Direct determination of δ44/42Ca isotope ratio by ion chromatography/low‐resolution multicollector ICPMS

High‐precision on‐line procedure for measurement of calcium isotopic ratio by coupling ion chromatography to multicollector inductively coupled plasma mass spectrometry was developed. Calcium separation from the sample matrix was achieved on an ion chromatography column—IonPac CS16—ID 3 mm connected with CERS 500 2 mm suppressor and followed by multicollector inductively coupled plasma mass spectrometry calcium isotopic ratio determination. Dry plasma mode was used with Aridus II desolvation system. To sustained samples with high level of total dissolved salts as well as account capacity of applied analytical column, the method has been optimized regarding calcium isotope ratio measurements with low‐resolution mass spectrometry. Mass discrimination and instrument drift were corrected by sample‐standard bracketing method using the ⁴⁴Ca/⁴²Ca isotope ratio of SRM 915a as a standard. Good accuracy and reasonable precision of calcium isotope ratio (generally 0.20‰ [2SD]) were achieved, which are comparable to off‐line Ca separation and continuous measurement. The reproducibility of the proposed analytical procedure was verified by measuring the SRM 915a standard as a sample randomly over 3 months (n = 56). Applicability of the protocol was demonstrated for matrix‐rich natural water samples, coral samples, and bone standard reference materials.     

New methodical and instrumental developments in laser ablation inductively coupled plasma mass spectrometry

Many tasks in bulk analysis, micro analysis and depth profile analysis can be solved advantageously by laser ablation inductively coupled plasma mass spectrometry (Laser ICP-MS) in particular, when both the chemical and elemental distributions in the sample are to be determined. However, the analyst has to take into account that the analytical precision and accuracy of the Laser ICP-MS is influenced decisively by signal standardization, the homogeneity of the samples as well as calibration standards and the mass-spectrometric measuring mode, which is usually sequential when performed with scanning mass spectrometers such as quadrupol- or sector-based instruments. Using the ablated mass as standard, an excellent level of the analytical precision and accuracy (relative standard deviation R.S.D.<0.5%) has been obtained for homogeneous sample materials such as alloys. For inhomogeneous samples, such as pressed pellets, a statistical test is described, which is based upon the auto-correlation function to characterize the sample inhomogeneity. The application of the test allows us to calculate the representative mass for the quantitative analysis at previously defined analytical precision. In the instrumental part of the paper a new type of an ICP—time-of-flight (TOF) mass spectrometer—is described, constructed and built up in our laboratory. For fast signal counting an application-specific integrated circuit (ASIC) was developed, which permits a time resolution of 1 ns. The analytical performance of the TOF when used in combination with an ICP is demonstrated in terms of resolution, ion extraction rate, detection limits and dynamic range. The determination of ³⁹K⁺ and ⁴⁰Ca⁺ at trace level can be realized in a cool plasma condition (high central gas flow) only with a small interference by ⁴⁰Ar⁺. Detection limits of 23 elements were measured with typical values in the lower nanograms per liter range. The ion extraction rates, measured for a sample mass of 1 ng in terms of counts per second divided by the relative isotope abundance, are one order of magnitude higher than those obtained with a quadrupol-based instrument.     

Trace analysis of high-purity graphite by LA-ICP-MS

Laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been established as a very efficient and sensitive technique for the direct analysis of solids. In this work the capability of LA-ICP-MS was investigated for determination of trace elements in high-purity graphite. Synthetic laboratory standards with a graphite matrix were prepared for the purpose of quantifying the analytical results. Doped trace elements, concentration 0.5 microg g(-1), in a laboratory standard were determined with an accuracy of 1% to +/- 7% and a relative standard deviation (RSD) of 2-13%. Solution-based calibration was also used for quantitative analysis of high-purity graphite. It was found that such calibration led to analytical results for trace-element determination in graphite with accuracy similar to that obtained by use of synthetic laboratory standards for quantification of analytical results. Results from quantitative determination of trace impurities in a real reactor-graphite sample, using both quantification approaches, were in good agreement. Detection limits for all elements of interest were determined in the low ng g(-1) concentration range. Improvement of detection limits by a factor of 10 was achieved for analyses of high-purity graphite with LA-ICP-MS under wet plasma conditions, because the lower background signal and increased element sensitivity.     

