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1.
Anal Chem ; 95(46): 16877-16884, 2023 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-37910825

RESUMO

In Ar-based inductively coupled plasma mass spectrometry (MS), Ar-related interference and the low ionization capacity of the Ar-ion source prevent facile and precise determination of certain elements. To address this problem, we investigated the application of microwave-induced plasma (MIP), and we improved its ionization capacity using He as the working gas. The MIP ion source was connected to a multicollector mass spectrometry (MC-MS) apparatus to improve the accuracy and precision of the isotopic analysis. A vacuum pump was used to achieve a low pressure (200-300 Pa) at the interface. The analytical figures of merit were discussed and evaluated by measuring the oxygen isotopes in oxygen. With the application of low-pressure He-MC-MIP-MS, the degree of ionization of oxygen could be significantly improved with He plasma. The interference of oxygen from the atmosphere could also be eliminated with low-pressure plasma, and the determination precision of oxygen isotopes could be improved with the application of MC-MS. Subsequently, using this method, 16O18O/16O16O was applied as the analytical ratio to investigate the interference, sensitivity, and precision. With this constructed method, the obtained long-term producibility of δ18O was 0.16‰ (2 SD), and the measured result for oxygen was consistent with that obtained by MAT 253 within the uncertainty limit. The development of low-pressure He-MC-MIP-MS can pave the way for the accurate measurement of nonmetal isotopes and easily interfered isotopes in Ar plasma.

2.
Rapid Commun Mass Spectrom ; 37(15): e9538, 2023 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-37184341

RESUMO

RATIONALE: Laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) has become a powerful technique for in situ Cu isotopic analysis in natural geological samples. Cu isotopic compositions in natural chalcopyrites have been used to reveal aspects of the mineralization processes directly. However, internationally or commercially available matrix-matched chalcopyrite reference materials for mass fractionation correction or quality control purposes are still lacking for in situ Cu isotopic analysis using LA-MC-ICP-MS. METHODS: Three natural chalcopyrites 14ZJ12-1, JGZ-29 and JGZ-78, and one copper metal GBW02141 with different Cu isotopic compositions were investigated as potential microanalytical reference materials by LA-MC-ICP-MS. Ga element was used as an internal standard to correct the mass fractionation of Cu isotopes during LA-MC-ICP-MS analysis. RESULTS: A large number of Cu isotope ratio measurements using femtosecond LA-MC-ICP-MS were conducted and produced good intermediate precision of δ65 CuNIST976 (0.07-0.08‰, 2 standard deviations), demonstrating the homogeneous Cu isotopic distribution in the recommended samples. The mean δ65 CuNIST976 values of -0.21 ± 0.04‰, 0.46 ± 0.04‰, -0.06 ± 0.04‰ and 0.11 ± 0.05‰ (2 standard deviations) in 14ZJ12-1, JGZ-29, JGZ-78 and GBW02141, respectively, were obtained using solution-MC-ICP-MS in the four recommended samples. CONCLUSIONS: Here, we describe three natural chalcopyrites 14ZJ12-1, JGZ-29, JGZ-78, and one copper metal GBW02141 as the potential Cu isotopic reference materials for LA-MC-ICP-MS analysis. Our analyses demonstrate that these recommended materials have a high degree of elemental and isotopic homogeneity, indicating that they are suitable for microanalysis techniques for data quality assurance or interlaboratory calibration.

3.
Proc Natl Acad Sci U S A ; 117(35): 21125-21131, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32817493

RESUMO

Zircons widely occur in magmatic rocks and often display internal zonation finely recording the magmatic history. Here, we presented in situ high-precision (2SD <0.15‰ for δ94Zr) and high-spatial-resolution (20 µm) stable Zr isotope compositions of magmatic zircons in a suite of calc-alkaline plutonic rocks from the juvenile part of the Gangdese arc, southern Tibet. These zircon grains are internally zoned with Zr isotopically light cores and increasingly heavier rims. Our data suggest the preferential incorporation of lighter Zr isotopes in zircon from the melt, which would drive the residual melt to heavier values. The Rayleigh distillation model can well explain the observed internal zoning in single zircon grains, and the best-fit models gave average zircon-melt fractionation factors for each sample ranging from 0.99955 to 0.99988. The average fractionation factors are positively correlated with the median Ti-in-zircon temperatures, indicating a strong temperature dependence of Zr isotopic fractionation. The results demonstrate that in situ Zr isotope analyses would be another powerful contribution to the geochemical toolbox related to zircon. The findings of this study solve the fundamental issue on how zircon fractionates Zr isotopes in calc-alkaline magmas, the major type of magmas that led to forming continental crust over time. The results also show the great potential of stable Zr isotopes in tracing magmatic thermal and chemical evolution and thus possibly continental crustal differentiation.

