首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 468 毫秒
1.
We present a new procedure for the separation and purification of Cu and Zn from geological samples. Our procedure employed a single pass, triple‐stack column set‐up. The first column, filled with TRU resin (TrisKem International), quantitatively removed Fe and Ti from sample matrices. A second column, filled with pre‐filter resin (TrisKem International), removed organic compounds. Finally, a third column, filled with anion exchange resin (AG1‐X8, 200–400 mesh, Bio‐Rad), was used to separate Cu and Zn from the remaining matrix. Our procedure required about 50% less acid volume than previously reported methods for Cu and Zn separation, thereby minimising analytical blanks and column running times. Copper and Zn stable isotope ratios were determined by a Thermo Neptune Plus MC‐ICP‐MS using Zn and Cu external normalisation, respectively, in addition to sample‐standard bracketing to correct for instrumental mass bias. We explore the inter‐calibration of Cu and Zn isotope fractionation coefficients during analysis by measuring mixed Cu–Zn solutions with enhanced mass bias variation generated by varying sample gas flow rates. Our results demonstrate that this procedure is useful when variation in instrumental mass bias throughout analytical sequences is insufficient to inter‐calibrate Cu and Zn fractionation coefficients.  相似文献   

2.
Chromium (Cr) isotopes have been widely used in various fields of Earth and planetary sciences. However, high‐precision measurements of Cr stable isotope ratios are still challenged by difficulties in purifying Cr and organic matter interference from resin using double‐spike thermal ionisation mass spectrometry. In this study, an improved and easily operated two‐column chemical separation procedure using AG50W‐X12 (200–400 mesh) resin is introduced. This resin has a higher cross‐linking density than AG50W‐X8, and this higher density generates better separation efficiency and higher saturation. Organic matter from the resin is a common cause of inhibition of the emission of Cr during analysis by TIMS. Here, perchloric and nitric acids were utilised to eliminate organic matter interference. The Cr isotope ratios of samples with lower Cr contents could be measured precisely by TIMS. The long‐term intermediate measurement precision of δ53/52CrNIST SRM 979 for BHVO‐2 is better than ± 0.031‰ (2s) over one year. Replicated digestions and measurements of geological reference materials (OKUM, MUH‐1, JP‐1, BHVO‐1, BHVO‐2, AGV‐2 and GSP‐2) yield δ53/52CrNIST SRM 979 results ranging from ?0.129‰ to ?0.032‰. The Cr isotope ratios of geological reference materials are consistent with the δ53/52CrNIST SRM 979 values reported by previous studies, and the measurement uncertainty (± 0.031‰, 2s) is significantly improved.  相似文献   

3.
We report an improved procedure for the determination of the platinum‐group elements (PGE) and Re, and Os isotopes from a single sample aliquot by isotope dilution (ID) using inductively coupled plasma‐mass spectrometry (ICP‐MS) and negative thermal ionisation mass spectrometry (N‐TIMS), respectively. A two‐stage column method was used to purify PGE‐Re from their sample matrix and interfering elements (e.g., Mo, Zr and Hf) after Os had been separated by CCl4 solvent extraction. The first column separation step used cation exchange resin (AG50W‐X8) to concentrate PGE‐Re and some potential interfering elements (e.g., Mo, Zr and Hf). In the second step, N‐benzoyl‐N‐phenylhydroxylamine (BPHA) extraction resin was used to separate PGE‐Re from the remaining interfering elements, which all remained strongly absorbed to the resin. The method was used to determine the PGE and rhenium, and Os isotope ratios in a range of geochemical reference materials (TDB‐1, WGB‐1, BHVO‐2 and UB‐N). The obtained results agree well with those previously published. This new method enables PGE‐Re abundances and Os isotopic ratios to be determined on the same sample digestion, and circumvents the problems created by sample heterogeneity when comparing PGE and Re‐Os isotope data.  相似文献   

4.
We present the first technique to obtain precise and accurate vanadium (V) stable isotope compositions by chemical isolation and multi‐collector inductively coupled plasma‐mass spectrometry (MC‐ICP‐MS). Separation of V from matrix elements was achieved via five separate ion exchange columns. The procedure quantitatively removed Ti and Cr, which contain direct isobaric interferences on the minor isotope 50V. Isotope compositions were determined using a conventional standard solution‐sample bracketing technique. The V isotope composition for an in‐house secondary standard solution from BDH Chemicals was δ51V = ?1.19 ± 0.12‰ (2s, n = 600), measured as the per mil deviation relative to the composition of a widely available Specpure Alfa Aesar (AA) vanadium solution. This represents an improvement in measurement precision on previous techniques of almost two orders of magnitude. The effects of adding Cr, Ti and S to standard solutions were explored to determine the robustness of protocols. Only very low levels of these elements could be tolerated to obtain precise and accurate isotope compositions and was achieved with the chemical purification procedure. Standard solutions from AA and BDH processed as unknowns through the entire chemical separation and measurement protocols returned 100% yields and the same isotopic compositions as those of unprocessed standard solutions.  相似文献   

