using extraction chromatographic resin, and its application to precise determination of ¹⁷⁶Hf/ ¹⁷⁷Hf by MC-ICP-MS with ¹⁷⁹Hf spike 査読

Yinghuai Lu, Akio Makishima, Eizo Nakamura

Journal of Analytical Atomic Spectrometry 22 ( 1 ) 69 - 76 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

A two-stage column purification method for Hf from Zr and other elements in silicate samples using the extraction chromatographic resin, UTEVA has been developed. In the first column, using an anion-exchange resin, AG 1X8, Hf, Zr and Ti were collected. In the second, using UTEVA, and after eliminating F- by evaporation with HClO4 and re-dissolution with H2O2 HNO3, Hf was purified from Ti and Zr, based on characteristic of the UTEVA resin that Hf distribution coefficient (K-d) decreases from 770 to 40, while Kd of Zr decreases less from 890 to 200, in 9 and 6 mol l(-1) HNO3, respectively. The recovery yield of Hf was B88% and total blank was similar to 4 pg. A MC-ICP-MS Hf isotope ratio determination method was also developed, which uses 179 Hf spike for simultaneous determination of the Hf concentration and Hf-176/Hf-177 ratio. Combining the chemistry and ICP-MS techniques, Hf-176/Hf-177 ratios in silicate reference materials were determined with and without the spike, which gave identical results, showing the applicability of this method.

DOI： 10.1039/b610197f

Determination of Os and Re isotope ratios at subpicogram levels using MC-ICPMS with solution nebulization and multiple ion counting 査読

Akio Makishima, Eizo Nakamura

Analytical Chemistry 78 ( 11 ) 3794 - 3799 2006年6月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

A precise and accurate determination method of Os-187/ Os-188, Os-189/Os-188, and Re-185/Re-187 ratios of down to 0.2 pg of Os and 0.08 pg of Re using multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) with multiple ion counting has been developed. Os and Re were introduced into MC-ICPMS as 0.5 mol L-1 HF solutions through the desolvator, and Re-185, Os-187, Os-188, and Os-189 ions were detected simultaneously by four channeltrons. The Os and Re ratios were determined by the standard bracketing method, in which channeltron yields and mass discrimination factors are corrected together. Os and Re memories after 800-s wash were < 0.1% and negligible, typically 0.02 and 0.03%, respectively. Isotope ratios of Os-187/ Os-188, Os-189/Os-188, and Re-185/Re-187 were constant within error in the concentration ranges of 1-100, 1-40, and 0.4-5 pg mL(-1) with reproducibility (1 sigma) of 2.7-0.14, 0.33-0.10, and 0.41-0.19%, respectively. For analysis of larger amounts of Os and Re, the Faraday cup measurement was employed. The precision and reproducibility obtained in this study are comparable to those of N-TIMS and better than MC-ICPMS achieved so far with a capability of higher sample throughput with simpler sample preparation.

DOI： 10.1021/ac060183t

Determination of major, minor and trace elements in silicate samples by ICP-QMS and ICP-SFMS applying isotope dilution-internal standardisation (ID-IS) and multi-stage internal standardisation 査読

Akio Makishima, Eizo Nakamura

GEOSTANDARDS AND GEOANALYTICAL RESEARCH 30 ( 3 ) 245 - 271 2006年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：GEOSTANDARDS