4.
Anal Chem ; 94(20): 7200-7209, 2022 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-35549212

RESUMO

In this study, we measure the absolute isotope ratios of ytterbium (Yb) by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) using an optimized regression model for mass bias correction. A rhenium (Re) reference material (NIST SRM 3143), which has been characterized previously, is selected as a primary calibrator to calibrate the absolute Yb isotope ratios for three Yb materials (GSB, Alfa Yb, and GBW). The three-isotope plot for all collected data indicates that the results of Yb isotope ratios obtained are not affected by any polyatomic interferences and the mass-independent isotopic fractionation. Furthermore, the recalibrated Hf historical isotope ratios by using the absolute Yb isotopic composition obtained in this study for the isobaric interference correction on Hf isotopes are in agreement with the original historical values. This work has further demonstrated the applicability of the regression model for the calibrated measurements of absolute isotope ratios using MC-ICP-MS. The three mono-elemental Yb standard solutions are thus proposed as the reference materials for Yb isotope ratio measurements in environmental and geoscience applications.


Assuntos
Isótopos , Itérbio , Isótopos/análise , Espectrometria de Massas/métodos , Análise Espectral
5.
Anal Chem ; 94(2): 1286-1293, 2022 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-34961322

RESUMO

Using boron as a test analyte, laser ablation (LA) solution sampling multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is proposed and validated as a fast method for isotopic analysis in natural liquids and digested samples without any prior purification process. We demonstrated that the solution reference standard can be used as a bracketing standard for in situ δ11B analysis in solids. Based on a sensitivity enhancement of 8- to 9-fold, all testing solutions were diluted in a 5% (v/v) NH3·H2O instead of classical 2% (v/v) HNO3. With a discrete and minimal sample solvent loading by the LA sampling strategy, it produces nearly "dry" plasma conditions that tolerate the sample matrix remarkably. The memory effect, one of the most difficult challenges in boron analysis, was dramatically eliminated with only 15 s wash time; thus, each analysis took less than 100 s. No significant matrix effects were observed for varying 50-100% boron concentrations in the samples and varying 20-60% NH3·H2O matrix used for the dilution, as well as for samples doped with a 1/100 synthetic seawater matrix. The external precision of δ11B measurements in NIST 951a was ± 0.30‰ (2SD). Good agreement with the values described in literature studies was achieved for δ11B measurements in eight geological reference materials, with precisions between 0.4 and 0.7‰ (2SD), confirming the accuracy of the proposed method. The proposed method offers advantages of simple sample preparation, fast analysis, and little use of chemical reagents.


Assuntos
Boro , Terapia a Laser , Boro/química , Espectrometria de Massas/métodos , Água do Mar , Manejo de Espécimes
6.
Anal Chem ; 91(13): 8109-8114, 2019 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-31199620

RESUMO

In this study, a simple and effective method for the simultaneous analysis of Cl, Br, and I in geological materials based on NH4HF2 digestion in open vessels (Savillex Teflon vials) is proposed. It is very interesting to note that Cl, Br, and I are not lost during NH4HF2 digestion at temperatures of 200-240 °C for 0.5-12 h in open vessels. This should be related to the alkaline atmosphere environment caused by the NH3 produced during NH4HF2 digestion, which suppresses the volatilization loss of Cl, Br, and I. A 100 mg sample of geological materials can be completely digested by using 400 mg of NH4HF2 at 220 °C for 2 h in Savillex Teflon vials. The use of new Savillex Teflon vials significantly reduced the procedural blanks of halogens compared with the old Savillex Teflon vials. The developed method was successfully applied to the simultaneous determination of Cl, Br, and I in a series of international geological reference materials. Most of the results were found to be in reasonable agreement with values reported in the literature. This simple, rapid, effective, and economical analytical method will significantly promote the development of halogen geochemistry.

