Isotope analysis of strontium by multicollector inductively-coupled plasma mass spectrometry: High-precision combined measurement of 88Sr/86Sr and 87Sr/86Sr isotope ratios

The paper describes a new high-precision method for the simultaneous precise determination of ⁸⁸Sr/⁸⁶Sr and ⁸⁷Sr/⁸⁶Sr ratios in a single portion of a geological sample by multicollector inductively coupled mass spectrometry (MC-ICP-MS). The isotope analysis is carried out with mass bias effect correction by a combination of internal normalization to the standard Zr-isotope ratio and bracketing standard method (external normalization). Our results for geochemical IAPSO and BCR-1 standard samples are in a good agreement with the published data. The reproducibility of the ⁸⁸Sr/⁸⁶Sr ratio varies from ±0.015 to ±0.05?? (depending on the sample features) and, together with the analysis accuracy, is superior to the previously reported methods of MC-ICP-MS analysis. Still ahead is only double spike thermal ionization mass spectrometry with its ±0.02?? reproducibility. However, the new method allows the simultaneous determination of ⁸⁸Sr/⁸⁶Sr and ⁸⁷Sr/⁸⁶Sr ratios and its productivity is higher by 5 to 6 times. On the other hand, in sample preparation, it is necessary to strive for at least 95% Sr yield from the chromatographic column; otherwise the sorption-desorption process may lead to a 0.6?? ⁸⁸Sr/⁸⁶Sr ratio bias relative to the true value.     

High-precision direct determination of the Sr/Sr isotope ratio of bottled Sr-rich natural mineral drinking water using multiple collector inductively coupled plasma mass spectrometry

We describe a precise and accurate method for the direct determination of the ⁸⁷Sr/⁸⁶Sr isotope ratio of bottled Sr-rich natural mineral drinking water using multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The method is validated by the comparative analysis of the same water with and without cation-exchange resin purification. The work indicates that isobarically interfering elements can be corrected for when ⁸⁷Rb/⁸⁶Sr < 0.05 (Rb/Sr < 0.015), and that the matrix elements (Ca, Mg, K and Na) have no significant effect on the accuracy of the Sr isotope data. The method is simple, rapid, eliminates sample preparation time, and avoids potential contamination during complicated sample-preparation procedures. Therefore, the high sample throughput inherent to the MC-ICP-MS can be fully exploited.     

Comparing the capability of collision/reaction cell quadrupole and sector field inductively coupled plasma mass spectrometers for interference removal from 90Sr, 137Cs,and 226Ra

Here we report a quantitative comparison of sector field inductively coupled plasma mass spectrometry (ICP-SFMS) and collision/reaction cell inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) for the detection of ⁹⁰Sr, ¹³⁷Cs, and ²²⁶Ra at ultra-trace levels. We observed that the identification and quantification of radioisotopes by ICP-MS were hampered by spectral (both isobaric and polyatomic ions) and non-spectral (matrix effect) interferences. ICP-QMS has been used to eliminate the isobaric ⁹⁰Sr/⁹⁰Zr interference through the addition of O₂ into the collision cell as a reactant gas. Zr⁺ ions were subsequently converted into ZrO⁺, whereas Sr⁺ ions were not reactive. In addition, the isobaric interference of ¹³⁷Ba on ¹³⁷Cs was eliminated by the addition of N₂O gas in the cell, which led to the formation of BaO⁺ and BaOH⁺ products, whereas Cs⁺ remained unreactive. Furthermore, He and H₂ were used in the collision/reaction cell to eliminate polyatomic ions formed at m/z 226. A comparison of the results obtained by ICP-SFMS after a chemical separation of Sr from Zr and Cs from Ba was performed. Finally, to validate the developed analytical procedures, measurements of the same samples were performed by γ-ray spectroscopy.     

Activation cross sections and isomeric cross section ratios for 184Os(n,2n)183m,gOs, 190Os(n,p)190m,gRe and 86Sr(n,2n)85m,gSr reactions from 13.5 to 14.8 MeV

The cross sections for the ¹⁸⁴Os(n,2n)^183m,gOs, ¹⁹⁰Os(n,p)^190m,gRe and ⁸⁶Sr(n,2n)^85m,gSr reactions and their isomeric cross section ratios σ _m /σ _g have been measured in the neutron energy range of 13.5–14.8 MeV using the activation technique. Nuclear model calculations using the code HFTT, which employs the Hauser-Feshbach (statistical model) and exciton model (precompound effects) formalisms, were undertaken to describe the formation of the products. The total cross sections for ¹⁸⁴Os(n,2n)¹⁸³Os, ¹⁹⁰Os(n,p)¹⁹⁰Re and ⁸⁶Sr(n,2n)⁸⁵Sr reactions are compared with the experimental data found in the literature, with results of published empirical formulae, with values of model calculations including the pre-equilibrium contribution, and with the evaluation data of JEFF-3.1/A or ENDF/B-VII.     