A method for the determination of major, minor and trace elements in silicate samples by ICP-QMS and ICP-SFMS applying isotope dilution-internal standardisation (ID-IS) and multi-stage internal standardisation has been developed. Samples with an enriched isotope of Sm-149(spike) were decomposed by a HF/HClO4 mixture and stepwise drying and finally diluted. In ID-IS for trace element analyses by Q-pole type ICP-MS (ICP-QMS), the Sm concentration was determined by ID, while other trace elements (Li, Be, R6, Sr, Y, In, Cs, Ba, La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Tl, Pb, Bi, Th and U) were determined using the Sm-149 intensity as an internal standard. Major and minor elements were determined by multi-stage internal standardisation, with Na, Mg, Al, R Ca, V, Mn, Fe and Co measured by sector magnetic field type ICP-MS (ICP-SFMS) at middle resolution (MR; M/Delta M = similar to 3000) using Sr determined by ICP-QMS in the sample as the internal standard. Potassium, Sc, Ni, Cu, Zn and Ga were measured at high resolution (HR; M/Delta M similar to 7500) using the Sr concentration obtained by ICP-QMS or the Mn concentration obtained by ICP-SFMS at MR as internal standard. The merit of ID-IS is that accurate dilution of the sample is not required. Matrix effects on elemental ratios down to a dilution factor (DF) of 600 were not observed in either types of mass spectrometry. Pseudo-flow injection (FI), where transient signals were integrated, was used in ICP-QMS, while conventional continuous sample introduction was used in ICP-SFMS, resulting in total required sample solutions of 0.026 ml and 0.08 ml, respectively. Detection limits were low enough to determine these elements in depleted ultramafic rocks, and typical reproducibilities for basalts were 3% (Li-Be), 11% (Rb-U), 5% (In, Tl and Bi), 7% (Sc-Ga) and 3% (major elements). Carbonaceous chondrites including Orgueil (Cl1), Murchison (CM2) and Allende (CV3), as well as reference materials, JB-1, -2,-3, JA-1, -2,-3 and JP-1 (GSJ), BHVO-1, AGV-1, PCC-1 and DTS-1 (USGS), were analysed to show the applicability of this method.

DOI： 10.1111/j.1751-908X.2006.tb01066.x

Mg and Ca isotope fractionation during CaCO <inf>3</inf> biomineralisation 査読

Veronica T.C. Chang, R. J.P. Williams, Akio Makishima, Nick S. Belshawl, R. Keith O'Nions

Biochemical and Biophysical Research Communications 323 ( 1 ) 79 - 85 2004年10月

掲載種別：研究論文（学術雑誌）

The natural variation of Mg and Ca stable isotopes of carbonates has been determined in carbonate skeletons of perforate foraminifera and reef coral together with Mg/Ca ratios to assess the influence of biomineralisation processes. The results for coral aragonite suggest its formation, in terms of stable isotope behaviour, approximates to inorganic precipitation from a seawater reservoir. In contrast, results for foraminifera calcite suggest a marked biological control on Mg isotope ratios presumably related to its low Mg content compared with seawater. The bearing of these observations on the use of Mg and Ca isotopes as proxies in paleoceanography is considered. © 2004 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2004.08.053

Suppression of Zr, Nb, HF, and Ta co-precipitation during HF digestion of Ca-rich geological materials 査読

Tanaka R, Kitagawa H, Makishima A, Nakamura E

Geochimica Et Cosmochimica Acta 67 ( 18 ) A475 - 1463 2003年

Purification of Mg from low-Mg biogenic carbonates for isotope ratio determination using multiple collector ICP-MS 査読

Veronica T.C. Chang, Akio Makishima, Nick S. Belshaw, R. Keith O'Nions

Journal of Analytical Atomic Spectrometry 18 ( 4 ) 296 - 301 2003年

掲載種別：研究論文（学術雑誌）

A technique for separation of Mg, with 100% yield from low-Mg biogenic carbonates has been developed suitable for high precision analysis of Mg isotopes by multiple-collector inductively coupled plasma mass spectrometry. Two separate stages of ion-exchange chromatography were carried out using cation exchange resin, AG50W-X12 with a Mg recovery >99.9%. The repeatability of the Mg isotope ratio measurement using this technique including chemistry and mass spectrometry is ±0.14‰ on δ26Mg and ±0.09‰ on δ25Mg at 95% confidence. This was demonstrated using a synthetic solution (Na : Mg : Ca : Sr = 2 : 1 : 100 : 1 in weight) over a period of six months. The robustness of the technique was further assessed by replicate analyses of three natural samples, seawater, foraminifera and dolomite. A total variation over 4.5‰ on δ26Mg was observed and the Mg isotope composition of seawater was 2.59 ± 0.14‰ on δ26Mg and 1.33 ± 0.09‰ on δ25Mg which were the highest isotope ratios among the samples measured. © The Royal Society of Chemistry 2003.

