Ion Chromatography-inductively Coupled Plasma Mass Spectrometry Research Articles

Germanium speciation study in soil from an electronic waste processing plant area

PurposeGermanium (Ge) is known as a Technology Critical Element (TCE) and has been widely used in electronic and industrial products. Waste electronic and electrical equipment (WEEE) containing germanium goes to WEEE treatment plants. The transfer of Ge in the environment makes it necessary to get to know its mobility, reactivity, and chemical transformations in soil. The objective of this research was to develop a methodology for germanium speciation in soil under pressure from storage, processing, and recovery from electrowaste.Materials and methodsThirty soil cores (30 cm long) were collected from an area around a WEEE plant, using a Humax soil sampler. Soil magnetometry methods were used for the first time during the determination of soil sampling points for germanium. After basic physicochemical analysis (pH, Eh, total element concentration using the ICP-MS technique), soil samples were prepared for germanium speciation. The optimisation and validation of a methodology for determining Ge species in easily-leached fractions of soil collected from areas around an electrowaste plant, was studied using Ion Chromatography-Inductively Coupled Plasma-Mass Spectrometry (IC-ICP-MS). Chromatographic conditions were optimised, taking soil matrix effects into account. Optimised Ge extraction from the soil included: extraction time, type of extractants, extraction support using shaking, and ultrasound.Results and discussionThe Ge species (Ge(IV), monomethylgermanium (MMGe), and dimethylgermanium (DMGe)) were successfully separated after 12 min on a Dionex IonPac AS9-HC column with ammonium nitrate and potassium sodium tartrate as an elution phase. The highest extraction efficiency was achieved by using 100 mM NH4NO3 with 1 mM potassium sodium tartrate as an extractant, that washes out Ge from soils within 4 h. In most cases, the soils contained a Ge(IV) form. Germanium methyl derivatives were only found in a few soil samples. Our research showed that germanium concentration in the studied area was as high as 7.64 mg.kg−1, with an average concentration of 3.51 mg.kg−1. The results allowed the creation of a correlation matrix, which identified many strong correlations.ConclusionThis research confirmed the impact of a WEEE plant on the increase of the Ge content in topsoil, when in direct proximity. Increased germanium content occurred in soil samples located north of the emitter, which is consistent with the prevailing wind direction. The study confirmed that the soil magnetometry method is applicable for detecting TCE. Soil samples with the highest content of germanium had a very high magnetic susceptibility and there is a correlation between these parameters.

Pollution Levels for Airborne Hexavalent Chromium of PM2.5 in Typical Cities of China

As a carcinogenic pollutant, hexavalent chromium (Cr(VI)) in the ambient air has serious influences on public health. Due to its instability and difficulty in chemical analysis, few studies have been conducted on the regional concentration level of environmental Cr(VI), especially in China. The pollution levels of Cr(VI) in ambient PM2.5 were determined in two sampling sites of Beijing and Qingdao from September to December 2020. The concentrations of Cr(VI) were determined using Ion Chromatography-inductively coupled plasma mass spectrometry(IC-ICP-MS), and the Cr concentrations were simultaneously analyzed by Inductively Coupled Plasma-atomic emission spectrometry(ICP-AES). The main results are as follows: (1) Based on the analysis of samples collected at the sampling sites of Beijing and Qingdao, the concentrations of Cr(VI) in PM2.5 were (0.140 ± 0.065) ng/m3 and (0.091 ± 0.073) ng/m3, respectively; (2) During the sampling period, the mean ratio of Cr(VI) to Cr was (0.0623 ± 0.0969). The ratio of Cr(VI)/Cr in Beijing and Qingdao were 0.076 ± 0.104 and 0.041 ± 0.039, respectively. In conclusion, compared with other countries, the concentration of Cr(VI) at the sampling sites of Beijing and Qingdao showed lower values. The average concentration of Cr(VI) estimated by the ratio of this research in China is lower than that in South Korea and similar to those in Canada and Australia.

Facile Lego-Spinner Pretreatment Device for Analysis of Arsenic Species in Dried Blood Spots by Ion Chromatography-Inductively Coupled Plasma-Mass Spectrometry.