Comparison of analytical methods: ICP-QMS,ICP-SFMS and FF-ET-AAS for the determination of V,Mn, Ni,Cu, As,Sr, Mo,Cd and Pb in ground natural waters

Three analytical methods, namely, inductively coupled plasma sector field mass spectrometry (ICP-SFMS); inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) and filter-furnace electrothermal atomic-absorption spectroscopy (FF-ET-AAS) for the determination of V, Mn, Ni, Cu, As, Sr, Mo, Cd and Pb in ground natural water samples were compared and evaluated for their capacity to provide reliable and precise results. Two certified reference materials (SLEW-3 Estuarine Water; SLRS-4 River Water) were analysed to prove that accurate results could be obtained by using all the listed methods with properly optimised parameters. The limit of detection (LOD) for V, Mn, Ni, Cu, As, Sr, Mo, Cd and Pb provided by the ICP-MS methods ranged from 0.001 to 0.05 µg L^?1. Such LOD proved sufficient for the reliable determination of the listed elements in ground natural waters. However, the LOD of the FF-ET-AAS was approximately two orders of magnitude higher than that of ICP-MS, which made it impossible to quantify V, Mn, Ni, Mo and Pb. The effects of the usage of the collision cell mode in ICP-QMS and of the desolvation system Apex for ICP-SFMS to eliminate oxide ions levels were investigated. For all three analytical methods, the influence of the matrix effect on the results of the determination of the investigated elements using matrix model solution, external calibration and standard addition methods was evaluated. A comparison using a paired Student’s t-test between the results obtained by both ICP-MS methods for V, Mn, Ni, Cu, As, Sr, Mo, Cd and Pb concentrations in ground natural waters showed that there was no significant difference on a 95% confidence level. The precision of the results for ICP-SFMS, ICP-QMS and FF-ET-AAS varied between ~0.5 and 11; 2.5 and 12.5; 3 and 13.5%, respectively. Moreover, ICP-SFMS equipped with the desolvation system APEX proved a better choice for As, Cu and Mn analysis due to its better LOD (0.008, 0.03 and 0.02 µg L^?1, respectively) and precision (S_r ≤ 5.0; 7.5; 9.0%, respectively) compared to ICP-QMS and FF-ET-AAS.     

Improved sample preparation method for environmental plutonium analysis by ICP-SFMS and alpha-spectrometry

A rapid and simple sample preparation method for plutonium determination in environmental samples by inductively coupled plasma sector field mass spectrometry (ICP-SFMS) and alpha-spectrometry is described. The developed procedure involves a selective CaF₂ co-precipitation for preconcentration followed by extraction chromatographic separation. The proposed method effectively eliminates the possible interferences in mass spectrometric analysis and also removes interfering radionuclides that may disturb alpha-spectrometric measurement. For ²³⁹Pu, ²⁴⁰Pu and ²⁴¹Pu limits of detection of 9.0 fg·g⁻¹ (0.021 mBq), 1.7 fg·g⁻¹ (0.014 mBq) and 3.1 fg·g⁻¹ (11.9 mBq) were achieved by ICP-SFMS, respectively, and 0.02 mBq by alpha-spectrometry. Results of certified reference materials agreed well with the recommended values.     

Strontium isotope ratios (87Sr/86Sr) of tooth enamel: a comparison of solution and laser ablation multicollector inductively coupled plasma mass spectrometry methods

Strontium isotope ratios (87Sr/86Sr) in tooth enamel provide a means to investigate migration and landscape use in humans and other animals. Established methods for measuring (87)Sr/(86)Sr in teeth use bulk sampling (5-20 mg) and labor-intensive elemental purification procedures before analysis by either thermal ionization mass spectrometry (TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Another method for measuring 87Sr/86Sr is laser ablation MC-ICP-MS, but concerns have been expressed about its accuracy for measuring tooth enamel. In this study we test the precision and accuracy of the technique by analyzing 30 modern rodent teeth from the Sterkfontein Valley, South Africa by laser ablation MC-ICP-MS and solution MC-ICP-MS. The results show a mean difference in 87Sr/86Sr measured by laser ablation and by solution of 0.0003 +/- 0.0002. This degree of precision is well within the margin necessary for investigating the potential geographic origins of humans or animals in many areas of the world. Because laser ablation is faster, less expensive, and less destructive than bulk sampling solution methods, it opens the possibility for conducting 87Sr/86Sr analyses of intra-tooth samples and small and/or rare specimens such as micromammal and fossil teeth.     

