Search

Mercury pollution is a critical, worldwide problem and the efficient, cost-effective removal of mercury from complex, contaminated water matrices in a wide pH range from strongly acidic to alkaline has been a challenge. Here, AlZn and AlFe alloys are investigated and a new process of synergistic reduction-amalgamation and in situ layered double hydroxide (SRA-iLDH) for highly efficient capture of aqueous Hg(Ⅱ) is developed using AlZn alloys. The parameters include the pH values of 1-12, the Hg(II) concentrations of 10-1000 mg L-1, and the alloy’s Zn concentrations of 20, 50 and 70% and Fe concentrations of 10, 20 and 50%. The initial rate of Hg(Ⅱ) uptake by AlZn alloys decreases with increasing Zn concentration while the overall rate is not affected. Specifically, AlZn50 alloy removes >99.5% Hg(Ⅱ) from 10 mg L-1 solutions at pH 1-12 in 5 min at a rate constant of 0.055 g mg-1 min-1 and achieves a capacity of 5000 mg g-1, being the highest value reported so far. The super-performance of AlZn alloy is attributed to multiple functions of chemical reduction, dual amalgamation, in situ LDH’s surface complexation and adsorption, isomorphous substitution and intercalation. This study provides a simple and highly efficient approach for removing Hg(Ⅱ) from complex water matrices.

Quantification of Cd

Hydrogen is becoming important clean energy while zerovalent iron (ZVI) and ferroferric oxide are of great interest to many applications including environmental remediation and chemical catalysis. Here, we report production of hydrogen, zerovalent iron and ferroferric oxide octahedron by etching Al–Fe alloys using NaOH solutions. The rate of hydrogen generation increased with increasing NaOH concentration and the alloy's particle size and decreasing the alloy's Fe concentration. Alkaline etching Al–Fe alloy particles of 425–850 μm produced 19–53 μm ZVI particles, which had paralleled ravines of 0.2–0.3 μm wide on the surface and possessed specific surface areas of 30–70 m2/g. The microscale ZVI was highly active for the removal of a model pollutant acid orange 7 from water. After 3–6 h ageing in the alkaline etching solution, the microscale ZVI particles were transformed to octahedral ferroferric oxide with saturation magnetization of 68.2 emu/g and residual magnetization of 13.2 emu/g and a coercive force of 330 Oe. This study provides a new approach for a facile synthesis of highly active ZVI and octahedral ferroferric oxide along with on-board generation of hydrogen from Al–Fe alloys.

Polybrominated diphenyl ethers (PBDEs) and their hydroxylated (OH-BDE) analogues are known as contaminants with potential risks to human health. In this work, a HPLC-ICP-MS method was developed for simultaneous determination of four polybrominated diphenyl ethers (BDE-47, −99, −153 and −209) and four hydroxylated analogues (3-OH-BDE-47, 5-OH-BDE-47, 6-OH-BDE-47, 5′-OH-BDE-99) in human serum. Solid-phase extraction (SPE) was employed as the primary extraction and purification procedure. By using mixtures of acetone and hexane with different rations, OH-PBDEs and PBDEs were efficiently recovered during elution procedure. With additional ultrasonic assisted extraction of PBDEs from solid residue after protein precipitation, the recoveries of investigated analytes ranged from 79.1 %to 89.9%. Due to the characteristics of inductively coupled plasma (ICP), organic matrix effects were effectively eliminated. Good sensitivity and precision were also obtained. The limits of quantification ranged from 0.060 to 0.081 ng mL−1 and inter-/intra-day relative standard deviations were all below 4%. In addition, compound-independent calibration (CIC) was investigated and the spray chamber efficiency might be a key factor for CIC application among different kinds of brominated chemicals. Finally, the developed method was successfully applied for analysis of 20 human serum samples collected from the Tianjin city. This work provided an alternative approach for simultaneous determination of halogenated chemicals by quantification of halogen element with one-time pretreatment, especially for human serum samples with limited sample volume.