DOI： 10.1039/b210977h

Suppression of Zr, Nb, Hf and Ta coprecipitation in fluoride compounds for determination in Ca-rich materials 査読

Ryoji Tanaka, Akio Makishima, Hiroshi Kitagawa, Eizo Nakamura

Journal of Analytical Atomic Spectrometry 18 ( 12 ) 1458 - 1463 2003年

掲載種別：研究論文（学術雑誌）

We have evaluated recovery yields of Zr, Nb, Hf and Ta, which are called high field strength elements (HFSE), in the synthetic Ca-Al-Mg-HF solution system using two different methods: at <70°C in an ultrasonic-bath (denoted as the ultrasonic method) and at 205°C using a TFE Teflon® bomb (denoted as the bomb method). Full recovery of HFSE into the supernatant HF solution was not achieved in cases where fluorite (CaF2) forms in the precipitate in both methods and sellaite (MgF2) forms in the ultrasonic method. In order to suppress fluorite precipitation, an 'Al-addition method' was developed in which Al solution is added to the sample before decomposition to change the matrix solution to a composition in which no fluorite forms. Using the Al-addition method, HFSE concentrations of Ca-rich materials were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) by an isotope dilution method for Zr and Hf and by a calibration curve method for Nb and Ta. Furthermore, we found isotopic disequilibria of Zr and Hf between sample and spike without Aladdition for Ca-rich samples, and that the Al-addition method was very effective in achieving isotopic equilibria and full recovery of HFSE, resulting in high accuracy in their determination. © The Royal Society of Chemistry 2003.

DOI： 10.1039/b309948b

High precision measurement of titanium isotope ratios by plasma source mass spectrometry 査読

X. K. Zhu, A. Makishima, Y. Guo, N. S. Belshaw, R. K. O'Nions

International Journal of Mass Spectrometry 220 ( 1 ) 21 - 29 2002年9月

掲載種別：研究論文（学術雑誌）

A method using multiple-collector inductively coupled plasma source mass spectrometry for the precise measurement of Ti isotope composition in natural materials has been developed. Instrumental mass discrimination is corrected using a "standard-sample bracketing" approach by expressing the isotope ratios of samples relative to those of the bracketing standard. Variations in 47Ti/46Ti, 48Ti/46Ti, 49Ti/46Ti and 50Ti/46Ti ratios of samples are expressed in ε units which are deviations in parts per 104 from the same isotope ratios of the reference material. The long-term repeatability at the 2 standard deviation level is 0.4, 0.6, 0.7 and 0.8 ε units in terms of 47Ti/46Ti, 48Ti/46Ti, 49Ti/46Ti and 50Ti/46Ti ratio measurements, respectively. The technique reported here makes it possible for the first time that both mass-dependent fractionation and isotope anomalies of Ti isotopes in natural materials can be measured to high precision. © 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S1387-3806(02)00767-4

Separation of titanium from silicates for isotopic ratio determination using multiple collector ICP-MS 査読

Akio Makishima, Xiang Kun Zhu, Nick S. Belshaw, R. Keith O'Nions

Journal of Analytical Atomic Spectrometry 17 ( 10 ) 1290 - 1294 2002年

担当区分：筆頭著者掲載種別：研究論文（学術雑誌）

A new separation method of Ti from silicate materials is presented that is suitable for the determination of natural Ti isotope variations using multi-collector inductively coupled plasma source mass spectrometry (MC-ICP-MS). This method makes possible for the first time the separation of Ti from natural materials, with high purity, high recovery and no introduction of artificial mass fractionation. Following sample decomposition using HF, Ti is separated using a three-column procedure. In the first column using an anion-exchange resin, AG 1X8, major elements and the majority of trace elements are separated. In the second column, after eliminating F- by evaporation with HClO4 and re-dissolution with H2O2-HNO3, Ti is separated from Zr and Hf using a liquid-liquid extraction resin, U/TEVA. In the third column, which is the same as the first column, trace amounts of Al and P are further removed. Recovery yields were almost unity, and no Ti isotope fractionation occurred from the overall chemical processing. The reproducibilities (2σ) of the Ti isotope ratio measurement for a meteorite (eucrite) and a lamproite were <0.5ε for ε47Ti, ε48Ti and ε49Ti, and <1ε for ε50Ti, which were comparable to those for the pure Ti standard solution.