Dried blood spot (DBS) detection has the advantages of small blood collection, convenience, and reliability, which provides a possibility for large-scale evaluation of arsenic exposure in human population. Herein, a facile Lego-spinner pretreatment device is rationally designed for speciation analysis of arsenic in DBSs by ion chromatography-inductively coupled plasma-mass spectrometry (IC-ICP-MS). In the mixing mode of the Lego-spinner, the magnetic stir bar in the centrifuge tube rotates under a magnetic field to assist the dispersive extraction of arsenic species in the DBS with reagents. In the centrifugation mode of the Lego-spinner, the arsenic extract is separated from the blood matrix for the subsequent IC-ICP-MS analysis. For the DBS prepared from 80 μL of whole blood, the whole pretreatment operation can be completed within 25 min. The detection limits of arsenobetaine, arsenite, dimethylarsenate, monomethylarsonate, and arsenate in the DBS are 0.09-0.15 μg L-1, and precisions are <11%. The concentrations of these five arsenic species are highly correlated between whole blood and the DBS (r2 > 0.97), and Bland-Altman analysis indicates that the concentration difference of arsenic species between whole blood and the DBS is within ±20%. The DBS sampling approach can effectively preserve arsenic species for at least 30 days at 4 °C, and the contents of arsenic species in the DBS prepared from capillary blood are in a reasonable agreement with those of venous whole blood (gold standard). This Lego-spinner provides a handy and efficient tool for fast extraction of arsenic species in DBSs, facilitating the in-depth study of arsenic migration and transformation in the human body.

Comparison of Ion Chromatography Conductivity Detection (IC-CD) and Ion Chromatography Inductively Coupled Plasma Mass Spectrometry (IC-ICP-MS) for the Determination of Phosphonic Acid in Grapevine Plant Parts, Wine, and Soil.

Potassium dihydrogen phosphonate had been allowed as a plant strengthener in organic viticulture in the European Union only until 2013, supporting the control of grapevine downy mildew. Therefore, low or nondetectable levels are a prerequisite for marketing of organic wines and, consequently, validated analytical methods are of major interest. Herein, two methods based on ion chromatography conductivity detection (IC-CD) or ion chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS) for the determination of phosphonic acid (H3PO3) from 14 different plant matrices of Vitis vinifera L., wine, and soil were developed, validated, and compared. Extraction recoveries ranged from 95.1 to 99.3%. Limits of quantification (LOQ) ranged in liquid and solid samples from 3.8 to 16.8 μg/kg and 0.08 to 2.41 mg/kg for ICP-MS detection and from 39.9 to 593.7 μg/kg and 3.51 to 58.7 mg/kg for CD, respectively. Data on a current anonymized selection of 100 conventionally and 30 organically produced wines are briefly presented to demonstrate the suitability of the method.

Quantitative extraction of chromium VI and III from tanned leather: a comparative study of pretreatment methods

In this study, seven pretreatment methods for chromium speciation in tanned leather were evaluated: acidic mineralization, ethylenediaminetetraacetic acid (EDTA) extraction, diethylenetriaminepentaacetic acid (DTPA) extraction, alkaline extraction (NH4OH), ammonium nitrate extraction (NH4NO3), water extraction, and phosphate buffer extraction. Acidic mineralization permitted the decomposition of the organic matter and ensured the complete digestion of leathers, giving access to the total content of chromium in each sample using inductively coupled plasma-atomic emission spectrometry (ICP-AES). From all the extractant media tested, EDTA proved to be the most efficient, allowing the extraction of Cr(VI) and Cr(III) as a Cr(III)-EDTA complex, quantitatively. Method validation is presented for EDTA extraction and direct mineralization. For the EDTA extraction, method detection limit (MDL) and method quantification limit (MQL) for total Cr in leather were 3.4 ppb and 11.2 ppb (µg of total Cr per L of extraction solution), respectively. Due to the lack of leather certified reference materials (CRMs) for Cr(VI), accuracy was evaluated by spiking leather samples with a Cr(VI) solution. The spike recovery of EDTA microwave assisted extraction ranged from 91.0 to 108.6%. Interday precision was also evaluated and all variation coefficients were below 5%, for both mineralization and EDTA extraction. This article provides an efficient procedure to extract quantitatively chromium from leather, while maintaining the speciation, which can be further followed by ion chromatography-inductively coupled plasma-mass spectrometry (IC-ICP-MS).