Evaluation of strontium isotope abundance ratios in combination with multi-elemental analysis as a possible tool to study the geographical origin of ciders

In order to evaluate alternative analytical methodologies to study the geographical origin of ciders, both multi-elemental analysis and Sr isotope abundance ratios in combination with multivariate statistical analysis were estimated in 67 samples from England, Switzerland, France and two Spanish regions (Asturias and the Basque Country). A methodology for the precise and accurate determination of the ⁸⁷Sr/⁸⁶Sr isotope abundance ratio in ciders by multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) was developed. Major elements (Na, K, Ca and Mg) were measured by ICP-AES and minor and trace elements (Li, Be, B, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Mo, Cd, Sn, Sb, Cs, Ba, La, Ce, W, Tl, Pb, Bi, Th and U) were measured by ICP-MS using a collision cell instrument operated in multitune mode. An analysis of variance (ANOVA test) indicated that group means for B, Cr, Fe, Ni, Cu, Se, Cd, Cs, Ce, W, Pb, Bi and U did not show any significant differences at the 95% confidence level, so these elements were rejected for further statistical analysis. Another group of elements (Li, Be, Sc, Co, Ga, Y, Sn, Sb, La, Tl, Th) was removed from the data set because concentrations were close to the limits of detection for many samples. Therefore, the remaining elements (Na, Mg, Al, K, Ca, Ti, V, Mn, Zn, As, Rb, Sr, Mo, Ba) together with ⁸⁷Sr/⁸⁶Sr isotope abundance ratio were considered for principal component analysis (PCA) and linear discriminant analysis (LDA). Finally, LDA was able to classify correctly 100% of cider samples coming from different Spanish regions, France, England and Switzerland when considering Na, Mg, Al, K, Ca, Ti, V, Mn, Zn, As, Rb, Sr, Mo, Ba and ⁸⁷Sr/⁸⁶Sr isotope abundance ratio as original variables.     

Arsenic‐Containing Phosphatidylcholines: A New Group of Arsenolipids Discovered in Herring Caviar

A new group of arsenolipids based on cell‐membrane phosphatidylcholines has been discovered in herring caviar (fish roe). A combination of HPLC with elemental and molecular mass spectrometry was used to identify five arsenic‐containing phosphatidylcholines; the same technique applied to salmon caviar identified an arsenic‐containing phosphatidylethanolamine. The arsenic group in these membrane lipids might impart particular properties to the molecules not displayed by their non‐arsenic analogues. Additionally, the new compounds have human health implications according to recent results showing high cytotoxicity for some arsenolipids.     

The determination and application of 87Sr/86Sr ratio in verifying geographical origin of wheat

As ⁸⁷Sr/⁸⁶Sr ratio plays a significant role in authenticating the geographical origin of foodstuff, it is important to identify where the ⁸⁷Sr/⁸⁶Sr signature in food comes from, and the methods of ⁸⁷Sr/⁸⁶Sr ratio analysis in food and environmental samples. Wheat with three genotypes, soil and groundwater samples were collected from three regions of China during harvest time of 2014. The ⁸⁷Sr/⁸⁶Sr ratios in the samples were determined by thermal ionization mass spectrometer in order to investigate the possible source of ⁸⁷Sr/⁸⁶Sr in wheat, and the concentrations of Rb and Sr in wheat and soils were also detected by inductively coupled plasma mass spectrometry and combined with ⁸⁷Sr/⁸⁶Sr ratio in order to trace the geographical origin of wheat. The ⁸⁷Sr/⁸⁶Sr ratio, the contents Rb and Sr, and Rb/Sr ratio of wheat and soil samples showed significant differences among three regions. The ⁸⁷Sr/⁸⁶Sr ratios and the concentrations of Rb and Sr in soils were higher than those in corresponding wheat. The ⁸⁷Sr/⁸⁶Sr ratio in wheat was identical to that corresponding soil NH₄NO₃ extracts (labile fraction of soil) and groundwater. Wheat uptake more Rb than Sr. 3D distribution of ⁸⁷Sr/⁸⁶Sr, Rb and Sr could identify wheat samples from different regions clearly. The ⁸⁷Sr/⁸⁶Sr ratio of wheat reflects the ⁸⁷Sr/⁸⁶Sr ratio of the associated environment including soil and groundwater. It is expected that the use the parameters of ⁸⁷Sr/⁸⁶Sr ratio, the contents of Rb and Sr will allow to trace geographical origin of wheat. Copyright © 2017 John Wiley & Sons, Ltd.     