7.
Anal Chem ; 90(15): 9016-9024, 2018 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-29986584

RESUMO

The U-Pb geochronologic analysis of accessory minerals has played an important role in Earth and solar system science in constraining the ages of a wide variety of rocks and minerals. Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) is one of the most popular techniques for U-Pb geochronologic analysis. Currently, the significant matrix effects observed between different accessory minerals and the lack of high-quality standards for many minerals of interest are the major limitations of its geochronological applications. In this study, we investigated the effects of the addition of oxygen, nitrogen, and water vapor before and after the ablation cell on the accuracy of the U-Pb dating of different minerals (e.g., zircon, monazite, titanite, and xenotime) by LA-ICP-MS. We found that the addition of water vapor, unlike that of oxygen and nitrogen, before the ablation cell can significantly suppress the matrix effects on U-Pb dating. The deviations of the measured 206Pb/238U ratios in these accessory minerals were significantly reduced from 10 to 24% to less than 1-2% when using NIST 610 glass as an external standard. This can be attributed to the suppression of elemental fractionation in both the laser ablation and ICP ionization processes by the presence of water vapor. The developed water vapor-assisted LA-ICPMS U-Pb dating method has been successfully applied to the analysis of zircon, monazite, xenotime, and titanite with NIST 610 glass as a reference material in both the 193 nm excimer laser and 213 nm Nd:YAG laser ablation systems.

8.
Anal Chem ; 88(20): 10088-10094, 2016 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-27628671

RESUMO

Sample preparation of whole-rock powders is the major limitation for their accurate and precise elemental analysis by laser ablation inductively-coupled plasma mass spectrometry (ICPMS). In this study, a green, efficient, and simplified fusion technique using a high energy infrared laser was developed for major and trace elemental analysis. Fusion takes only tens of milliseconds for each sample. Compared to the pressed pellet sample preparation, the analytical precision of the developed laser fusion technique is higher by an order of magnitude for most elements in granodiorite GSP-2. Analytical results obtained for five USGS reference materials (ranging from mafic to intermediate to felsic) using the laser fusion technique generally agree with recommended values with discrepancies of less than 10% for most elements. However, high losses (20-70%) of highly volatile elements (Zn and Pb) and the transition metal Cu are observed. The achieved precision is within 5% for major elements and within 15% for most trace elements. Direct laser fusion of rock powders is a green and notably simple method to obtain homogeneous samples, which will significantly accelerate the application of laser ablation ICPMS for whole-rock sample analysis.

9.
Guang Pu Xue Yu Guang Pu Fen Xi ; 36(11): 3683-8, 2016 Nov.
Artigo em Zh | MEDLINE | ID: mdl-30226688

RESUMO

A new sample fusion method for sulfides has been developed in this study. HNO3 was used as a short pre-oxidation reagent instead of the traditional solid oxidant (e.g., NaNO3, KNO3), which avoid the erosion of the platinum crucible. GeO2 was also added in samples to avoid the break of glass beads. The good analytical precisions of X-ray fluorescence spectrometry (RSD<5.6%, 1σ) and laser ablation inductivity coupled plasma mass spectrometry (RSD<3%, 1σ) demonstrated that the major elements were homogeneously distributed in the fused beads of sulfides. The determined major and minor elements (Si, Al, Fe, Mg, K, Ca, Na, Mn, Cu and Zn) values by using XRF and LA-ICP-MS are in excellent agreement with published values in three reference sulfide standards(reference values for Ti were absent). These results clearly demonstrate that the present fusion technique is well suitable for routine sulfide sample preparation for both XRF and LA-ICP-MS analysis.

10.
Anal Chem ; 87(2): 1152-7, 2015 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-25511501

RESUMO

A novel "wave" signal-smoothing and mercury-removing device has been developed for laser ablation quadrupole and multiple collector ICPMS analysis. With the wave stabilizer that has been developed, the signal stability was improved by a factor of 6.6-10 and no oscillation of the signal intensity was observed at a repetition rate of 1 Hz. Another advantage of the wave stabilizer is that the signal decay time is similar to that without the signal-smoothing device (increased by only 1-2 s for a signal decay of approximately 4 orders of magnitude). Most of the normalized elemental signals (relative to those without the stabilizer) lie within the range of 0.95-1.0 with the wave stabilizer. Thus, the wave stabilizer device does not significantly affect the aerosol transport efficiency. These findings indicate that this device is well-suited for routine optimization of ICPMS, as well as low repetition rate laser ablation analysis, which provides smaller elemental fractionation and better spatial resolution. With the wave signal-smoothing and mercury-removing device, the mercury gas background is reduced by 1 order of magnitude. More importantly, the (202)Hg signal intensity produced in the sulfide standard MASS-1 by laser ablation is reduced from 256 to 0.7 mV by the use of the wave signal-smoothing and mercury-removing device. This result suggests that the mercury is almost completely removed from the sample aerosol particles produced by laser ablation with the operation of the wave mercury-removing device. The wave mercury-removing device that we have designed is very important for Pb isotope ratio and accessory mineral U-Pb dating analysis, where removal of the mercury from the background gas and sample aerosol particles is highly desired. The wave signal-smoothing and mercury-removing device was applied successfully to the determination of the (206)Pb/(204)Pb isotope ratio in samples with low Pb content and/or high Hg content.