A Novel Pretreatment Device Integrating Magnetic-Assisted Dispersive Extraction and Ultrasonic Spray Separation for Speciation Analysis of Arsenic in Whole Blood by Ion Chromatography-Inductively Coupled Plasma-Mass Spectrometry.

Speciation analysis of arsenic in blood is essential for identifying and quantifying the exposure of arsenic and studying the metabolism and toxicity of arsenic. Herein, a novel pretreatment device is rationally designed and used for speciation analysis of arsenic in whole blood by ion chromatography-inductively coupled plasma-mass spectrometry (IC-ICP-MS). The sample centrifuge tubes containing blood, reagents, and a magnetic stir bar are placed on the fidget spinner of the pretreatment device. When flicking the fidget spinner rotation with the finger, the magnetic stir bar in the tube rotates in three dimensions under the magnetic field, thereby assisting dispersive extraction of arsenic species by the mixing of blood with reagents. Afterward, the arsenic extract is separated in situ from the blood matrix using an ultrasonic spray sheet covered with a filter and ultrafiltration membrane, which is directly used for subsequent IC-ICP-MS analysis. For 100 μL of blood, the whole pretreatment operation can be completed within 10 min. With As(III), As(V), MMA, and DMA in blood as analytes, the use of the present pretreatment device will hardly lead to the loss and transformation of arsenic species, and the extraction efficiency of the total arsenic is more than 96%. When the pretreatment device is coupled to IC-ICP-MS, the detection limits of four arsenic species in whole blood are 0.017-0.023 μg L-1, and precisions are within 2.3-4.2%. This pretreatment device provides a simple, fast, efficient, and low-cost tool for extraction and separation of arsenic species in whole blood, opening a new idea for the pretreatment of complex samples.

Feasibility of quantitative inorganic arsenic speciation at the parts-per-trillion level using solid phase extraction and femtosecond laser ablation inductively coupled plasma mass spectrometry

Toxicity of arsenic compounds depends on the chemical structure as well as the concentration. Thus, separation of the toxic arsenic species should precede the quantification for the accurate toxicity assessment. Ion chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS) has been the most popular method for separation and quantification of toxic arsenic species. However, the method requires complex instrument, elaborate sample preparation, and long analysis time. In this work, toxic inorganic arsenic species in water was separated by the simple solid phase extraction (SPE) using a strong anion-exchange membrane filter, and then the membrane filter was analyzed by femtosecond laser ablation inductively coupled plasma mass spectrometry (fs-LA-ICP-MS). The pH value of the sample was adjusted to 4 using ammonium hydroxide and phosphoric acid for the complete separation of the toxic inorganic arsenic from the other organic arsenics. The linear dynamic range was from 0.5 to 1000 μg/kg, and the correlation coefficient was 0.99989. The recovery efficiency was 96‑106%. The detection limit of the inorganic arsenic was 0.028 μg/kg. Our results indicate that SPE-fs-LA-ICP-MS provides enough analytical performance to analyze the toxic inorganic arsenic in water at the level of parts per trillion using the simple separation method and the rapid laser ablation sampling.

Development of a Tellurium Speciation Study Using IC-ICP-MS on Soil Samples Taken from an Area Associated with the Storage, Processing, and Recovery of Electrowaste.

The optimization and validation of a methodology for determining and extracting inorganic ionic Te(VI) and Te(IV) forms in easily-leached fractions of soil by Ion Chromatography-Inductively Coupled Plasma-Mass Spectrometry (IC-ICP-MS) were studied. In this paper, the total concentration of Te, pH, and red-ox potential were determined. Ions were successfully separated in 4 min on a Hamilton PRPX100 column with 0.002 mg/kg and 0.004 mg/kg limits of detection for Te(VI) and Te(IV), respectively. Soil samples were collected from areas subjected to the influence of an electrowaste processing and sorting plant. Sequential chemical extraction of soils showed that tellurium was bound mainly with sulphides, organic matter, and silicates. Optimization of soil extraction allowed 20% average extraction efficiency to be obtained, using 100 mM citric acid as the extractant. In the tested soil samples, both tellurium species were present. In most cases, the soils contained a reduced Te form, or the concentrations of both species were similar.

