Determination of Calcium Isotopes Using Inductive Coupled Plasma-Tandem Mass Spectrometry with Ozone-Induced Oxidation.

In this study, we propose a new method for determination of calcium (Ca) isotopes using inductive coupled plasma-tandem mass spectrometry (ICP-MS/MS). The most abundant isotope of Ca, 40Ca, has a spectrum identical with that of argon (Ar), which is often used as the carrier gas in ICP-MS analysis. The detection capability for 40Ca is thus significantly reduced in the presence of 40Ar. To avoid interference from 40Ar during the 40Ca measurements, ozone (O3) was used as the reaction gas in the ICP-MS/MS analysis. The reaction of Ca+ with O3 in the collision cell preferentially produced CaO3+. In contrast, the reaction between Ar+ and O3 produced ArO+, which further reacted with the oxidized O3 to produce Ar+. Because Ar+ does not produced ArO3+ as the main product of the reaction with O3, the measurement of Ca+ as CaO3 via O3-induced oxidation resulted in considerably less interference from Ar+. The detailed mechanism of CaO3+ formation was investigated via quantum chemistry calculations by using density functional theory. The interaction between Ca+ and O3 yielded CaO3+, which immediately dissociated into either Ca+ and O3 or CaO+ and O2 because the pressure in the collision cell was approximately 1 Pa in the MS/MS experiments. Consequently, CaO3+ was formed by the consecutive reaction of Ca+ with O3, with CaO+ and CaO2+ as intermediates. The present method achieved the detection of less abundant Ca isotopes in certified reference materials such as 43Ca, 44Ca, 46Ca, and 48Ca, thereby allowing the determination of Ca isotopes with high sensitivity.

Quantification of elemental area densities in multiple metal layers (Au/Ni/Cu) on a Cr-coated quartz glass substrate for certification of NMIJ CRM 5208-a.

Area densities of Au/Ni/Cu layers on a Cr-coated quartz substrate were characterized to certify a multiple-metal-layer certified reference material (NMIJ CRM5208-a) that is intended for use in the analysis of the layer area density and the thickness by an X-ray fluorescence spectrometer. The area densities of Au/Ni/Cu layers were calculated from layer mass amounts and area. The layer mass amounts were determined by using wet chemical analyses, namely inductively coupled plasma mass spectrometry (ICP-MS), isotope-dilution (ID-) ICP-MS, and inductively coupled plasma optical emission spectrometry (ICP-OES) after dissolving the layers with diluted mixture of HCl and HNO3 (1:1, v/v). Analytical results of the layer mass amounts obtained by the methods agreed well with each another within their uncertainty ranges. The area of the layer was determined by using a high-resolution optical scanner calibrated by Japan Calibration Service System (JCSS) standard scales. The property values of area density were 1.84 ± 0.05 µg/mm2 for Au, 8.69 ± 0.17 µg/mm2 for Ni, and 8.80 ± 0.14 µg/mm2 for Cu (mean ± expanded uncertainty, coverage factor k = 2). In order to assess the reliability of these values, the density of each metal layer calculated from the property values of the area density and layer thickness measured by using a scanning electron microscope were compared with available literature values and good agreement between the observed values and values obtained in previous studies.

Effect of ashing temperature on accurate determination of plutonium in soil samples.

An acidic leaching method using HNO3 is widely employed to release the global fallout Pu from soil samples for further chemical separations in radioecology and toxicology studies and in many applications using Pu as a useful tracer. In the method's sample ash treatment step to decompose organic matter in soil, various ashing temperatures (400-900 °C) are used; however, the effect of ashing temperature on the accurate Pu analysis has not been well investigated. In this study, two standard reference soils (IAEA-soil-6 and IAEA-375) were used to determine the ashing temperature effect (from 375 to 600 °C) on the HNO3 leaching method. The Pu analytical results of both standard reference materials showed that lower (239+240)Pu activity was observed when the ashing temperature exceeded 450 °C, and the (239+240)Pu activity continued to decrease as the ashing temperature was raised. Approximately 40% of the Pu content could not be leached out by concentrated HNO3 after ashing for 4 h at 600 °C. The Pu loss was attributed to the formation of refractory materials, which are insoluble in HNO3 solution. This hypothesis was confirmed by the XRD analysis of soil samples, which revealed that plagioclase-like silicate materials were formed after high-temperature ashing. To ensure Pu release efficiency in HNO3 leaching, we recommend 450 °C as the ideal ashing temperature. This recommendation is also useful for analysis of other important artificial radionuclides (e.g., (137)Cs, (90)Sr, (241)Am) for which an ashing process is needed to decompose the organic content in soil samples.