5.
Lithium separation technique for three reference materials has been established together with precise determination of lithium isotope using a Neptune multi collector-inductively coupled plasma mass spectrometry (MC-ICP-MS). The solutions of lithium element standard reference materials, potassium, calcium, sodium, magnesium and iron single element, were used to evaluate analytical methods applied. Three separate stages of ion-exchange chromatography were carried out using organic cation-exchange resin (AG 50W-X8). Lithium was enriched for the three stages using different eluants, which are 2.8 M HCl, 0.15 M HCl and 0.5 M HCl in 30% ethanol, respectively. The columns for the first and second stages are made of polypropylene, and those for the third stage are made of quartz. Total reagent volume for the entire chemical process was 35 mL for three reference materials. The recovery yielded for the three stages is 98.9–101.2% with an average of 100.0%, 97.6–101.9% with an average of 99.9%, and 99.8–103.3% with an average of 100.6%, respectively. The precision of this technique is conservatively estimated to be ±0.72–1.04‰ (2σ population), which is similar to the precision obtained by different authors in different laboratories with MC-ICP-MS. The δ7Li values (7Li/6Li relative to the IRMM-016 standard) determined for andesite (AGV-2) and basalt (BHVO-2) are 5.68‰ (n=18), 4.33‰ (n=18), respectively. The δ7Li value (7Li/6Li relative to the L-SVEC standard) determined for IRMM-016 is –0.01‰ (n=15). All these analytical results are in good agreement with those previously reported. In addition, the results for the same kinds of samples analyzed at the MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, are consistent with those obtained at the Plasma Laboratory, University of Maryland, within analytical uncertainty. According to these experiment results, it is concluded that this proposed procedure is a suitable method for determining the lithium isotopic composition of natural samples.  相似文献   

6.
We present a new column chemistry technique for the quantitative separation of heavy lanthanoids by an ultra‐fine‐grained LN resin (20–50 µm) with a specific emphasis on the purification of Er and Yb for their isotopic analysis. To achieve the quantitative separation of Er and Yb within a reasonable timescale, flash column chromatography was applied, where the column was attached to a newly designed vacuum box system, thus accelerating the elution speed by ten times compared with that of the normal column procedure operated by gravity flow. The recovery yields of Er and Yb were confirmed to be approximately 100%, which is important to suppress the effect of the mass‐independent fractionation of the Er and Yb isotopes during chromatography. Additionally, we have developed precise Er and Yb isotope measurements by thermal ionisation mass spectrometry (TIMS) using multistatic and/or dynamic methods. Moreover, in most cases, the Er and Yb isotope compositions of the measured four terrestrial rock samples were indistinguishable from those of the commercially available Er and Yb Alfa Aesar solutions. The new method presented in this work will be useful for future studies on heavy lanthanoids in various geological materials.  相似文献   

7.
The interest in the study of gallium (Ga) stable isotope fractionation in low‐ and high‐temperature environments has increased significantly in the last few years. However, a unified reference material (RM) is still lacking for the Ga isotope research community, which hinders interlaboratory comparison between different groups. Consequently, certification of Ga isotopic reference materials for interlaboratory comparison is of high priority. In this study, Ga isotope ratio data for ten geological RMs including silicates, shales and ferromanganese nodules, and two pure Ga RMs including NIST SRM 994 and NIST SRM 3119a reported by three different groups, were determined by MC‐ICP‐MS. Sample matrices of geological RMs were separated by a two‐column separation method with the use of AG MP‐1M and AG 50‐X8 resin, separately, and quantitative recoveries of > 99% Ga were obtained for all geological RMs. Instrumental mass bias was corrected by the combined calibrator‐sample bracketing and internal normalisation model. Validation of the proposed method was performed by analysing synthetic solutions. After normalisation of all available δ71Ga data of geological RMs to a single Ga RM, results obtained in our study are in agreement with previously reported results.  相似文献   