DOI： 10.1039/b204349a

A group separation method for ruthenium, palladium, rhenium, osmium, iridium, and platinum using their bromo complexes and an anion exchange resin 査読

A. Makishima, M. Nakanishi, E. Nakamura

Analytical Chemistry 73 ( 21 ) 5240 - 5246 2001年11月

担当区分：筆頭著者掲載種別：研究論文（学術雑誌）

A new group separation method for Re and PGE (Ru, Pd, Os, Ir, Pt) is described using a novel anion exchange chromatographic resin called TEVA. Re and PGEs are converted into bromo complexes by heating with HF-HBr mixture in a Teflon bomb at 518 K, by in situ-generated Br2 formed by reaction of HBr and HNO3. Distribution coefficients (Kd) of the bromo complexes onto TEVA resin in 0.1 M HBr with heating at 353 K for one night were 2200, 16000, 1600, 5500, 4000, and 17 000 for Ru, Pd, Re, Os, Ir, and Pt, respectively, thus allowing 97% recovery of Re and PGEs in 5 mL of solution by 0.1 mL of resin. These strongly bound Re and PGE bromo complexes are stripped and recovered >90% by the following three steps: (i) addition of 6 M HCI at 353 K and 2.2 M HCI-5 M HBr at 353 K; (ii) heating the resin in 6 M HCI at 353 K to convert the bromo complexes into the chloro complexes with weaker affinities to the resin; and (iii) sequential addition of the HCI-HBr mixture at room temperature and 7 M HI. Neither the elution profile nor the recovery yield for a 0.2-g geological sample showed significant changes, indicating minimal matrix effects for the geological samples. Total blanks were <14 pg for Ru, Pd, and Pt and <10 pg for Re, Os, and Ir. This new technique, therefore, is suitable for simultaneous determination of subnanogram per gram of Ru, Pd, Re, Os, Ir, and Pt and Os isotope analysis in geological, mineralogical, and environmental samples without direct addition of toxic reagents required in distillation/extraction of Os or oxidizing of Ir.

DOI： 10.1021/ac010615u

Determination of total sulfur at microgram per gram levels in geological materials by oxidation of sulfur into sulfate with in situ generation of bromine using isotope dilution high-resolution ICPMS 査読

A. Makishima, E. Nakamura

Analytical Chemistry 73 ( 11 ) 2547 - 2553 2001年6月

担当区分：筆頭著者掲載種別：研究論文（学術雑誌）

We have developed a new, simple, and accurate method for the determination of total sulfur at microgram per gram levels in milligram-sized silicate materials with isotope dilution high-resolution inductively coupled plasma mass spectrometry equipped with a flow injection system. In this method, sulfur can be quantitatively oxidized by bromine into sulfate with achievement of isotope equilibrium between the sample and spike. Detection limits for 32S+ and 34S+ in the ideal solution and silicate samples were 1 and 6 ng mL-1 and 0.07 and 0.3 μg g-1, respectively. The total blank was 46 ng, so that a 40-mg silicate sample containing 10 μg g-1 sulfur can be measured with a blank correction of < 10%. This total blank can be lowered to 8 ng if a low-blank air system is used for evaporations. To evaluate the applicability of this method, we analyzed not only silicate reference materials with sulfur content of 5.25-489 μg g-1 and sample sizes of 13-40 mg but also the Allende meteorite with a sulfur content of 2%. The reproducibility for various rock types was <9%, even though blank corrections in some samples of low sulfur content were up to 24%. This method is suitable for analyzing geological samples as well environmental samples such as soils, sediments, and water samples.

DOI： 10.1021/ac001550i

Precise analysis of ²³⁴U/²³⁸U ratio using UO<inf>2</inf>⁺ ion with thermal ionization mass spectrometry for natural samples 査読