A layered P2- and O3-type composite as a high-energy cathode for rechargeable sodium-ion batteries.

A layered composite with P2 and O3 integration is proposed toward a sodium-ion battery with high energy density and long cycle life. The integration of P2 and O3 structures in this layered oxide is clearly characterized by XRD refinement, SAED and HAADF and ABF-STEM at atomic resolution. The biphase synergy in this layered P2+O3 composite is well established during the electrochemical reaction. This layered composite can deliver a high reversible capacity with the largest energy density of 640 mAh g(-1), and it also presents good capacity retention over 150 times of sodium extraction and insertion.

An ultrastable anode for long-life room-temperature sodium-ion batteries.

Sodium-ion batteries are important alternative energy storage devices that have recently come again into focus for the development of large-scale energy storage devices because sodium is an abundant and low-cost material. However, the development of electrode materials with long-term stability has remained a great challenge. A novel negative-electrode material, a P2-type layered oxide with the chemical composition Na(2/3)Co(1/3)Ti(2/3)O2, exhibits outstanding cycle stability (ca. 84.84 % capacity retention for 3000 cycles, very small decrease in the volume (0.046 %) after 500 cycles), good rate capability (ca. 41 % capacity retention at a discharge/charge rate of 10 C), and a usable reversible capacity of about 90 mAh g(-1) with a safe average storage voltage of approximately 0.7 V in the sodium half-cell. This P2-type layered oxide is a promising anode material for sodium-ion batteries with a long cycle life and should greatly promote the development of room-temperature sodium-ion batteries.

On-line generated ozone as a reactive cell gas for tandem quadrupole inductively coupled plasma mass spectrometry.

On-line generated ozone was introduced as the cell gas of tandem quadrupole inductively coupled plasma mass spectrometry. Product ions of the ozone reaction showed that the formation of singly charged monoxide ions and dioxide ions was apparently improved for most elements, resulting in maximum improvement of the signal intensity by over 1000 times.

Contamination, speciation, and health risk assessment of arsenic in leafy vegetables in Ambagarh Chowki (India).

Green leafy vegetables are essential for a balanced diet, providing vital nutrients for overall well-being. However, concerns arise due to contamination with toxic substances, such as arsenic, posing risks to food safety and human health. This study analyzes inorganic (iAs), monomethyl (MMA), and dimethyl arsenic (DMA) in specific leafy vegetables (Amaranthus tricolor L., Corchorus olitorius L., Cordia myxa L., Hibiscus sabdariffa L., Ipomoea batatas (L.) Lam., Moringa oleifera Lam., and Spinacia oleracea L.) grown in the heavily polluted Ambagarh Chouki region, Chhattisgarh, India. Concentrations of DMA, MMA, and iAs ranged from 0 to 155, 0 to 7, and 131 to 3579 mg·kg-1, respectively. The health quotient (HQ) for iAs ranged between 0.37 and 3.78, with an average value of 2.58 ± 1.08.

Detection of mosaicism for the polymorphic variants in the 5'-UTR of hOGG1 by cloning and sequence analysis and pyrosequencing.

Mosaicism refers to the presence of genetically distinct cell lines within an organism or a tissue. Somatic mosaicism exists in distinct populations of somatic cells and commonly arises as a result of somatic mutations, mainly in early embryonic development. SNPs are important markers that distinguish between different individuals in heterogeneous biological samples and contribute greatly to disease risk association studies. In this work, we investigated the relationship between the functional variants in the 5'-UTR of the hOGG1 gene and the risk of type 2 diabetes. Upon detection of the polymorphisms c.-53G>C, c.-23A>G, and c.-18G>T in the hOGG1 gene, we found that mosaicism was present in 3/28 (10.71%), 7/51 (13.73%), and 1/44 (2.27%) patients respectively, who were carriers of these single nucleotide variations, by cloning and sequence analysis and pyrosequencing. Statistical analysis showed that the frequency of the variation c.-23A>G in the hOGG1 5'-UTR in type 2 diabetic patients was significantly higher than that in healthy controls. However, sequencing of the mutant alleles in mosaic individuals showed weak peaks that may affect detection of the SNPs and impair association-based investigations.