11.
Anal Chem ; 86(18): 9301-8, 2014 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-25162683

RESUMO

Silicon isotope ratios in natural waters and several commercial Si standards were determined by online ion exclusion chromatography (IEC) multicollector inductively couple plasma mass spectrometry (MC-ICPMS). As recent studies have shown that mass-independent fractionation (MIF) also exists in MC-ICPMS, e.g., Nd, Ce, W, Sr, Hf, Ge, Hg, and Pb isotopes, the nature of mass bias for Si isotopes was thus investigated. MIF was observed for Si isotopes on both Neptune and Neptune plus MC-ICPMS instruments in this study. Therefore, a standard-sample bracketing (SSB) mass bias correction model, capable of correcting both mass-dependent and mass-independent bias, was employed to obtain accurate Si isotope ratio results in all samples by using NBS28 Si standard as the bracketing standard. Medium resolution was used for all measurements in order to resolve polyatomic interferences on Si isotopes. NBS28 Si standard solutions prepared in nutrient-free seawater and 0.1% NaOH matrix, respectively, were used for the method validation and subjected to the online IEC MC-ICPMS determination of Si isotope ratios. Values of -0.01 ± 0.06 and 0.00 ± 0.06 ‰ (1 SD, n = 10) and -0.01 ± 0.03 and 0.01 ± 0.06 ‰ (1 SD, n = 10) for δ(29/28)Si and δ(30/28)Si, respectively, were obtained, confirming accurate results can be obtained using the reported method for natural waters. Significant variations in Si isotope ratios from -0.72 ± 0.09 to -0.24 ± 0.03 ‰ (1 SD, n = 10) and -1.36 ± 0.11 to -0.46 ± 0.04 ‰ (1 SD, n = 10) for δ(29/28)Si and δ(30/28)Si, respectively, were found among commercial Si standards of NIST SRM3150, SCP Si, and Sigma-Aldrich Si. Values of -0.06 ± 0.07 and -0.20 ± 0.11 ‰ (1 SD, n = 10) for δ(29/28)Si and δ(30/28)Si, respectively, were obtained for the MOOS-3 seawater whereas 0.59 ± 0.11 and 1.19 ± 0.15 ‰ (1SD, n = 10) for δ(29/28)Si and δ(30/28)Si, respectively, were obtained for the SLRS-5 river water. To the best of our knowledge this is the first report of an application of online IEC MC-ICPMS for the high accuracy and precision determination of Si isotope ratios in natural waters. The reported method provides for a relatively rapid (10 min per run) and simple online technique that requires no sample pretreatment for the Si isotope ratio measurements.

12.
Guang Pu Xue Yu Guang Pu Fen Xi ; 33(7): 1936-42, 2013 Jul.
Artigo em Zh | MEDLINE | ID: mdl-24059205

RESUMO

To improve the precision and accuracy of elements and isotopes analysis in traditional Ar-ICP, the addition of nitrogen in ICP has been widely used. The present review focused on the discussions of the basic physical and chemical properties of the Ar-N2 mixed gas inductively coupled plasma and the mechanisms of the special nature of Ar-N2 mixed gas plasma. The applications of Ar-N2 inductively coupled plasma in spectral analysis and mass spectrometry analysis in the past 40 years were summarized. The authors also give an overall outlook on the application of this technology.