Investigation on elemental and isotopic fractionation during 196 nm femtosecond laser ablation multiple collector inductively coupled plasma mass spectrometry

Despite the large number of successful applications of laser ablation, elemental and isotopic fractionation coupled to inductively coupled plasma mass spectrometry (ICP-MS) remain as the main limitations for many applications of this technique in the fields of analytical chemistry and Earth Sciences. A substantial effort has been made to control such fractionations, which are well-established features of nanosecond laser ablation systems. Technological advancements made over the past decade now allow the ablation of solids by femtosecond laser pulses in the deep ultraviolet (UV) region at wavelengths less than 200 nm. Here the use of femtosecond laser ablation and its effects on elemental and isotopic fractionation is investigated. The Pb/U system is used to illustrate elemental fractionation and stable Fe isotopes are used to illustrate isotopic fractionation. No elemental fractionation is observed beyond the precision of the multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) measurements. Without a matrix match between standard and sample, elemental fractionation is absent even when using different laser ablation protocols for standardization and samples (spot versus raster). Furthermore, we found that laser ablation-induced isotope ratio drifts, commonly observed during nanosecond laser ablation, are undetectable during ultraviolet femtosecond laser ablation. So far the precision obtained for Fe isotope ratio determinations is 0.1‰ (2 standard deviation) for the ⁵⁶Fe/⁵⁴Fe ratio. This is close to that obtainable by solution multiple-collector inductively coupled plasma mass spectrometry. The accuracy of the results appears to be independent of the matrix used for standardization. The resulting smaller particle sizes reduce fractionation processes. Femtosecond laser ablation carries the potential to solve some of the difficulties encountered during the two prior decades since the introduction of laser ablation.     

Inorganic trace analysis by mass spectrometry

Mass spectrometric methods for the trace analysis of inorganic materials with their ability to provide a very sensitive multielemental analysis have been established for the determination of trace and ultratrace elements in high-purity materials (metals, semiconductors and insulators), in different technical samples (e.g. alloys, pure chemicals, ceramics, thin films, ion-implanted semiconductors), in environmental samples (waters, soils, biological and medical materials) and geological samples. Whereas such techniques as spark source mass spectrometry (SSMS), laser ionization mass spectrometry (LIMS), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), glow discharge mass spectrometry (GDMS), secondary ion mass spectrometry (SIMS) and inductively coupled plasma mass spectrometry (ICP-MS) have multielemental capability, other methods such as thermal ionization mass spectrometry (TIMS), accelerator mass spectrometry (AMS) and resonance ionization mass spectrometry (RIMS) have been used for sensitive mono- or oligoelemental ultratrace analysis (and precise determination of isotopic ratios) in solid samples. The limits of detection for chemical elements using these mass spectrometric techniques are in the low ng g⁻¹ concentration range. The quantification of the analytical results of mass spectrometric methods is sometimes difficult due to a lack of matrix-fitted multielement standard reference materials (SRMs) for many solid samples. Therefore, owing to the simple quantification procedure of the aqueous solution, inductively coupled plasma mass spectrometry (ICP-MS) is being increasingly used for the characterization of solid samples after sample dissolution. ICP-MS is often combined with special sample introduction equipment (e.g. flow injection, hydride generation, high performance liquid chromatography (HPLC) or electrothermal vaporization) or an off-line matrix separation and enrichment of trace impurities (especially for characterization of high-purity materials and environmental samples) is used in order to improve the detection limits of trace elements. Furthermore, the determination of chemical elements in the trace and ultratrace concentration range is often difficult and can be disturbed through mass interferences of analyte ions by molecular ions at the same nominal mass. By applying double-focusing sector field mass spectrometry at the required mass resolution—by the mass spectrometric separation of molecular ions from the analyte ions—it is often possible to overcome these interference problems. Commercial instrumental equipment, the capability (detection limits, accuracy, precision) and the analytical application fields of mass spectrometric methods for the determination of trace and ultratrace elements and for surface analysis are discussed.     

The determination of lead in blood using isotope dilution inductively coupled plasma mass spectrometry

Isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) was applied to the certification of Pb in four levels of NIST blood SRM, 955a. This standard reference material (SRM) represents a significant improvement over the previous blood reference material and will greatly aid method development. The lowest level, 47.76 ng/g Pb was determined with analysis uncertainty (95% CI, ID-ICP-MS uncertainties) of less than 1% and the highest level, 517.9 ng/g Pb to 0.3%. Uncertainty in the lowest level was due to sample inhomogeneity and variability in the analytical blank as the RSD on ratio measurements was typically better than 0.2%. Properly applied isotope dilution coupled with careful isotope ratio measurements on the ICP-MS offers precision and accuracy for blood Pb analyses beyond what is currently obtainable with routine methods.     