Identification of possible technical problems in determination of the major inorganic constituents of brown-rice flour by evaluating proficiency test results.

To support skill upgrading in analysis of inorganic constituents of environmental and food samples, the National Metrology Institute of Japan (NMIJ) and the National Food Research Institute (NFRI) have organized a proficiency test (PT) of determination of Mn, Fe, Cu, Zn, As, and Cd in brown-rice flour based on the international standard (ISO/IEC 17043:2010). One hundred and thirty-three sets of reports were assessed by use of the E(n)-number and z-score approaches in accordance with ISO/IEC 17043 and the international harmonized protocol for PT. The PT results and analytical procedures, reported in detail, were reviewed, and possible technical reasons for questionable or unsatisfactory results are discussed.

[Establishment of a hMSH2/hMSH6 protein interaction system and functional evaluation of hMSH2 gene missense mutations].

OBJECTIVE: To construct a hMSH2/hMSH6 protein interaction system, and to use it for evaluating missense mutations detected in hMSH2 gene. METHODS: Recombinant plasmids pGADT7-hMSH2, pGBKT7-hMSH6 and 7 recombinant pGBKT7 plasmids with different hMSH6 domains were constructed through genetic engineering. Subsequently, site-directed mutagenesis was used to construct 10 mutant pGADT7-hMSH2 plasmids, which were transformed into yeast AH109. The growth of transformants was observed on a histidine-deficient culture. RESULTS: Both hMSH6 MutSII-V and MutSIII-V could interact with hMSH2 in yeast AH109. Yeast two-hybrid transformants pGADT7-hMSH2/pGBKT7-hMSH6 MutSII-V were used to construct a hMSH2/hMSH6 protein interaction system. Compared with wild-type hMSH2, yeast two-hybrid transformants c.505A>G, c.1168C>T, c.1255C>A, c.1261C>A could grow normally, c.1223A>G, c.1886A>G, c.2108C>A and c.2516A>G grew slowly, c.518T>G and c.1664 delA could not grow in a histidine-deficient medium in yeast AH109. CONCLUSION: A hMSH2/hMSH6 protein interaction system has been constructed with yeast two-hybrid system, which has been used for functional evaluation of hMSH2 gene missense mutations. c.518T>G is a pathological mutation. c.1223A>G, c.1886A>G, c.2108C>A, c.2516A>G may in part affect the hMSH2 function. And c.505A>G, c.1168C>T, c.1255C>A, c.1261C>A were innocuous variants.

A review on arsenic in the environment: contamination, mobility, sources, and exposure.

Arsenic is one of the regulated hazard materials in the environment and a persistent pollutant creating environmental, agricultural and health issues and posing a serious risk to humans. In the present review, sources and mobility of As in various compartments of the environment (air, water, soil and sediment) around the World are comprehensively investigated, along with measures of health hazards. Multiple atomic spectrometric approaches have been applied for total and speciation analysis of As chemical species. The LoD values are basically under 1 µg L-1, which is sufficient for the analysis of As or its chemical species in environmental samples. Both natural and anthropogenic sources contributed to As in air, while fine particulate matter tends to have higher concentrations of arsenic and results in high concentrations of As up to a maximum of 1660 ng m-3 in urban areas. Sources for As in natural waters (as dissolved or in particulate form) can be attributed to natural deposits, agricultural and industrial effluents, for which the maximum concentration of 2000 µg L-1 was found in groundwater. Sources for As in soil can be the initial contents, fossil fuel burning products, industrial effluents, pesticides, and so on, with a maximum reported concentration up to 4600 mg kg-1. Sources for As in sediments can be attributed to their reservoirs, with a maximum reported concentration up to 2500 mg kg-1. It is notable that some reported concentrations of As in the environment are several times higher than permissible limits. However, many aspects of arsenic environmental chemistry including contamination of the environment, quantification, mobility, removal and health hazards are still unclear.

A review on arsenic in the environment: bio-accumulation, remediation, and disposal.