8.
AG MP-1阴离子交换树脂元素分离方法再研究   总被引：2，自引：0，他引：2  
目前不同实验室建立的用于MC-ICP-MS铜铁锌同位素测定的离子交换分离方法多适用于一般地质样品的Fe同位素高精度测定,而对于一些类似于白云鄂博Fe-Nb-REE矿床的特殊地质样品,这些分离方法的适用情况有待进一步研究。为研究REE、Nb、Ta、Co、Cu、W等元素是否能够和Fe有效分离,采用AG MP-1阴离子交换树脂,依次以6 mol/L HCl和2 mol/L HCl为介质对这些元素进行淋洗,并利用ICP-AES和ICP MS对淋洗液中的各元素含量进行测定。实验结果表明,在6 mol/L HCl介质条件下,运用AG MP-1树脂可以将REE、W与Fe有效地分离,能够将Nb、Ta的含量降低一个数量级;Fe、Co、Cu的淋洗行为和前人研究结果一致。  相似文献   

9.
Magnesium Isotope Compositions of Natural Reference Materials   总被引：1，自引：0，他引：1  
This study presents a chemical protocol for the separation of Mg that is particularly adapted to alkali‐rich samples (granite, soil, plants). This protocol was based on a combination of two pre‐existing methods: transition metals were first removed from the sample using an AG‐MP1 anion‐exchange resin, followed by the separation of alkalis (Na, K) and bivalent cations (Ca2+, Mn2+ and Sr2+) using a AG50W‐X12 cation‐exchange resin. This procedure allowed Mg recovery of ～ 10 0 ± 8%. The [Σcations]/[Mg] molar ratios in all of the final Mg fractions were lower than 0.05. The Mg isotope ratios of eleven reference materials were analysed using two different MC‐ICP‐MS instruments (Isoprobe and Nu Plasma). The long‐term reproducibility, assessed by repeated measurements of Mg standard solutions and natural reference materials, was 0.14‰. The basalt (BE‐N), limestone (Cal‐S) and seawater (BCR‐403) reference materials analysed in this study yielded δ26Mg mean values of ?0.28 ± 0.08‰, ?4.37 ± 0.11‰ and ?0.89 ± 0.10‰ respectively, in agreement with published data. The two continental rocks analysed, diorite (DR‐N) and granite (GA), yielded δ26Mg mean values of ?0.50 ± 0.08‰ and ?0.75 ± 0.14‰, respectively. The weathering products, soil (TILL‐1) and river water (NIST SRM 1640), gave δ26Mg values of ?0.40 ± 0.07‰ and ?1.27 ± 0.14‰, respectively. We also present, for the first time, the Mg isotope composition of bulk plant and organic matter. Rye flour (BCR‐381), sea lettuce (Ulva lactuva) (BCR‐279), natural hairgrass (Deschampsia flexuosa) and lichen (BCR‐482) reference materials gave δ26Mg values of ?1.10 ± 0.14‰, ?0.90 ± 0.19‰, ?0.50 ± 0.22‰ and ?1.15 ± 0.27‰ respectively. Plant δ26Mg values fell within the range defined by published data for chlorophylls.  相似文献   

10.
采用AGMP-1阴离子交换树脂，分别以7mol／L HCl、2mol／L HCl、0．5mol／L HNO3作为淋洗剂，可有效分离Cu、Fe、Zn。介绍了方法的基本原理、化学分离过程及混合标准溶液与地质标样的分离结果。结果表明，Cu、Fe、Zn回收率均接近100％，标准溶液在离子交换分离前后同位素组成一致，可以满足多接收器等离子体质谱对Cu、Fe、Zn同位素高精度分析的要求。  相似文献   

11.
对不同离子交换柱、淋洗体积、盐度、分离次数等一系列影响铜、锌纯化分离效果的条件进行了探讨,确定了环境样品(湖泊沉积物、植物和颗粒物)中铜、锌同位素测定时化学分离的最佳条件。采用AGMP-1(100～200目)阴离子交换树脂,以7mol/LHCl+0.001%H2O2、2mol/LHCl+0.001%H2O2、0.5mol/LHNO3作为淋洗液,分别在适当的体积接收淋洗液,可以有效地分离沉积物、植物和悬浮物等样品中的铜和锌。化学分离过程中Cu和Zn的回收率接近100%,同位素分馏在测试误差范围以内。将此方法应用于对红枫湖和阿哈湖水体悬浮物、植物和鱼类等样品中Cu、Zn的分离,经MC-ICP-MS测试后,准确获得了这些样品的Cu、Zn同位素组成。  相似文献   