地球化学样品中钒检测方法的对比

地球化学样品中钒的测定方法主要有原子吸收光谱法、等离子体发射光谱法(ICP-AES)、电感耦合等离子体质谱法(ICP-MS)和X射线荧光光谱法.选用国家一级标样,分别用4种方法测定样品含量值,依次对方法检出限、准确度、精密度、加标回收率作比较.经对比,4种方法测定值与推荐值都基本吻合.等离子体发射光谱法检出限低,线性范围更宽,准确度与精密度更好,更适用于地球化学样品中钒批量的测试.     

Field-portable X-ray fluorescence spectrometry as rapid measurement tool for landfill mining operations: comparison of field data vs. laboratory analysis

Landfill mining applied in reclamation at the territories of old dump sites and landfills is a known approach tended to global economic and environmental benefits as recovery of metals and energy is an important challenge. The aim of this study was to analyse the concentration of several metallic elements (Ca, Cu, Cr, Fe, K, Mn, Pb, Zn) in the fine fraction of waste derived in the landfill and to compare the results of measurements obtained by field-portable equipment with the data gained by advanced analytical tools. Atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) were used for the quantitative detection of metallic elements at the laboratory; whereas field-portable X-ray fluorescence spectrometry (FPXRF) was applied for rapid sample characterisation in the field (on-site). Wet digestion of samples (fine fraction of waste at landfill) was done prior analytical procedures at the laboratory conditions, but FPXRF analysis was performed using raw solid samples of waste fine fraction derived in the Kudjape Landfill in Estonia. Although the use of AAS and ICP-MS for the measurements of metals achieves more precise results, it was concluded that precision and accuracy of the measurements obtained by FPXRF is acceptable for fast approximate evaluation of quantities of metallic elements in fine fraction samples excavated from the waste at landfills. Precision and accuracy of the results provided by express method is acceptable for quick analysis or screening of the concentration of major and trace metallic elements in field projects; however, data correction can be applied by calculating moisture and organic matter content dependent on sample matrix as well as special attention must be paid on sample selection and homogenisation and number of analysed samples.     

多接收器电感耦合等离子体质谱方法的开发和应用进展

稳定同位素分析是分析化学一项颇具前景的分支,通过精确测定物质的稳定同位素比值,可以追溯物质来源并探究其转化过程。高精度稳定同位素分析技术的进步依赖于新一代质谱仪的不断发展。其中,多接收器电感耦合等离子体质谱(MC-ICP-MS)是近年发展迅速的一种同位素组成测定工具。稳定同位素分析对样品基质十分敏感,复杂基质能严重干扰同位素测定的精密度和准确度。这对MC-ICP-MS的样品净化提出了极高要求,目前也是同位素分析领域的热点问题。该文聚焦于近年来MC-ICP-MS在样品净化及仪器联用方法方面的相关研究进展,并展望了MC-ICP-MS稳定同位素分析的应用前景。     

Heavy Metal Determination by Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) and Direct Mercury Analysis (DMA) and Arsenic Mapping by Femtosecond (fs) – Laser Ablation (LA) ICP-MS in Cereals

A study of the lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) contents in popular cereals was conducted using inductively coupled plasma – mass spectrometry (ICP-MS), direct mercury analysis (DMA), and femtosecond laser ablation – inductively coupled plasma – mass spectrometry (fs-LA-ICP-MS). For Pb, Cd, and As determination, the samples were prepared using microwave digestion, while for Hg, the samples were homogenized and measured by DMA without additional pretreatment. Satisfactory values for all of the quality parameters that include the SD, limit of detection (LOD), limit of quantitation (LOQ), accuracy, and recovery were obtained, clearly validating the analytical techniques used in the current study. Recovery and accuracy measurements were done using rice flour CRM 108-01-002 from Korea Research Institute of Standards and Science (KRISS). All measured concentrations for these elements were lower than the national regulatory guideline values provided by the CODEX Alimentarius and Ministry of Food and Drug Safety. A sample from each group was also selected for an As distribution study within a grain using fs-LA-ICP-MS. As is classified as a first-class carcinogen by the International Agency for Research on Cancer (IARC). For adlay, oats, and barley, As was determined to be primarily distributed in the area where the grain splits, while for foxtail millet, sorghum and corn, As was concentrated in the grain embryo. Also, it was confirmed that the exposure of heavy metals in the diet was negligible due to the low metal concentrations consumed daily in these foods.     