Arsenic is a widespread serious environmental pollutant as a food chain contaminant and non-threshold carcinogen. Arsenic transfer through the crops-soil-water system and animals is one of the most important pathways of human exposure and a measure of phytoremediation. Exposure occurs primarily from the consumption of contaminated water and foods. Various chemical technologies are utilized for As removal from contaminated water and soil, but they are very costly and difficult for large-scale cleaning of water and soil. In contrast, phytoremediation utilizes green plants to remove As from a contaminated environment. A large number of terrestrial and aquatic weed flora have been identified so far for their hyper metal removal capacity. In the panorama presented herein, the latest state of the art on methods of bioaccumulation, transfer mechanism of As through plants and animals, and remediation that encompass the use of physicochemical and biological processes, i.e., microbes, mosses, lichens, ferns, algae, and macrophytes have been assessed. Since these bioremediation approaches for the clean-up of this contaminant are still at the initial experimental stages, some have not been recognized at full scale. Nonetheless, extensive research on these primitive plants as bio-accumulators can be instrumental in controlling arsenic exposure and rehabilitation and may result in major progress to solve the problem on a worldwide scale.

Preparation and certification of hijiki reference material, NMIJ CRM 7405-a, from the edible marine algae hijiki (Hizikia fusiforme).

A certified reference material, NMIJ CRM 7405-a, for the determination of trace elements and As(V) in algae was developed from the edible marine hijiki (Hizikia fusiforme) and certified by the National Metrology Institute of Japan (NMIJ), the National Institute of Advanced Industrial Science and Technology (AIST). Hijiki was collected from the Pacific coast in the Kanto area of Japan, and was washed, dried, powdered, and homogenized. The hijiki powder was placed in 400 bottles (ca. 20 g each). The concentrations of 18 trace elements and As(V) were determined by two to four independent analytical techniques, including (ID)ICP-(HR)MS, ICP-OES, GFAAS, and HPLC-ICP-MS using calibration solutions prepared from the elemental standard solution of Japan calibration service system (JCSS) and the NMIJ CRM As(V) solution, and whose concentrations are certified and SI traceable. The uncertainties of all the measurements and preparation procedures were evaluated. The values of 18 trace elements and As(V) in the CRM were certified with uncertainty (k = 2).

Determination of Rare Earth Elements by Inductively Coupled Plasma-Tandem Quadrupole Mass Spectrometry With Nitrous Oxide as the Reaction Gas.

Nitrous oxide (N2O) was investigated as the reaction gas for the determination of rare earth elements (REEs) by inductively coupled plasma-tandem quadrupole mass spectrometry (ICP-QMS/QMS). The use of N2O as the reaction gas apparently improved the yields of m M16O+ for Eu and Yb in the reaction cell. As a result, the sensitivities for measurement of Eu and Yb were apparently improved in comparison to those obtained with O2 as the reaction gas. A high sensitivity measurement of the whole set of REEs was achieved, providing a typical sensitivity of 300,000 CPS mL/ng for REEs measured with an isotope having isotopic abundance close to 100%. The use of N2O as the reaction gas helped suppress Ba-related spectral interferences with the measurement of Eu, permitting the measurement of Eu in a natural sample without mathematic correction of spectral interferences. The detection limits (unit, pg/mL) for 14 REEs (except for Pm) from La to Lu were 0.028, 0.018, 0.006, 0.026, 0.006, 0.010, 0.017, 0.006, 0.016, 0.010, 0.016, 0.004, 0.023, and 0.012, respectively. The validity of the present method was confirmed by determining REEs in river water-certified reference materials, namely, SLRS-3 and SLRS-4.

Pseudo isotope dilution (PID) as an approach for correcting barium-related spectral interferences on the measurement of europium by inductively coupled plasma mass spectrometry (ICP-MS).

Pseudo isotope dilution (PID) was suggested as a simple and practical approach for the correction of barium-related spectral interferences on the measurement of europium by inductively coupled plasma mass spectrometry (ICP-MS). The interferents, i.e. oxides and hydroxides of barium, were regarded as pseudo europium isotopes. An equation for calculating the concentration of europium was deduced and the net contribution of europium isotopes can be obtained by measuring the signal intensity ratios of 151I/153I in a sample, a europium standard, and a barium standard, respectively. The validity of the approach was confirmed by the determination of europium in standard solutions with different concentrations of barium. Determination of europium in river water and seawater certified reference materials was carried out, whose results were in coincidence with reference values.

Potential Anthropogenic Pollution of High-technology Metals with a Focus on Rare Earth Elements in Environmental Water.