13.
J Agric Food Chem ; 71(49): 19856-19865, 2023 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-38019292

RESUMO

Zinc (Zn) is an essential trace element in the human body, and its deficiency can seriously affect health. Agronomic Zn biofortification with ZnO nanoparticles (ZnO NPs) in consumable wheat prospectively relieves Zn deficiency. We developed an elemental quantitative imaging laser ablation-inductively coupled plasma optical emission spectrometry method to examine the distributions of Zn and other micronutrient elements in wheat grain and the endosperm. After foliar application of ZnO NPs (four rounds), Zn content in the endosperm can be significantly increased (221 ± 61%), and the Zn, Ca, Mg, and P content gradient decreased from the outside seed coat and aleurone layer to the endosperm, whereas the Fe, Mn, K, Cu, Sr, and Ba content gradient decreased from the crease region to the deeper endosperm. This may indicate how different elements enter the endosperm. Foliar application of ZnO NPs did not change the micronutrient accumulation pattern but did change their contents in wheat grain.


Assuntos
Terapia a Laser , Oligoelementos , Óxido de Zinco , Humanos , Óxido de Zinco/química , Endosperma/química , Triticum , Zinco/análise , Oligoelementos/análise , Grão Comestível/química , Análise Espectral
14.
Anal Chem ; 84(24): 10686-93, 2012 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-23176404

RESUMO

Complete sample digestion is a prerequisite for achieving reproducible and accurate analytical results for geological samples. Open-vessel acid digestions successfully dissolve mafic samples, but this method cannot achieve complete dissolution of felsic samples, because of the presence of refractory minerals such as zircon. In this study, an efficient and simplified digestion technique using the solid compound NH(4)HF(2) in a screw-top vial has been developed for multielement analysis of different types of rock samples. NH(4)HF(2) has a higher boiling point (239.5 °C) than conventional acids such as HF, HNO(3) and HCl, which allows for an elevated digestion temperature in open vessels, enabling the decomposition of refractory phases. Similar to HF, HNO(3) and HCl, ultrapure NH(4)HF(2) can be produced using a conventional PFA sub-boiling (heating and cooling) purification system. A digestion time of 2-3 h for 200 mg NH(4)HF(2) in a Savillex Teflon vial at 230 °C is sufficient to digest 50 mg of the felsic rock GSP-2, which is ~6 times faster than using conventional closed-vessel acid digestion at 190 °C (high-pressure PTFE digestion bomb). The price of a Savillex Teflon vial is far less than the price of a high-pressure PTFE digestion bomb (consisting of a PTFE inner vessel and an outer stainless steel pressure jacket). Moreover, the NH(4)HF(2)-open-vessel acid digestion is not hampered by the formation of insoluble fluorides. We have successfully applied the NH(4)HF(2)-open-vessel acid digestion to the digestion of a series of international geological reference materials, including mafic to felsic igneous rocks and shales. This method provides an effective, simple, economical, and comparatively safe dissolution method that combines the advantages of both the open- and closed-vessel digestion methods.

15.
Analyst ; 136(23): 4925-34, 2011 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-21881665

RESUMO

The influence of the addition of carbon using methane or methanol/water to an inductively coupled plasma (ICP) via the carrier gas flow on the sensitivity in laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was studied. During the ablation of SRM NIST 610 with simultaneous addition of CH(4) (0.6-1.4 ml min(-1)), a sensitivity enhancement of more than one order of magnitude for selected analytes (e.g. (75)As(+)) was observed. In addition to the sensitivity enhancement for As, Te, I and Se, also all other measured elements showed a significantly enhanced sensitivity (minimum by a factor of 2). Potential mechanisms for the observed intensity enhancement include charge transfer reactions, a change in the ICP shape and a temperature increase in the plasma. Furthermore, the aspiration of a methanol-water mixture into a cooled spray chamber and the simultaneous addition to the laser ablated aerosol was investigated. This type of mixing leads to a sensitivity enhancement up to a factor of 20. To prevent clogging of the sampler cone and skimmer cone by carbon deposition, a fast cleaning procedure for the interface is tested during running ICP, which allows the application of such a set-up for specific applications.

16.
Guang Pu Xue Yu Guang Pu Fen Xi ; 31(12): 3379-83, 2011 Dec.
Artigo em Zh | MEDLINE | ID: mdl-22295799

RESUMO

The 193 nm excimer laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used for the quantification of 13 elements (Li, B, Na, Mg, Al, K, Ca, Cr, Mn, Fe, Ni, Cu and Ba) in the plant samples (GBW070602, GBW070605 and GBW08514). Indium standard solution with known concentration was mixed into samples and used as an internal standard. Afterwards the samples were ground again and pressed to disks. NIST SRM 610 glass material reference standard was used as the external standard in the LA-ICP-MS measurements. In contrast to longer wavelength ablation techniques, in this experiment a round crater with low deposits could be achieved during ablation. And another study was done on the effect of homogenization over the powder disk It was clearly shown that the analytical results under the condition of 193 nm LA-ICP-MS, using NIST SRM 610 as the external standard for analysis of pressed disk of plant sample, are in good agreement with certified values.