Determination of rare-earth elements in uranium-bearing materials by inductively coupled plasma mass spectrometry

A novel and simple analytical procedure has been developed for the trace-level determination of lanthanides (rare-earth elements) in uranium-bearing materials by inductively coupled plasma sector-field mass spectrometry (ICP-SFMS). The method involves a selective extraction chromatographic separation of lanthanides using TRU™ resin followed by ICP-SFMS analysis. The limits of detection of the method proposed is in the low pg g⁻¹ range, which are approximately two orders of magnitude better than that of without chemical separation. The method was validated by the measurement of reference material and applied for the analysis of uranium ore concentrates (yellow cakes) for nuclear forensic purposes, as a potential application of the methodology.     

A new method for calibrating the current gain of 1013 Ω amplifiers in thermal ionization mass spectrometry

We report a new method for calibrating the current gain of 10¹³ Ω amplifiers in both positive and negative mode used in thermal ionisation mass spectrometry (TIMS). This method uses any isotopic standard or sample to calibrate the gain factor as long as it can produce a stable current signal. It is simpler and more flexible than that recommended by Thermo‐Fisher (the manufacture of the TIMS). In these analyses, the gains of five 10¹³ Ω amplifiers were assessed. The precision of gain factors was better than 100 ppm (2 RSD) in a day, and the long‐term reproducibility was better than 300 ppm (2 RSD) within 2 to 8 months. After a gain was calibrated, the ratio accuracy and precision in the positive mode for ⁸⁷Sr/⁸⁸Sr of NIST 987 Sr and ¹⁴³Nd/¹⁴⁴Nd of La Jolla Nd were 0.710242 ± 60 (2 SD, n = 14) and 0.511842 ± 10 (2 SD, n = 22), respectively, at intensities of ⁸⁸Sr 0.3 V and ¹⁴²Nd 0.4 V, while in the negative mode for ¹⁸⁷Os/¹⁸⁸Os of Merck Os was 0.120229 ± 34 (2 SD, n = 23) at an intensity of ¹⁸⁷OsO₃ 0.01 mV. In addition, a difference in the gain factors between the negative mode TIMS (NTIMS) and positive mode TIMS (PTIMS) has been recognized. The values of the gain factor for NTIMS and PTIMS show a deviation of 0.54% on the Triton and 0.31% on the Triton Plus TIMS in this study; therefore, gain calibration should be carried out on both NTIMS and PTIMS. Moreover, a bias of ~ 1.5 × 10⁻⁵ between H and L Faraday cups for the same 10¹³ Ω amplifier has been detected, hinting that the efficiency of different Faraday cups may affect the gain factors, which can be eliminated through the new method of “cross‐calibration” discribed in this study.     

Direct determination of cadmium in natural waters by electrothermal atomic absorption spectrometry without matrix modification

A procedure for the determination of cadmium in fresh, coastal and estuarine waters by polarized Zeeman-effect graphite-furnace atomic absorption spectrometry is validated by using lake waters and seawater. The limit of detection for freshwaters is <2 ng l^?1 cadmium. Undiluted seawater can be analyzed directly without the addition of matrix modifiers with the aid of a stabilized temperature platform. The instrument is calibrated with diluted NBS SRM 1643a (Trace Elements in Water). Analytical performance was tested extensively with fresh and brackish water samples and procedures were worked out to ensure that a high degree of accurately is achieved consistently.     