Adsorption, sample preservation, and cross‐contamination are the major impediments to the accurate and sensitive analysis of low‐level mercury samples. Common measures to deal with this issue are to use Teflon, quartz, or borosilicate glass bottles for sampling, standard solution and sample preservation with oxidative chemicals, to prepare standard solutions daily and to use dedicated glassware. This paper demonstrates that these measures are neither efficient nor effective. Two common laboratory sample containers (borosilicate volumetric glass flasks and polypropylene tubes) are investigated for the preparation and preservation of water samples and standard solutions of 0.2–1 µg L−1 with 2% HNO3. Mercury adsorption rates of 6–22% are observed within 30 min and after 48 days, the adsorption is greater than 98%. In stark contrast, no adsorption is found during a testing period of 560 days when the solutions are subject to potassium permanganate‐persulfate digestion. New glass flasks and polypropylene bottles are free of mercury contamination but reused flasks are a major source of mercury cross‐contamination. To minimize adsorption and cross‐contamination, standard solutions are treated by potassium permanganate‐persulfate or BrCl digestion, and each individual sample and standard solution should be stored and prepared in single‐use polypropylene bottle, without transference., Adsorption and cross‐contamination are the major challenges for accurate analysis of trace mercury. This study demonstrates that adsorption is the root cause for cross‐contamination, and single use of polypropylene plastic bottles for sample preparation and storage is highly efficient to completely solve these notorious problems as long as sample and standard solutions are subject to potassium permanganate‐persulfate digestion.

Liver plays a major role in metabolism and acts as a source of energy for the body by storing glycogen. With the growing interest and investigation in the biological effects in recent years, it is important and necessary to develop accurate and comparable analytical methods for elements in bio-samples. It has, however, been 10 years since the tissue sample (bovine liver) of CCQM-K49 key comparison. The purpose of CCQM-K145 is to ensure the comparable and traceable measurement results for essential and toxic elements such as P, S, Zn, Mn, Ni, Mo, Sr, Cr, Co, Pb, As and Hg in bovine liver among NMIs and other designated measurement bodies worldwide. The comparison was agreed by IAWG as 6th IAWG Benchmarking Exercise with Zn and Ni as exemplary elements at the meeting in Korea in the early October 2016. The results of CCQM-K145 are expected to cover the measurement capability and support CMCs claiming for inorganic elements in the similar biological tissue materials and food samples. 30 NMIs and DIs registered in CCQM-K145. With respect to the methodology, a variety of techniques such as IDMS, ICP-OES, ICP-MS(non-ID), AAS and NAA were adopted by the participants. For Zn, Ni, Sr, Pb and Hg measurements, most participants chose ID-ICP-MS method, which showed the better performance in terms of consistency and reliability of the measurement results. In aspect of the traceability for the measurement results in CCQM-K145, most participants used their own (in house) CRMs or other NMI's CRMs to guarantee trace to SI unit. Most participants used similar matrix CRMs for quality control or method validation. Base on different statistic way to calculate the reference mass fraction values and associated uncertainties for each measurand, removal of the suspected extreme values, and discussion at the IAWG meetings, the median values are proposed as the KCRV for Zn, Ni, Mn, Mo, Cr, Pb and Hg; the arithmetic mean values are proposed as the KCRV for P, S, Sr, Co and As. In general, the performances of the majority of CCQM-K145 participants are very good, illustrating their measurement capabilities for Zn, Ni, P, S, Mn, Mo, Sr, Cr, As, Co, Pb and Hg in a complex biological tissue matrix. Bovine liver contains many kinds of nutrients and microelements, it can be regarded as a typical representative material of biological tissue and food. In CCQM-K145, the analytes involved alkali metals and transition elements, metalloids / semi-metals and non metals with a range of mass fraction from mg/g to μg/kg. CCQM-K145 also tested the ability of NMIs/DIs to determine elements that were easy to be lost and polluted, and interfered significantly. The chemical pretreatment methods of samples used in the comparison is suitable for general food and biological matrix samples. A variety of measurement methods used in the comparison represent the main instrumental technology for elemental analysis. Therefore, for supporting CMC claim, CCQM-K145 is readily applicable to measurement of more elements in a wide range of biological materials (including liquids and solids) and meat products. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

In situ remediation of groundwater by zerovalent iron (ZVI)-based technology faces the problems of rapid passivation, fast agglomeration, limited range of pollutants and secondary contamination. Here a new concept of Magnesium–Aluminum (Mg–Al) alloys and in situ layered double hydroxides on is proposed for the degradation and removal of a wide variety of inorganic and organic pollutants from groundwater. The Mg–Al alloy provides the electrons for the chemical reduction and/or the degradation of pollutants while released Mg 2+, Al 3+ and OH - ions react to generate in situ LDH precipitates, incorporating other divalent and trivalent metals and oxyanions pollutants and further adsorbing the micropollutants. The Mg–Al alloy outperforms ZVI for treating acidic, synthetic groundwater samples contaminated by complex chemical mixtures of heavy metals (Cd 2+, Cr 6+, Cu 2+, Ni 2+ and Zn 2+), nitrate, AsO 3 3-, methyl blue, trichloroacetic acid and glyphosate. Specifically, the Mg–Al alloy achieves removal efficiency ≥99.7% for these multiple pollutants at concentrations ranging between 10 and 50 mg L −1 without producing any secondary contaminants. In contrast, ZVI removal efficiency did not exceed 90% and secondary contamination up to 220 mg L −1 Fe was observed. Overall, this study provides a new alternative approach to develop efficient, cost-effective and green remediation for water and groundwater.