Comparison and evaluation of cloud point extraction and low-temperature directed crystallization as preconcentration tools for the determination of trace elements in environmental samples

A comparative study between cloud point extraction (CPE) and low-temperature directed crystallization (LTDC) is presented. Trace elements (Cd, Pb, Cr, Cu, Zn, Ni and Fe) were preconcentrated by both methods from model and natural water samples and the results were evaluated with respect to extraction efficiency, accuracy, precision, sample throughput and interferences. Flame atomic absorption spectrometry (FAAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) were used for the final measurements. The results indicate that these extraction and preconcentration procedures ensure the required accuracy and precision for the reliable identification and quantification of trace elements in natural waters. Drawbacks of each method identified can further assist the analyst towards a better application of each method depending on the target species, the detector employed and the application intended (routine analysis, trace analysis, speciation analysis, etc.).     

Comparison of ICP-AES and ICP-MS for the Analysis of Trace Elements in Soil Extracts

Abstract

The extraction of the chemical species Cr, Ni, Cu, Zn, Cd, and Pb, operationally defined, from a sewage sludge treated soil with various extractants (ammonium acetate, acetic acid and EDTA) has been studied by using two analytical techniques: inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). A comparison of the mean values measured by the two techniques with the t-criterion reveal that the differences are not significant in all the extractants mentioned above.

Results are also compared with data from a laboratory intercomparison exercise organized in the BCR-programme (Bureau Communautaire de Reference) and discussed. A fast screening of the concentration of other trace metals could be provided by ICP-MS with good precision and low detection limits.     

Determination of Manganese by Cathodic Stripping Voltammetry on a Microfabricated Platinum Thin–film Electrode

In this work, we report on the determination of trace manganese (Mn) using cathodic stripping voltammetry (CSV) using a microfabricated sensor with a Pt thin‐film working electrode. While an essential trace metal for human health, prolonged exposure to Mn tends to gradually impair our neurological system. The potential sources of Mn exposure make it necessary to monitor the concentration in various sample matrices. Previous work by us and others suggested CSV as an effective method for measuring trace Mn. The analytical performance metrics were characterized and optimized, leading to a calculated limit of detection (LOD) of 16.3 nM (0.9 ppb) in pH 5.5, 0.2 M acetate buffer. Further, we successfully validated Mn determination in surface water with ∼90% accuracy and >97% precision as compared with inductively coupled plasma mass spectrometry (ICP‐MS) “gold standard” measurement. Ultimately, with stable, accurate and precise electrochemical performance, this Pt sensor permits rapid monitoring of Mn in environmental samples, and could potentially be used for point‐of‐use measurements if coupled with portable instrumentation.     

Determination of stoichiometry and concentration of trace elements in thin BaxSr1-xTiO3 perovskite layers

This paper describes an analytical procedure for determining the stoichiometry of BaxSr1-xTiO3 perovskite layers using inductively coupled plasma mass spectrometry (ICP-MS). The analytical results of mass spectrometry measurements are compared to those of X-ray fluorescence analysis (XRF). The performance and the limits of solid-state mass spectrometry analytical methods for the surface analysis of thin BaxSr1-xTiO3 perovskite layers sputtered neutral mass spectrometry (SNMS)--are investigated and discussed.     

电感耦合等离子体质谱法(ICP-MS)测定废水中有害元素银的含量

为了寻求一种更加适合废水中低含量银的测定方法,本文采用石墨电热板消解-电感耦合等离子体质谱法测定废水中的低含量银离子。通过仪器工作条件最优化、测定线性回归方程、检出限、准确度、精密度、实际样品加标回收率,并与电感耦合等离子体发射光谱法（ICP-AES）的实际样品测定结果进行比对来评价该方法的实用性。石墨电热板消解-电感耦合等离子体质谱法前处理方法简便,分析速度快且该方法检出限较低,为0.03ug/L,标准样品测定的相对误差为-0.7%～1.7%,相对标准偏差为1.1%～2.5%,实际样品加标回收率在97.0%～103%之间,回收率高,能够满足废水中低含量银的测定。     

ICP-AES versus (LA-)IPC-MS: Competition or a happy marriage? – A view supported by current data

An assessment of the practical implementation of several spectroscopic analysis methods in the analytical service department of the reserach laboratory of a large electronic industry is provided. The emphasis is on inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The evolution of these methods in the department in recent years and their present position in the light of the analysis requests is introductory discussed. A “preview” assessment of the methods in terms of their strong and weak points then forms the basis for a subsequent discussion in which representative examples are used to illustrate in detail why in a particular situation a particular method is applied as the preferred one. It is concluded that ICP-AES is the most rugged and flexible, and therefore the most often applied method, while ICP-MS is uniquely suitable for ultra-trace and survey analysis of solutions and LA-ICP-MS is uniquely suitable for direct solids and local analysis. The ultimate conclusion is that neither of the three methods alone can answer all the analytical questions: they supplement and complement each other, and may even require supplementation by classical analytical methods.     