Quantitative selenium speciation in feed by enzymatic probe sonication and ion chromatography-inductively coupled plasma mass spectrometry

ABSTRACT A rapid, sensitive and species preservative analytical method for the simultaneous determination of six selenium (Se) species has been developed. Enzymatic probe sonication (EPS) was investigated as a novel and alternative technology for the extraction of Se species from feed matrices and the results were compared with the conventional hot water extraction, enzymatic hydrolysis and sequential extraction. The critical parameters of EPS such as enzyme types, extraction time, temperature, ultrasonic power and sample/enzyme ratio were varied with control. The Se species were separated and quantitatively determined by ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS). Under current optimised conditions, six inorganic and organic Se species were completely separated within 15 min in a single chromatographic run. The spectral interferences from the argon plasma 40Ar2, 40Ar37Cl or 1H79Br were effectively removed by employing the kinetic energy discrimination (KED) mode. Quantitative extraction for total Se (>94.8%) and more than 89.0% for the sum of different Se chemical forms without species transformation were obtained in only 60 s by applying the EPS treatment using aqueous protease XIV. The limits of detection (LODs) and quantification (LOQs) for Se species were in the ranges of 0.21–0.56 µg kg–1 and 0.69–1.87 µg kg–1, respectively. The proposed method was successfully applied to the speciation of Se in several reference materials and feed samples collected from the markets and local farms.

A universal method for the speciation analysis of arsenic in various seafood based on microwave-assisted extraction and ion chromatography-inductively coupled plasma mass spectrometry

The speciation analysis of arsenic in seafood is of great significance for objectively and scientifically assessing arsenic health risks in seafood. In general, different types of seafood contain a variety of different arsenic species and have quite different matrix. Thus, the detection of arsenic species in different types of seafood required different extracting and analytical methods. In this study, a universal microwave-assisted extraction was developed to extract each arsenic species including As(V), As(III), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB), arsenosugars and so on in various seafood with a extraction efficiency > 95% and without altering their original species, and a universal cation exchange IC-ICP-MS (ion chromatography-inductively coupled plasma mass spectrometry) method was developed for the detection of arsenic species in various seafood (seaweed, fish, shellfish and shrimp) with a method detection limit of 8.0 ng As/g dried seafood–12.0 ng As/g dried seafood. Especially, the extract of seafood obtained with our microwave-assisted extraction can be directly used for the following IC-ICP-MS detection without any additional pretreatment. By using the extraction method and IC-ICP-MS method, we have successfully detected each arsenic species including As(V), As(III), MMA, DMA, AsB, arsenosugars and so on in seaweed, fish, shellfish and shrimp samples with a recovery of 92%–104% and a relative standard deviation (RSD, n = 5) < 5%. The developed microwave-assisted extraction method and IC-ICP-MS detection method is simple, has broad applicability, high efficiency, excellent accuracy and strong resistibility to the complicated matrix, which promising a reliable approach for objectively and scientifically assessing arsenic health risks in various seafood to ensure the consumption safety of seafood.

Detection of trace metal ions in high-purity boric acid by online two-dimensional valve switching coupled with ion chromatography-inductively coupled plasma mass spectrometry

In this paper, a two-dimensional valve switching technique was established to detect 10 trace metal ions in high-purity boric acid by ion chromatography-inductively coupled plasma mass spectrometry (IC-ICPMS). The system consisted of a quantitative loop, a matrix capture column, an iminodiacetic acid cationic chelating column, an ion chromatography column, two sample valves and an inductively coupled plasma mass spectrometer. The iminodiacetic acid cationic chelating column coupled the metal ions in the sample with its carboxyl functional groups to separate them from the matrix boric acid solution, and then eluted the chelated metal ions into the ion chromatographic column and inductively coupled plasma mass spectrometer. The proposed method feasibly achieved an online, rapid and efficient detection of 10 trace ions in high-purity boric acid with the optimized experimental conditions (1.0 mol/L HNO3), such as loading solution, loading flow rate, type of eluent, concentration of the eluent, sample matrix, etc. The experimental data showed that this method had good linearity in the range of 0.01–2.0 μg/L for 10 metal ions, such as Cr, Fe, Ni, Co, V, Mn, Cu, Zn, Cd and Pb in high-purity boric acid samples, with a correlation coefficient greater than 0.998. The limit of detection (LOD, S/N = 3) and the limit of quantitation (LOQ, S/N = 10) were 0.001–0.023 μg/L and 0.003–0.077 μg/L, respectively. The relative standard deviation (RSD) of each element was less than 3.0% (n = 6) and the spiked recoveries ranged between 83% and 110%. This method could be proposed to be suitable for determination of trace metal ions in real samples.