Rapid determination of 89,90Sr in wide range of activity concentration by combination of yttrium, strontium separation and Cherenkov counting

The methodology for the rapid determination of ^89,90Sr in wide range of activity concentration is given. Methodology is based on simultaneous separation of strontium and yttrium from samples by mixed solvent anion exchange chromatography, mutual separation of ^89,90Sr from ⁹⁰Y by hydroxide precipitation and quantitative ^89,90Sr determination by Cherenkov counting within 3 days. It is shown that Y and Sr can be efficiently separated from alkaline, alkaline earth and transition elements as well as from lanthanides and actinides on the column filed by strong base anion exchanger in nitrate form and 0.25 M HNO₃ in mixture of ethanol and methanol as eluent. Decontamination factor for Ba, La and other examined elements except calcium is low and can not affect quantitative determination in predictable circumstances. Methodology for quantitative determination by Cherenkov counting based on following the changes of sample activity over time is described and discussed. It has been shown that ^89,90Sr can be determined with acceptable accuracy when ⁸⁹Sr/⁹⁰Sr ratio is over 10:1 and that separation of Y enables reliable determination of ⁸⁹Sr and ⁹⁰Sr in wide range of ⁸⁹Sr/⁹⁰Sr ratios (60:1) and in some cases in presence of other yttrium and strontium isotopes. The methodology was tested by determination of ^89,90Sr in Analytics crosscheck samples (nuclear waste sample) and ERA proficiency testing samples (low level activity samples). Obtained results shows that by using of low level liquid scintillation counter it can be possible to determine ⁸⁹Sr and ⁹⁰Sr in wide range of concentration activity (1–1,000 Bq/L/kg) with uncertainty below 10% within 2–3 days. Results also show that accuracy of determination of ⁸⁹Sr (and ⁹⁰Sr) strongly depends on the determination of difference between separation and counting time when activity ratio of ⁸⁹Sr/⁹⁰Sr is high. Examination the influence of media and vial type on background radiation and counting efficiency has shown that lowest limit of determination can be obtained by using of HNO₃ in plastic vials as counting media, because in this combination figure of merit is maximized. For the recovery of 50% and 100 min of counting time estimated MDA is 55 Bq and 90 Bq for ⁹⁰Sr and ⁸⁹Sr, respectively. Analysis of combined uncertainty shows that it mainly depends on uncertainty of efficiency and recovery determination, uncertainty of activities determination for both isotopes and level of background radiation.     

Development of field portable sampling and analysis systems

A portable, field rugged, sampling and analysis system has been developed for the rapid screening of aqueous samples during scoping and remediation studies. Using field portable equipment, water is pumped through ion selective solid phase extraction (SPE) disks, at a flow rate of 150-250 ml/min, and counted for the radionuclide of interest in the field using portable detectors. SPE disks are currently available to selectively concentrate ⁹⁹Tc, ⁹⁰Sr, radiocesium (¹³⁴Cs and ¹³⁷Cs) and radium isotopes. In the field the radiocesium concentration is determined by gamma-spectrometry, ⁹⁰Sr and ⁹⁹Tc are determined by beta-counting. A one-liter sample can be processed and ready for counting within ten minutes. Using a 5-minute counting time, a detection limit of <50 pCi/l for ⁹⁹Tc or ⁹⁰Sr and ~50 pCi/l for ¹³⁷Cs has been achieved. Up to 10 liters of water have been processed for the analysis of ⁹⁹Tc and ¹³⁷Cs when lower limits of detection were required. The sampling and analysis system has been field tested at the Savannah River Site (SRS), Aiken SC, and the Hanford Site, Richland WA. The SRS H-area tank farm storm water runoff system was analyzed for ⁹⁰Sr and ¹³⁷Cs. Groundwater from the SX tank farm at the Hanford Site was analyzed for ¹³⁷Cs and ⁹⁹Tc. Groundwater from seeps below the 100-H area at Hanford was analyzed for ⁹⁰Sr and ⁹⁹Tc.     

Calculation methods for direct internal mass fractionation correction of spiked isotopic ratios from multi-collector mass spectrometric measurements

It is difficult to do internal mass fractionation corrections for isotope dilution analysis by thermal ionization mass spectrometry (TIMS) or multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), especially for MC-ICP-MS. In this study, calculation methods for direct internal fractionation correction of spiked isotope analysis by TIMS or MC-ICP-MS cycle by cycle for elements having at least two internal reference isotopic ratios are presented. For TIMS, direct internal mass fractionation correction calculation methods, based on both power and exponential laws, are derived; whereas for MC-ICP-MS, due to larger mass fractionation effects, only exponential law is considered. These calculation strategies can be applied for both static and multi-dynamic measurements. For multi-dynamic measurements, the isotope fractionation effect, gain and cup efficiency effects of different collectors, as well as ion beam fluctuation effects are all simultaneously eliminated. The calculation methods were verified by Sr isotopic analyses of spiked NBS987 standard solutions by TIMS and Hf isotopic analyses of spiked geological reference materials by MC-ICP-MS. In addition, precise and accurate calibrations of isotopic ratios of the spikes, based on the calculation methods, are discussed.     