Tetsuya Yokoyama, Akio Makishima, Eizo Nakamura

Chemical Geology 181 ( 1-4 ) 1 - 12 2001年

掲載種別：研究論文（学術雑誌）

We have developed a new, highly precise method for U isotopic analysis using a thermal ionization mass spectrometry (TIMS) by measuring UO+2 ions emitted from a very small amount (100- 10 ng) of U. A new ionization activator, a silicic acid-diluted phosphoric acid solution, was found to be effective not only for producing a strong and stable UO+2 ion beam, but also for keeping the mass fractionation during measurement small and constant. U isotope analysis was carried out by a "dynamic multi collection" method using three Faraday cup collectors and a secondary electron multiplier in ion counting mode with RPQ (RPQ-SEM). For precise isotope analysis, baselines of the Faraday cups and a conversion factor between Faraday cups and the RPQ-SEM were precisely determined simultaneously with U isotope collection. Analytical precision and reproducibility of 234U/238U ratio ranged from 0.10% to 0.38% (2σmean) and from 0.13% to 0.31% (2σ), respectively, for 100-10 ng of U extracted from a natural rhyolitic obsidian. The precision and reproducibility were improved compared with previous studies, and thus, our method is especially useful for samples with very low abundance of U. © 2001 Elsevier Science B. V. All rights reserved.

DOI： 10.1016/S0009-2541(01)00270-4

Evaluation of the coprecipitation of incompatible trace elements with fluoride during silicate rock dissolution by acid digestion 査読

Tetsuya Yokoyama, Akio Makishima, Eizo Nakamura

Chemical Geology 157 ( 3-4 ) 175 - 187 1999年5月

掲載種別：研究論文（学術雑誌）

Insoluble fluoride precipitates which form during HF digestion of mafic silicate rocks coprecipitate in their structures the trace elements such as Rb, Sr, Y, Cs, Ba, REE, Pb, Th and U, thus hindering their accurate determination. We have estimated quantitatively the coprecipitation of trace elements into such fluorides, and suggest an effective method of digestion that can suppress completely fluoride precipitation. Conventional acid digestion of three samples of mafic and ultramafic silicate rocks resulted in the precipitation of sticky material and very poor yields of certain trace element in the resultant solution. XRD analysis indicated that the precipitates were composed of fluorides such as CaAlF5, CaMg2Al2F12, Na0.88Mg0.88Al1.12(F,OH)6 · H2O and MgF2, the formation of which depended on the major element composition of the rock sample. Coprecipitation of trace elements appeared to be strongly controlled by both ionic radius and valency of the elements as well as the species of the host fluoride precipitate, resulting in selective losses of the elements into these fluorides. On the other hand, almost 100% of the trace elements were recovered using larger amounts of HCIO4 than is conventionally used and evaporating the sample to dryness in a step-wise fashion. Using this method, white precipitates were formed as oxides of high field strength elements after decomposition of the sample. Coprecipitation of trace elements of interest in this study with the oxides is negligible except for Th for which 0.5-3.2% by weight was coprecipitated probably as the insoluble oxide. As our method also results in negligible blank values, it can be used for both the accurate determination of trace element using ICP-MS as well as isotope analysis using TIMS.

DOI： 10.1016/S0009-2541(98)00206-X

Determination of zirconium, niobium, hafnium and tantalum at ng g ^-1 levels in geological materials by direct nebulisation of sample HF solution into FI-ICP-MS 査読

Akio Makishima, Eizo Nakamura, Toshio Nakano

Geostandards Newsletter 23 ( 1 ) 7 - 20 1999年

担当区分：筆頭著者掲載種別：研究論文（学術雑誌）

We have developed a rapid and accurate method to determine Zr, Nb, Hf and Ta (denoted as HFSE) in geological samples by inductively coupled plasma-mass spectrometry fitted with a flow injection system (FI-ICP-MS). The method involves sample decomposition by HF followed by HF dissolution of HFSE coprecipitated with insoluble Mg and Ca fluoride residues formed during the initial HF attack. This HF solution was directly nebulized into an ICP mass spectrometer. An external calibration curve method and an isotope dilution method (ID) were applied for the determination of Nb and Ta, and of Zr and Hf, respectively. Recovery yields of HFSE were, 96% for peridotite, basalt and andesite compositions, apart from Zr and Hf for peridotite (> 85%). No matrix effects for either signal intensities of HFSE or isotope ratios of Zr and Hf were observed in basalt, andesite and peridotite solutions down to a dilution factor of 100. Detection limits in silicate rocks were 40, 2, 1 and 0.1 ng g-1 for Zr, Nb, Hf and Ta, respectively. This technique required only 0.1 ml of sample solution, and thus is suitable for analysing small and/or precious samples such as meteorites, mantle peridotites and their mineral separates. We also present newly determined data for the Zr, Nb, Hf and Ta concentrations in USGS silicate reference materials DTS-1, PCC-1, BCR-1, BHVO-1 and AGV-1, GSJ reference materials JB-1, -2, -3, JA-1, -2 and -3, and the Smithsonian reference Allende powder.