Determination of trace inorganic antimony in PET-bottled soy sauce by ion chromatography-inductively coupled plasma mass spectrometry

In this work, a method for the determination of trace inorganic antimony in polyethylene terephthalate (PET)-bottled soy sauce by ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS) was developed. Trace inorganic Sb(III) has been discovered in PET-bottled soy sauce but has been difficult to directly quantify by using IC-ICP-MS. To determine trace inorganic Sb(III) in soy sauce, the sample was first filtered through a weak cation exchange solid-phase extraction (SPE) column and then subsequently washed with 3.0 mL of 0.02% l-ascorbic acid and 3.0 mL of methanol. Finally, the SPE column was eluted with 1.0 mL of 0.1% NaOH +2% H2O2. Under such conditions, the enriched inorganic Sb(III) in the SPE column converted into inorganic Sb(V) and was successfully eluted. Finally, the amount of inorganic Sb(V) in the eluate, equal to the amount of inorganic Sb(III) in the sample, was quantitatively analyzed by IC-ICP-MS. Thus, inorganic Sb(III) in soy sauce was detected. In the above method, the limit of detection (LOD) of inorganic Sb(III) was 0.1 μg L−1, and the linear correlation coefficient r was 0.995 when the calibration curve ranged from 0.5 μg L−1 to 5.0 μg L−1.The RSD (n = 6) was 8.8%, and the recoveries (n = 6) were 91%~97%. Comparing the amount of inorganic Sb(III) (0.8 μg L−1–2.3 μg L−1) with the total antimony (1.7 μg L−1–6.6 μg L−1), we found that 25.6% to 50.0% of the total antimony in soy sauce was inorganic Sb(III). In addition, spiked inorganic Sb(III) slowly converted into other forms of antimony in soy sauce over time, but that conversion was negligible within 10 min after spiking and did not affect the recovery experiment.

Manganese causes neurotoxic iron accumulation via translational repression of amyloid precursor protein and H-Ferritin.

For more than 150years, it is known that occupational overexposure of manganese (Mn) causes movement disorders resembling Parkinson's disease (PD) and PD-like syndromes. However, the mechanisms of Mn toxicity are still poorly understood. Here, we demonstrate that Mn dose- and time-dependently blocks the protein translation of amyloid precursor protein (APP) and heavy-chain Ferritin (H-Ferritin), both iron homeostatic proteins with neuroprotective features. APP and H-Ferritin are post-transcriptionally regulated by iron responsive proteins, which bind to homologous iron responsive elements (IREs) located in the 5'-untranslated regions (5'-UTRs) within their mRNA transcripts. Using reporter assays, we demonstrate that Mn exposure repressed the 5'-UTR-activity of APP and H-Ferritin, presumably via increased iron responsive proteins-iron responsive elements binding, ultimately blocking their protein translation. Using two specific Fe2+ -specific probes (RhoNox-1 and IP-1) and ion chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS), we show that loss of the protective axis of APP and H-Ferritin resulted in unchecked accumulation of redox-active ferrous iron (Fe2+ ) fueling neurotoxic oxidative stress. Enforced APP expression partially attenuated Mn-induced generation of cellular and lipid reactive oxygen species and neurotoxicity. Lastly, we could validate the Mn-mediated suppression of APP and H-Ferritin in two rodent invivo models (C57BL6/N mice and RjHan:SD rats) mimicking acute and chronic Mn exposure. Together, these results suggest that Mn-induced neurotoxicity is partly attributable to the translational inhibition of APP and H-Ferritin resulting in impaired iron metabolism and exacerbated neurotoxic oxidative stress. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.