On variations of volumetric activity of 90Sr and 137Cs in the Baltic Sea coastal waters near the shore of Lithuania in 2005–2009

The article presents the measurement results of the volumetric activity (VA) of artificial radionuclides ⁹⁰Sr and ¹³⁷Cs in the coastal waters of the Baltic Sea near the Curonian Peninsula in 2005–2009. The annual average values for this period of time were 12 Bq/m³ (⁹⁰Sr) and 40 Bq/m³ (¹³⁷Cs). Considerable variations in the VA of the radionuclide in individual measurements compared to the average results were observed. The extreme values were 6 and 16 Bq/m³ for ⁹⁰Sr and for ¹³⁷Cs—27 and 75 Bq/m³. It is proposed to allow such variations under the influence of a variety of external factors such as hydro meteorological situations, inflowing rivers and bays, storm activity and etc. Besides, a possibility of penetration of radionuclides into the sea waters from the additional radioactive sources is not excluded.     

Intra‐ and inter‐tooth variation in strontium isotope ratios from prehistoric seals by laser ablation multi‐collector inductively coupled plasma mass spectrometry

Rationale

Strontium isotope ratios (⁸⁷Sr/⁸⁶Sr) in modern‐day marine environments are considered to be homogeneous (~0.7092). However, in the Baltic Sea, the Sr ratios are controlled by mixing seawater and continental drainage from major rivers discharging into the Baltic. This pilot study explores if variations in Sr can be detected in marine mammals from archaeological sites in the Baltic Sea.

Methods

⁸⁷Sr/⁸⁶Sr ratios were measured in tooth enamel from three seal species by laser ablation multi‐collector inductively coupled plasma mass spectrometry (LA‐MC‐ICP‐MS). The method enables micro‐sampling of solid materials. This is the first time that the method has been applied to marine samples from archaeological collections.

Results

The analyses showed inter‐tooth ⁸⁷Sr/⁸⁶Sr variation suggesting that different ratios can be detected in different regions of the Baltic Sea. Furthermore, the intra‐tooth variation suggests possible different geographic origin or seasonal movement of seals within different regions in the Baltic Sea through their lifetime.

Conclusions

The method was successfully applied to archaeological marine samples showing that: (1) the ⁸⁷Sr/⁸⁶Sr ratio in marine environments is not uniform, (2) ⁸⁷Sr/⁸⁶Sr differences might reflect differences in ecology and life history of different seal species, and (3) archaeological mobility studies based on ⁸⁷Sr/⁸⁶Sr ratios in humans should therefore be evaluated together with diet reconstruction.

     

Multi-elemental characterization of soft biological tissues by inductively coupled plasma-sector field mass spectrometry

The performance of double-focusing, sector field ICP-MS (ICP-SFMS) for the multi-elemental analysis of soft tissues following microwave-assisted digestion with nitric acid was evaluated and factors affecting method limits of detection discussed. Accuracy was assessed by replicate analyses of certified reference materials and by participation in performance evaluation programs; the precision was better than 5% relative standard deviation (RSD) for the majority of elements. Cl was the only element for which ICP-SFMS data consistently deviated from certified concentrations in the reference materials tested. Comparison between results obtained by ICP-SFMS and ICP optical emission spectrometry showed good agreement for elements present in tissues at concentrations above 2 μg g⁻¹. The concentrations of 68 elements in different fish and animal soft tissues (muscle, liver, kidney, lung and brain) are presented, and, where possible, compared with previously published data.     

Rapid determination of 237Np in soil samples by multi-collector inductively-coupled plasma mass spectrometry and gamma spectrometry

A radiochemical procedure is developed for the determination of ²³⁷Np in soil with multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) and gamma-spectrometry. ²³⁹Np (milked from ²⁴³Am) was used as an isotopic tracer for chemical yield determination. The neptunium in the soil is separated by thenoyl-trifluoracetone extraction from 1 M HNO₃ solution after reducing Np to Np(IV) with ferrous sulfamate, and then purified with Dowex 1 × 2 anion exchange resin. ²³⁹Np in the resulting solution is measured with gamma-spectrometry for chemical yield determination while the ²³⁷Np is measured with MC-ICP-MS. Measurement results for soil samples are presented together with those for two reference samples. By comparing the determined value with the reference value of the ²³⁷Np activity concentration, the feasibility of the procedure was validated.