A simple indirectly competitive ratiometric fluorescent immunoassay was designed based on fluorescein amidite (FAM)-DNA–functionalized CdSe/ZnS quantum dots (QDs) for the sensitive determination of tetrabromobisphenol A (TBBPA). At the detection system, catalase (CAT) was labeled on the secondary antibody (Ab2), which served as a controller of the H2O2 concentration. After the competitive binding step, the emitted red fluorescence (excitation at 490 nm) from FAM-DNA–functionalized CdSe/ZnS QDs could be effectively quenched by the H2O2 added. Under the optimized conditions, the limit of detection (LOD) reached 0.118 μg/L with a linear range of 0.34–45.34 μg/L, which was approximately 1 order of magnitude lower than that by HRP-based traditional ELISA. Furthermore, the combination of the dual-output ratiometric fluorescence assays with ELISA improved the inherent built-in rectification to the environment, which brought about satisfactory accuracy and precision (recoveries, 83.16–112.4%; CV, 2.42–7.28%), indicating great potential for the determination of trace TBBPA from food and environmental samples.

Groundwater contamination is a worldwide concern and the development of new materials for groundwater remediation has been of great interest. This study investigated removal kinetics and mechanisms of nitrate, copper ion and hexavalent chromium (20–50 mg L−1) by particles of Al-Fe alloy consisting of 20% Fe in batch reactors from a single KNO3, CuSO4, Cu(NO3)2, K2Cr2O7 and their mixed solutions. The effects of contaminant interactions and initial pH of the solution were examined and the alloy particles before and after reaction were characterized by X-ray diffraction spectrometer, scanning electron microscopy and X-ray photoelectron spectroscopy. The removal mechanisms were attributed to chemical reduction [Cu(II) to Cu, NO3− to NH3 and Cr(VI) to Cr(III)] and co-precipitation of Cr(III)-Al(III)-Fe(III) hydroxides/oxyhydroxides. Cu(II) enhanced the rates of NO3− and Cr(VI) reduction and Cr(VI) was an inhibitor for Cu(II) and NO3− reduction. This study demonstrates that Al-Fe alloy is of potential for groundwater remediation.

A simple and practical magnetic solid-phase extraction high-performance liquid chromatography-inductively coupled plasma mass spectrometry (MSPE-HPLC-ICP-MS) method for extraction and determination of trace mercury species, including inorganic mercury (IHg), monomethylmercury (MeHg) and ethylmercury (EtHg), was developed. The MSPE adsorbent, urchin-like thiol and thioether-functionalized magnetic covalent organic frameworks (Fe3O4@COF-S-SH), was synthesized by coating covalent organic frameworks (COFs) on the surface of Fe3O4 nanoparticles at room temperature and then easily grafting 1,2-Ethanedithiol on the COFs. The as-prepared Fe3O4@COF-S-SH has strong adsorption capacity for IHg, MeHg and EtHg, with excellent static adsorption capacity: 571, 559 and 564 mg g-1, respectively. The parameters influencing the extraction and enrichment had been optimized, including pH, adsorption and desorption time, composition and amount of the eluent, co-existing ions and dissolved organic materials etc. Under the optimized condition, the limit of detection (3δ) of the proposed method were 0.96, 0.17 and 0.47 ng L-1 for IHg, MeHg and EtHg, and the developed method has high actual enrichment factors of 370, 395, 365-fold for IHg, MeHg and EtHg based on 200 mL samples, respectively. The high accuracy and reproducibility has been proved by the spiked recoveries (96.0‒108 %) in real water samples and determination of the certified reference material. Both the adsorption and desorption process can be completed within 5 min. The proposed method with simple operation, short pre-concentration time and high sensitivity has been successfully applied to mercury speciation at trace levels in the samples with complicated matrices, including underground water, surface water, sea water and fish samples.