Assuntos
Espectrometria de Massas , Plantas/química
17.
Waste Manag ; 86: 23-35, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30902237

RESUMO

Fly ash always contains many toxic elements which can be released into environment, thereby easily leading to environmental contaminations. In order to dispose fly ash safely, related strategies are needed. In this investigation, two kinds of hydroxylated calcined dolomites (HCD60 and HCD100) were used as the additives and compared with lime on the leachabilities of anionic species from fly ash. Both additives were found effective in reducing the leaching concentrations of these elements, which was better than that of only lime addition. Mg(OH)2 and MgO were believed to play important roles in the hydration reaction of fly ash. In the presence of Mg(OH)2 and MgO, there were more hydration products including calcium silicate hydrate, ettringite, hydrocalumite and other Layered double hydroxides (LDHs) generated which were effective candidates for anion removal. Thus, the final leaching results were controlled by these newly formed phases through adsorption, incorporation or encapsulation. On the other hand, compared with Mg(OH)2, MgO can promote the formation of hydration products in a larger extent because of the hydration process of MgO into Mg(OH)2. There was no systematic trend in the promotion of fly ash hydration by Mg(OH)2 or MgO because it had a close relationship with the properties of original fly ash. Objectively, hydroxylated calcined dolomites can be promising candidate additives for reduction of toxic elements leaching from fly ash.


Assuntos
Carbonato de Cálcio , Cinza de Carvão , Adsorção , Carbono , Hidróxidos , Magnésio
18.
J Hazard Mater ; 371: 474-483, 2019 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-30877864

RESUMO

Harmful trace elements, which are initially included in the coal fly ash, have the potential to be leached when coal fly ash comes in contact with water. This causes a risk of pollutant species being released, considering the long lifetime of building structures where coal fly ash was applied. Some Ca additives effectively function to suppress the release of anionic pollutants; however, the detailed suppression processes remains unclear. In this work, the influences of various Ca additives on the released anionic pollutants (B, F, S, As, and Cr) was systematically investigated. According to the comprehensive results of solution data with the solid characterization, the 60% hydroxylated calcined dolomite (HCD 60) was the best Ca additive for the suppression of different anionic pollutants since this Ca source not only simply provides an alkaline reagent but also supplies MgO and Mg(OH)2, which affect the phase transformation that accompanies with hydration. The phase transformation occurs from Ca(OH)2 to ettringite via hydrocalumite, which is the most important suppression processes of released pollutants. The precipitation of Ca salts is another pathway to immobilize these pollutants. In this scheme, MgO and Mg(OH)2 were proven to enhance the formation of ettringite and hydrocalumite, respectively.

19.
J Agric Food Chem ; 67(3): 935-942, 2019 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-30592410

RESUMO

A novel calibration strategy for the accurate determination of essential and toxic elements in both plant-based and animal-based foods was developed by synthesizing spiked agarose gels as matrix-matched external standards and carbon as the internal standard (IS). Aqueous solutions of agarose (4%, m/v) with defined amounts of the analytes were cast on a mold and then dried to form the agarose-gel standards. The spatial distributions of the analytes in the gel were examined using surface- and depth-mapping laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) protocols, and the gel homogeneity was found to be excellent (i.e., relative standard derivation <10%). Recovery of the 19 spiked elements in the gel standards was in the range of 86.9-94.7%. The limits of detection (LODs) ranged from 0.0005 (Rb) to 33.7 µg g-1 (S). Analysis results were in good agreement with certified values for various certified reference materials (CRMs). Furthermore, a porous rubber sample supporter was developed to improve the analysis throughput by about 3-fold.


Assuntos
Análise de Alimentos/métodos , Espectrometria de Massas/métodos , Oligoelementos/análise , Animais , Calibragem , Análise de Alimentos/normas , Espectrometria de Massas/normas , Carne/análise , Plantas/química , Padrões de Referência
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