12.
Isotope ratios of heavy elements vary on the 1/10000 level in high temperature materials, providing a fingerprint of the processes behind their origin. Ensuring that the measured isotope ratio is precise and accurate depends on employing an efficient chemical purification technique and optimised analytical protocols. Exploiting the disparate speciation of Cu, Fe and Zn in HCl and HNO3, an anion exchange chromatography procedure using AG1‐×8 (200–400 mesh) and 0.4 × 7 cm Teflon columns was developed to separate them from each other and matrix elements in felsic rocks, basalts, peridotites and meteorites. It required only one pass through the resin to produce a quantitative and pure isolate, minimising preparation time, reagent consumption and total analytical blanks. A ThermoFinnigan Neptune Plus MC‐ICP‐MS with calibrator‐sample bracketing and an external element spike was used to correct for mass bias. Nickel was the external element in Cu and Fe measurements, while Cu corrected Zn isotopes. These corrections were made assuming that the mass bias for the spike and analyte element was identical, and it is shown that this did not introduce any artificial bias. Measurement reproducibilities were ± 0.03‰, ± 0.04‰ and ± 0.06‰ (2s) for δ57Fe, δ65Cu and δ66Zn, respectively.  相似文献   

13.
利用多接收电感耦合等离子体质谱仪测定Mg同位素比值时,样品溶液中的基质元素可影响Mg同位素比值的准确测定。根据白云鄂博样品富含REE、Nb、Fe(REE质量分数可达10%、Nb质量分数可达0.1%)等元素的特性,本研究在评估测试溶液中Nd(REE)、Mn元素质量比对Mg同位素比值影响的基础上,建立了适用于富含REE、Nb、Fe等元素的特殊样品中Mg同位素的化学纯化方法。研究表明,当m（Nd）/m（Mg）>0.2、m（Mn）/m（Mg）>0.2时,REE和Mn的存在明显影响Mg同位素测定值的准确性,应予以去除。所建纯化方法首先是利用AG MP-1阴离子交换树脂,以10 mol/L HCl+0.001% H2O2溶液为上样介质和淋洗液,接取前2.5 mL淋洗液,去除样品中 Fe、Mn等杂质元素;然后利用AG50W-X12阳离子交换树脂,以2 mol/L HCl为上样介质和淋洗液,去除REE、Nb等杂质元素。所建方法满足多接收器等离子体质谱进行高REE-Nb-Fe-Mn样品中Mg同位素测定的要求。  相似文献   

14.
Secondary ion mass spectrometry (SIMS) requires matrix‐matched reference materials to calibrate mass fractionation during oxygen isotope measurement. Over one thousand SIMS oxygen isotope measurements were conducted on eleven natural mineral samples (five olivines, three clinopyroxenes and three orthopyroxenes) in nineteen sessions using CAMECA IMS 1280 SIMS instruments to evaluate their potential as SIMS reference materials. The obtained results reveal oxygen isotope homogeneity of these samples. No matrix effect was measured for the same variety of mineral samples with limited Mg‐number variations (89.6–94.2, 90–91.9 and 90.1–92.1 for olivine, clinopyroxene and orthopyroxene, respectively). The recommended oxygen isotope compositions of these samples were determined using laser fluorination. These samples are therefore suitable to be used as reference materials for in situ oxygen isotope microanalysis.  相似文献   

15.
This study presents a high‐precision method to measure barium (Ba) isotope compositions of international carbonate reference materials and natural carbonates. Barium was purified using chromatographic columns filled with cation exchange resin (AG50W‐X12, 200–400 mesh). Barium isotopes were measured by MC‐ICP‐MS, using a 135Ba–136Ba double‐spike to correct mass‐dependent fractionation during purification and instrumental measurement. The precision and accuracy were monitored by measuring Ba isotope compositions of the reference material JCp‐1 (coral) and a synthetic solution obtained by mixing NIST SRM 3104a with other matrix elements. The mean δ137/134Ba values of JCp‐1 and the synthetic solution relative to NIST SRM 3104a were 0.21 ± 0.03‰ (2s, n = 16) and 0.02 ± 0.03‰ (2s, n = 6), respectively. Replicate measurements of NIST SRM 915b, COQ‐1, natural coral and stalagmite samples gave average δ137/134Ba values of 0.10 ± 0.04‰ (2s, n = 18), 0.08 ± 0.04‰ (2s, n = 20), 0.27 ± 0.04‰ (2s, n = 16) and 0.04 ± 0.03‰ (2s, n = 20), respectively. Barium mass fractions and Ba isotopes of subsamples drilled from one stalagmite profile were also measured. Although Ba mass fractions varied significantly along the profile, Ba isotope signatures were homogeneous, indicating that Ba isotope compositions of stalagmites could be a potential tool (in addition to Ba mass fractions) to constrain the source of Ba in carbonate rocks and minerals.  相似文献   