DOI： 10.1111/j.1751-908X.1999.tb00555.x

Determination of Boron in Silicate Samples by Direct Aspiration of Sample HF Solutions into ICPMS 査読

Akio Makishima, Eizo Nakamura, Toshio Nakano

Analytical Chemistry 69 ( 18 ) 3754 - 3759 1997年9月

担当区分：筆頭著者掲載種別：研究論文（学術雑誌）

A rapid and precise technique for the determination of boron content in silicate rocks was developed by employing isotope dilution inductively coupled plasma mass spectrometry with a flow injection system (FI-ID-ICPMS). The sample was decomposed with HF and mannitol, dried to remove silicon as gas, and redissolved with HF to extract boron from the fluoride residue. Ultimately, the HF solution was directly aspirated into the ICPMS. The total procedural blank was 0.08-0.36 ng. No matrix-induced mass discrimination was observed in the rock solution for dilution factors of up to 110. The present method is capable of determining 1 μg g-1 boron in a 1 mg silicate rock sample with blank correction of <20%. Replicate analyses of USGS rock standards, PCC-1, BCR-1, and AGV-1, and GSJ rock standards, JB-1, JB-2, JB-3, JA-1, JA-2, and JA-3, yielded reproducibilities (RSD) of <2%. These results were identical with those obtained by ID thermal ionization mass spectrometry within the analytical errors. These results indicate that the present method allows the precise determination of the boron content in a small sample of silicate materials with simple handling, resulting in the extremely low procedural blank of boron.

DOI： 10.1021/ac970383s

Ce isotope ratios of N-type MORB 査読

Akio Makishima, Akimasa Masuda

Chemical Geology 118 ( 1-4 ) 1 - 8 1994年12月

担当区分：筆頭著者掲載種別：研究論文（学術雑誌）

Isotope ratios of Ce, Nd and Sr, and light rare-earth elements (La, Ce, Nd and Sm) concentrations were measured for sixteen N-type MORB samples from DSDP Sites 420, 421, 429, 597B and 597C (East Pacific Rise), 504B (Costa Rica Rift), and 395, 519A, 522B, 562 and 564 (Mid Atlantic Ridge). All the samples were confirmed as N-type MORB based on Nd and Sr isotope ratios, and LREE patterns. The Ce isotope ratios ranged from 0.0225616 (ε{lunate}Ce = - 1.6) to 0.0225633 (ε{lunate}Ce = - 1.0). Averages of ε{lunate}Ce and ε{lunate}Nd of N-type MORB were - 1.4 and 9.5, respectively. The average of ε{lunate}Ce is quite different from previous estimates. We propose that ε{lunate}Ce = - 1.4 should be used as the typical MORB Ce isotope ratio in future studies. © 1994.

DOI： 10.1016/0009-2541(94)90166-X

ジルコンをめぐる最近の話題-3-ジルコンの希土類元素地球化学査読

牧嶋昭夫, 中村栄三

岩鉱 89 ( 1 ) p1 - 14 1994年1月

Search for p-isotopic anomaly of cerium in the bulk Allende meteorite 査読

Akio Makishima, Akimasa Masuda

GEOCHEMICAL JOURNAL 28 ( 2 ) 115 - 122 1994年

担当区分：筆頭著者掲載種別：研究論文（学術雑誌）

LREE (La, Ce, Nd and Sm) concentrations, and 143Nd/144Nd and 138Ce/142Ce ratios of two powder aliquots from the bulk Allende meteorite (BAM) were measured to investigate p-isotopic anomalies of Ce. Initial Ce isotope ratios of the two aliquots were calculated assuming an age of 4.56 Ga, identical with ages of other chondrites or eucrites. From the data, we conclude that there are no recognizable p-isotopic anomalies in BAM. This suggests that the existence of p-isotopic anomalies of other REE in BAM is unlikely. Our data can not, however, rule out the possibility that this is only caused by averaging of heterogeneous distribution of p-isotopic anomalies. © 1994, GEOCHEMICAL SOCIETY OF JAPAN. All rights reserved.

DOI： 10.2343/geochemj.28.115

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