In recent years, the utilization of high-technology metals such as rare earth elements (REEs), which exist in extremely low quantities in the Earth, has rapidly increased with the development of new types of industrial materials and pharmaceutical products. This review provides an overview of a new type of potential anthropogenic pollution caused by high-technology metals, with a focus on REEs released into environmental waters from waste treatment plants. In this paper, potential anthropogenic pollution was defined as pollution caused by metals gradually enriched in the environment by human activity, although standard and guideline concentrations of these elements are not regulated by environmental quality standards for water pollution. We review the analytical methods of REEs and the potential anthropogenic pollution of REEs with a focus on Gd, from the viewpoints of a comparison of the degree of Gd anomaly, chemical speciation, ecotoxicology, and bioaccessibility. Moreover, we also highlight the comprehensive analysis based on multielement analysis of high-technology metals as well as REEs for the further screening for potential anthropogenic pollution.

Determination of rare earth elements in seawater samples by inductively coupled plasma tandem quadrupole mass spectrometry after coprecipitation with magnesium hydroxide.

Coprecipitation with magnesium hydroxide was investigated as a pretreatment method for the determination of rare earth elements (REEs) in seawater samples, both for separation of the salt contents and for the enrichment of REEs. The precipitate of magnesium hydroxide was collected on a syringe filter and then subjected to the on-line measurement of REEs by an inductively coupled plasma tandem quadrupole mass spectrometer (ICP-MS/MS). Coprecipitation resulted in a separating rate of over 99% for salt contents, while the on-line measurement of REEs in the magnesium hydroxide provided an enhancement factor of 130-fold for the transient peak height of signal intensities. Mass-shift mode was applied to the measurement of REEs by ICP-MS/MS, where each isotope of the REEs was permitted to pass the first QMS and to react with oxygen gas in the reaction cell so as to form a monoxide ion, which was permitted to pass the second QMS and then measured by the detector. Mass-shift to monoxide ion effectively removed the spectral interferences in the measurement of REEs and permitted the correct determination of REEs in seawater samples. Detection limits were calculated based on the results of 10-set of the replicated blank test, which were low enough for the determination of REEs in natural seawater samples. The effectiveness of the present method was confirmed by the analysis of three certified reference materials of seawater, i.e. CASS-4, CASS-5, and NASS-6.

Development of an Automatic pH Adjustment Instrument for the Preparation of Analytical Samples Prior to Solid Phase Extraction.

An automatic pH adjustment instrument was developed for the preparation of analytical samples prior to solid phase extraction, which is widely used as a pretreatment technique for the separation of sample matrixes and preconcentration of elements for analysis. Real-time monitoring of the sample pH condition was performed by observing the light signal intensity of the pH-sensitive wavelength of the pH indicating reagent. A light of pH-insensitive wavelength was selected as the reference light to cancel the signal intensity variation of the pH-sensitive light due to the difference of pH indicating reagent concentration, possible difference in transparency of sample vessels, and minute fluctuation of the light source. The pH condition was elevated by automatic addition of ammonia solution using a nebulizer in the flow line of which an electromagnetic valve was equipped. Open and close operation of the electromagnetic valve was controlled based on the difference between the real-time pH condition and the target pH condition. The effectiveness of the instrument was confirmed by using various pH indicating reagents and by analyzing trace elements in a seawater certified reference material.

Calcium fluoride as a dominating matrix for quantitative analysis by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS): A feasibility study.

Calcium fluoride formed by the reaction between ammonium bifluoride and calcium chloride was investigated as a dominating matrix for quantitative analysis by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Transformation from a solid sample to the calcium fluoride-based matrix permitted quantitative analysis based on calibration standards made from elemental standards. A low abundance stable calcium isotope, i.e. 44Ca+, was monitored as the internal standard for quantitative analysis by LA-ICP-MS. Correlation coefficient factors for multiple elements were obtained with values over 0.999. The results for multiple elements in a certified reference material of soil (NIST SRM 2710a) agreed with the certified values in the range of expanded uncertainty, indicating the present method was valid for quantitation of elements in solid samples.

Automatic Preparation of Calibrating Solutions for Quantitative Analysis by ICP-MS.

An automatic system was developed to prepare calibrating solutions for elemental measurements by inductively coupled plasma mass spectrometry (ICP-MS). The flow-rates of diluting solution, internal standard solution, and initial elementals solution were monitored with a single ultrasonic flow sensor. Multiple calibrating solutions prepared by the present automatic system were analyzed by ICP-MS, whose results provided a correlation coefficient better than 0.999 for calibration curves. The results for multi-elements in a river-water certified reference material (NMIJ CRM 7202-b) agreed with the certified values.