16.
Rare earth data for nine well-known geochemical reference samples were obtained using a rapid and efficient cation exchange chromatographic separation procedure. It involves the use of a mixed-acid eluent (HCI and HNO3) on a 15 x 1 cm column of Bio-Rad AG50–X8 (200–400 mesh) to remove matrix and many trace elements from rock solutions. The rare earth elements are removed from the column using 60 ml 7M HNO3. The pre-concentration procedure described is routinely used in this laboratory for the determination of the rare earth elements by mass spectrometry-isotope dilution, and has been satisfactorily used for their determination using inductively-coupled plasma-source atomic emission spectrometry.  相似文献   

17.
AG MP-1M阴离子分离Cu、Fe、Zn及其在Fe同位素测定上的应用   总被引：1，自引：0，他引：1  
采用新型阴离子交换树脂AG MP-1M,分别以8.2 mol/L HCl+0.01%HF、4 mol/L HCl、2 mol/L HCI和0.5 mol/L HNO,可以有效分离地质样品中Cu、Co、Fe和Zn,克服了AG MP-1阴离子交换树脂分离Cu时Co随Cu同时淋洗下来,以及在分离Co含量较高的地质样品时Co和Cu需过二次柱分离的弊端.对花岗闪长岩等地质标样的研究结果表明,AG MP-1M阴离子交换树脂能有效分离Cu、Fe和Zn,并且它们的回收率均大于99%.标准样品经过离子交换分离后Fe同位素未发生分馏,可满足多接收器电感耦合等离子体质谱(MC-ICPMS)的同位素测定要求.  相似文献   

18.
Here we describe high‐precision molybdenum isotopic composition measurements of geological reference materials, performed using multi‐collector inductively coupled plasma‐mass spectrometry (MC‐ICP‐MS). Purification of Mo for isotopic measurements was achieved by ion exchange chromatography using Bio‐Rad AG® 1‐X8 anion exchange resin. Instrumental mass bias was corrected using 100Mo‐97Mo double spiking techniques. The precision under intermediate measurement conditions (eighteen measurement sessions over 20 months) in terms of δ98/95Mo was 0.10‰ (2s). The measurement output was approximately four times more efficient than previous techniques, with no compromise in precision. The Mo isotopic compositions of seven geochemical reference materials, seawater (IAPSO), manganese nodules (NOD‐P‐1 and NOD‐A‐1), copper‐molybdenum ore (HV‐2), basalt (BCR‐2) and shale (SGR‐1b and SCo‐1), were measured. δ98/95Mo values were obtained for IAPSO (2.25 ± 0.09‰), NOD‐P‐1 (?0.66 ± 0.05‰), NOD‐A‐1 (?0.48 ± 0.05‰), HV‐2 (?0.23 ± 0.10‰), BCR‐2 (0.21 ± 0.07‰), SCo‐1 (?0.24 ± 0.06‰) and SGR‐1b (0.63 ± 0.02‰) by calculating δ98/95Mo relative to NIST SRM 3134 (0.25‰, 2s). The molybdenum isotopic compositions of IAPSO, NOD‐A‐1 and NOD‐P‐1 obtained in this study are within error of the compositions reported previously. Molybdenum isotopic compositions for BCR‐2, SCo‐1 and SGR‐1b are reported for the first time.  相似文献   

19.
Nickel in the six SA primary (NIMROCS) and fourteen secondary reference materials as well as in a phosphate rock has been determined accurately by means of atomic absorption spectrometry. A selective and quantitative twocolumn ion exchange separation procedure, using AG50W-X4 cation exchange resin, is employed for the separation of nickel from all other elements. The accuracy and precision of the described method are demonstrated by the analysis of synthetic rock solutions containing various amounts of nickel.  相似文献   

20.
利用新型阴离子交换树脂分离沉积物中的重金属Pb,采用表面热电离质谱法(TIMS)测定了沉积物样品中的Pb同位素组成。新型树脂为大孔径阴离子树脂AG-MP-1M,淋洗液采用低浓度的盐酸,避免了使用难以纯化的氢溴酸,可有效地降低试剂空白。通过对铅同位素标准物质NIST NBS-981的重复测试,方法的精密度(<0.5%,2s)和准确度均达到了应用研究的要求。对5个实际沉积物样品中的铅同位素组成进行测定,获得了理想的分析效果。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号