Trace analysis of high-purity graphite by LA–ICP–MS

Laser-ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) has been established as a very efficient and sensitive technique for the direct analysis of solids. In this work the capability of LA–ICP–MS was investigated for determination of trace elements in high-purity graphite. Synthetic laboratory standards with a graphite matrix were prepared for the purpose of quantifying the analytical results. Doped trace elements, concentration 0.5 μg g^–1, in a laboratory standard were determined with an accuracy of 1% to ± 7% and a relative standard deviation (RSD) of 2–13%. Solution-based calibration was also used for quantitative analysis of high-purity graphite. It was found that such calibration led to analytical results for trace-element determination in graphite with accuracy similar to that obtained by use of synthetic laboratory standards for quantification of analytical results. Results from quantitative determination of trace impurities in a real reactor-graphite sample, using both quantification approaches, were in good agreement. Detection limits for all elements of interest were determined in the low ng g^–1 concentration range. Improvement of detection limits by a factor of 10 was achieved for analyses of high-purity graphite with LA–ICP–MS under wet plasma conditions, because the lower background signal and increased element sensitivity. Received: 4 January 2001 / Revised: 27 March 2001 / Accepted: 28 March 2001     

土壤中铅的分析方法比对

对不同的样品消解方法及电感耦合等离子体质谱、电感耦合等离子体原子发射光谱、石墨炉原子吸收光谱法测定土壤中铅的测定结果进行比对。采用电热板、微波及水浴3种加热方式,选择硝酸、氢氟酸、双氧水、王水、高氯酸、盐酸的不同组合进行土壤样品消解,通过分析测定值的精密度和准确度,考察消解体系对电感耦合等离子体质谱、电感耦合等离子体发射光谱、石墨炉原子吸收光谱法测定结果的影响。结果表明采用电感耦合等离子体质谱法测定土壤中的铅,最适宜的消解体系是硝酸-氢氟酸-高氯酸(微波加热),采用电感耦合等离子体原子发射光谱法测定最适宜的消解体系是硝酸(电热板加热),采用石墨炉原子吸收光谱法测定最适宜的消解体系是硝酸-盐酸-高氯酸(微波加热)。电感耦合等离子体质谱法的精密度和准确度优于另外两种方法。     

Uncertainty evaluation in the analysis of biological samples by sector field inductively coupled plasma mass spectrometry. Part A: measurements of Be,Cd, Hg,Ir, Pb,Pd, Pt,Rh, Sb,U, Tl and W in human serum

A protocol that utilises data (trueness/recovery, precision and robustness) from validation tests to calculate measurement uncertainty was described and applied to a sector field inductively coupled plasma mass spectrometry (SF‐ICP‐MS)‐based method for the determination of Be, Cd, Hg, Ir, Pb, Pd, Pt, Rh, Sb, U, Tl and W in human serum. The method was validated according to criteria issued by international bodies such as AOAC, Eurachem and ISO and the uncertainty in the analytical measurements was estimated following the Eurachem/Citac guide. The methodology was based on dilution of human serum with water and analysis by serum‐matched standard calibration. The method quantification limits ranged 0.02 µg/L (Tl, Ir) to 0.26 µg/L (Hg). The coefficients of regression were greater than 0.9991 over a range of two orders of magnitude of concentration. The mean trueness was 101% and the mean recovery on three levels of fortification (1‐, 1.5‐, and 2‐times the baseline serum level) ranged between 93.3% and 106%. The maximum relative standard deviation values for repeatability and within‐laboratory reproducibility were 12.8% and 13.5%. The method was robust to slight variations of some critical factors relevant to the sample preparation and SF‐ICP‐MS instrumentation. The relative expanded uncertainty over three levels of concentration ranged from 11.6% (Hg) to 27.6% (Pt), and the uncertainty on the within‐laboratory reproducibility, which included factors such as time, analyst and calibration, represented the main contribution to the overall uncertainty. Copyright © 2010 John Wiley & Sons, Ltd.     

Precise and traceable carbon isotope ratio measurements by multicollector ICP-MS: what next?

This article reviews recent developments in the use of multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) to provide high-precision carbon isotope ratio measurements. MC-ICP-MS could become an alternative method to isotope ratio mass spectrometry (IRMS) for rapid carbon isotope ratio determinations in organic compounds and characterisation and certification of isotopic reference materials. In this overview, the advantages, drawbacks and potential of the method for future applications are critically discussed. Furthermore, suggestions for future improvements in terms of precision and sensitivity are made. No doubt, this is an exciting analytical challenge and, as such, hurdles will need to be cleared.