Nano zero-valent iron (NZVI) particles have been extensively investigated for nitrate reduction in water. However, the reduction by NZVI requires acidic pH conditions and the final product is exclusively ammonium, leading to secondary contamination. In addition, nanomaterials have potential threats to environment and the transport and storage of nanomaterials are of safety concerns. Aluminum, the most abundant metal element in the earth's crust, is able to reduce nitrate, but the passivation of aluminum limits its application. Here we report Al alloys (85% Al) with Fe, Cu or Si for aqueous nitrate reduction. The Al alloys particles of 0.85-0.08 mm were inactivate under ambient conditions and a simple treatment with warm water (45 °C) quickly activated the alloy particles for rapid reduction of nitrate. The Al-Fe alloy particles at a dosage of 5 g/L rapidly reduced 50 mg-N/L nitrate at a reaction rate constant (k) of 3.2 ± 0.1 (mg-N/L)1.5/min between pH 5-6 and at 4.0 ± 0.1 (mg-N/L)1.5/min between pH 9-11. Dopping Cu in the Al-Fe alloy enhanced the rates of reduction whereas dopping Si reduced the reactivity of the Al-Fe alloy. The Al alloys converted nitrate to 20% nitrogen and 80% ammonium. Al in the alloy particles provided electrons for the reduction and the intermetallic compounds in the alloys were likely to catalyze nitrate reduction to nitrogen.

The CCQM-K88 key comparison was organised by the Inorganic Analysis Working Group of CCQM to test the abilities of the national metrology institutes to measure the mass fraction of lead in lead-free solder containing silver and copper. National Metrology Institute of Japan (NMIJ), National Institute of Metrology P. R. China (NIM) and Korea Research Institute of Standards and Science (KRISS) acted as the coordinating laboratories. The participants used different measurement methods, though most of them used inductively coupled plasma optical emission spectrometry (ICP-OES) or isotope-dilution inductively coupled plasma mass spectrometry (ID-ICP-MS). Accounting for relative expanded uncertainty, comparability of measurement results was successfully demonstrated by the participating NMIs for the measurement of the mass fraction of lead in lead-free solder at the level of 200 mg/kg. It is expected that metals at mass fractions greater than approximately100 mg/kg in lead-free solder containing silver and copper can be determined by each participant using the same technique(s) employed for this key comparison to achieve similar uncertainties mentioned in the present report. Fil: Hioki, Akiharu. National Metrology Institute of Japan (NMIJ); Japón Fil: Nonose, Naoko. National Metrology Institute of Japan (NMIJ); Japón Fil: Liandi, Ma. National Institute of Metrology (NIM); China Fil: Jingbo, Chao. National Institute of Metrology (NIM); China Fil: Liuxing, Feng. National Institute of Metrology (NIM); China Fil: Chao, Wei. National Institute of Metrology (NIM); China Fil: Cho, Kyung Haeng. Korea Research Institute of Standards and Science (KRISS); Corea del Sur Fil: Suh, Jung Ki. Korea Research Institute of Standards and Science (KRISS); Corea del Sur Fil: Min, Hyung Sik. Korea Research Institute of Standards and Science (KRISS); Corea del Sur Fil: Lim, Youngran. Korea Research Institute of Standards and Science (KRISS); Corea del Sur Fil: Recknagel, Sebastian. Federal Institute for Materials Research and Testing (BAM); Alemania Fil: Koenig, Maren. Federal Institute for Materials Research and Testing (BAM); Alemania Fil: Vogl, Jochen. Federal Institute for Materials Research and Testing (BAM); Alemania Fil: Caciano de Sena, Rodrigo. Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMetro); Brasil Fil: dos Reis, Lindomar Augusto. Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMetro); Brasil Fil: Borinsky, Mónica. Instituto Nacional de Tecnología Industrial (INTI); Argentina Fil: Puelles, Mabel. Instituto Nacional de Tecnología Industrial (INTI); Argentina Fil: Hatamleh, Nadia. Instituto Nacional de Tecnología Industrial (INTI); Argentina Fil: Acosta, Osvaldo. Instituto Nacional de Tecnología Industrial (INTI); Argentina Fil: Turk, Gregory. National Institute of Standards and Technology (NIST); Estados Unidos Fil: Rabb, Savelas. National Institute of Standards and Technology (NIST); Estados Unidos Fil: Sturgeon, Ralph. National Research Council (NRC); Canadá Fil: Methven, Brad. National Research Council (NRC); Canadá Fil: Rienitz, Olaf. Physikalisch-Technische Bundesanstalt (PTB); Alemania Fil: Jaehrling, Reinhard. Physikalisch-Technische Bundesanstalt (PTB); Alemania Fil: Konopelko, L. A. D. I. Mendeleev Institute for Metrology (VNIIM); Rusia Fil: Kustikov, Yu. A. D. I. Mendeleev Institute for Metrology (VNIIM); Rusia Fil: Kozyreva, S. B. D. I. Mendeleev Institute for Metrology (VNIIM); Rusia Fil: Korzh, A. A. D. I. Mendeleev Institute for Metrology (VNIIM); Rusia

The supplementary comparison APMP.QM-S5 was undertaken to demonstrate the capability of participating national metrology institutes (NMIs) and designated institutes (DIs) in measuring the contents of the incurred essential elements (iron and zinc) and toxic elements (total arsenic and cadmium) at ?g/g levels in a test sample of dried shrimp by various analytical techniques. At the APMP TCQM Meeting held in Pattaya, Thailand in November 2010, Government Laboratory of the Government of the Hong Kong Special Administrative Region (GLHK) proposed this APMP supplementary comparison. The proposal was further discussed and agreed upon at the CCQM Inorganic Analysis Working Group Meeting held in Paris in April 2011. GLHK was the coordinating laboratory for the supplementary comparison. For enhancing the collaboration amongst specialized regional bodies in Asia-Pacific and to help build the laboratory capacity of NMIs/DIs from developing economies, the reference values of the supplementary comparison are used for evaluation of performance of participants of an APMP proficiency testing programme (APMP PT 11-01), an Asia-Pacific Laboratory Accreditation Cooperation proficiency testing programme (APLAC T082) and an Asia-Pacific Economic Co-operation proficiency testing programme (APEC PT), which were concurrently run using the same testing material as in APMP.QM-S5. The supplementary comparison serves to facilitate claims by participants on the Calibration and Measurement Capabilities (CMCs) as listed in Appendix C of the Key Comparison Database (KCDB) under the Mutual Recognition Arrangement of the International Committee for Weights and Measures (CIPM MRA). A total of 18 institutes registered for the supplementary comparison and all of them submitted their results. Most of the participants used microwave acid digestion methods for sample dissolution. For the instrumental determination, a variety of techniques like ICP-MS, ICP-OES, INAA and AAS were employed by the participants. For this supplementary comparison, inorganic core capabilities have been demonstrated by concerned participants with respect to methods including ICP-MS (without isotope dilution), ID-ICP-MS, ICP-OES, INAA and AAS on the determination of total arsenic, cadmium, iron and zinc in a matrix of seafood. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the APMP, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Several analytical techniques are currently used to eliminate the matrix effect in the determination of lead by Isotope dilution mass spectrometry (IDMS), which include using admixed Tl for “external normalization” and the separation of Pb from the sample. Unfortunately, because of the different performance of Pb and Tl, and the complex separation process or “column matrix effect”, it is often a considerably more difficult matter to totally eliminate the matrix effects during lead analysis by IDMS. In this study, a method to quantify the matrix effect is presented in the analysis of lead in soldering tin sample by ICP-IDMS. Moreover, sample separation process was also carried out followed by ICP-IDMS analysis using standard-sample bracketing (SSB) correction. The consistent results of the two processes proved the validity of the matrix quantification method, and this idea will help to get precise measurements of Pb isotope abundances.

In this key comparison anion calibration solutions of nitrate and nitrite were investigated. The mass fractions of the anions in both solutions were about 1 g/kg. For the nitrate comparison 8 participants provided results; 3 analytical techniques were used: ion chromatography, capillary electrophoresis and coulometry after ion exchange. The nitrite amount content was determined by 7 participants using one of the following 3 techniques: ion chromatography, titrimetry and capillary electrophoresis. The following institutes participated in this key comparison: INTI (Argentina), KRISS (Korea), LNE (France), NIM (Pepole's Republic of China), NIST (USA), NMIJ (Japan), SMU (Slovakia) and VNIIM (Russia). The variability (RSD) of the results is about 0.75% for both the nitrite and the nitrate solutions. Compared to the key comparison CCQM-K29 the results of CCQM-K59 were significantly worse. This is in part due to the measurement methods used, possibly also due to the standards used by the institutes. A pilot study (P89) was performed in parallel on the same calibration solutions used in this K59 comparison study by laboratories preferring to participate in the pilot study and on a seawater sample containing about 0.1 mg/kg nitrite and 1 mg/kg nitrate. The results of the pilot study are reported separately. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).