Magnetic arginine-functionalized polypyrrole with improved and selective chromium(VI) ions removal from water

Magnetic arginine-functionalized polypyrrole (Fe3O4@Arg-PPy) nanocomposite was fabricated by in-situ polymerisation of pyrrole (Py) monomer in the presence of arginine and Fe3O4 nanoparticles for toxic chromium(VI) ions removal from simulated and chromium ores leaching effluent. The nanocomposite adsorbent was characterised using a variety of techniques, including, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS), high resolution-transmission electron microscopy (HR-TEM), vibration sample magnetometer (VSM), Braunauer-Emmett-Teller (BET) method and X-ray photoelectron spectroscopy (XPS). The adsorption kinetics study for the removal of Cr(VI) ions using Fe3O4@Arg-PPy demonstrated that the process followed a pseudo-second-order model. Isothermal investigation, on the other hand, revealed a monolayer adsorption behaviour following the Langmuir model with a maximum absorption capacity of 322.58 mg/g at 25 °C and pH 2. The plausible Cr(VI) adsorption mechanisms were inferred taking into consideration the presence of amino functional groups within Fe3O4@Arg-PPy moiety, the fates of chromium valence state, and the solution pH variation. Reduction of Cr(VI) to Cr(III) by active electron rich nanocomposite was established using ion chromatography-inductively coupled plasma-mass spectrometry (IC-ICP-MS) and XPS analyses. Cr(VI) removal took place via electrostatic attractions, reduction and chelation. Even in high salinity conditions, Fe3O4@Arg-PPy also retained its impressive adsorption efficiency towards Cr(VI) ions. Further, assessment for Cr(VI) ions removal in chromium ores leaching water samples demonstrated its potential practicability. The described adsorbent could equally be regenerated for four adsorption-desorption cycles, retaining up to 64% of its adsorption efficiency.

Chromium hazard and risk assessment: New insights from a detailed speciation study in a standard test medium.

Despite the consensus about the importance of chemical speciation in controlling the bioavailability and ecotoxicity of trace elements, detailed speciation studies during laboratory ecotoxicity testing remain scarce, contributing to uncertainty when extrapolating laboratory findings to real field situations in risk assessment. We characterized the speciation and ecotoxicological effects of chromium (CrIII and CrVI ) in the International Organization for Standardization (ISO) medium for algal ecotoxicity testing. Total and dissolved (< 0.22 μm) Cr concentrations showed little variability in media spiked with CrVI , whereas dissolved Cr concentration decreased by as much as 80% over a 72-h time period in medium amended with CrIII . Analyses by ion chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS) highlighted the absence of redox interconversion between CrIII or CrVI both in the presence and absence of algal cells (Raphidocelis subcapitata). Furthermore, the concentration of ionic CrIII dropped below detection limits in less than 2 h with the corresponding formation of carbonate complexes and Cr hydroxides. Precipitation of CrIII in the form of colloidal particles of variable diameters was confirmed by nanoparticle (NP) tracking analysis, single particle ICP-MS, and single particle counting. In terms of time-weighted dissolved (< 0.22 μm) Cr concentration, CrIII was 4 to 10 times more toxic than CrVI . However, CrIII ecotoxicity could arise from interactions between free ionic CrIII and algae at the beginning of the test, from the presence of Cr-bearing NPs, or from a combination of the 2. Future ecotoxicological studies must pay more attention to Cr speciation to reliably compare the ecotoxicity of CrIII and CrVI . Environ Toxicol Chem 2018;37:983-992. © 2017 SETAC.

Report of the CCQM-K124: trace elements and chromium speciation in drinking water—part A: trace elements in drinking water, part B: chromium speciation in drinking water

CCQM-K124 was organized by the Inorganic Analysis Working Group (IAWG) of CCQM to assess and document the capabilities of the national metrology institutes (NMIs) or the designated institutes (DIs) to measure the mass fractions of trace elements (As, B, Cd, Ca, Cr, Hg and Mo) and hexavalent chromium (Cr(VI)) in drinking water. The National Metrology Institute of Japan (NMIJ) and the Government Laboratory, Hong Kong SAR (GLHK) acted as the coordinating laboratories.This comparison is divided into two parts. Part A was organized by the NMIJ and the trace elements were the analytes, and Part B was organised by the GLHK and Cr(VI) was the analyte.In Part A, results were submitted by 14 NMIs and nine DIs. The participants used different measurement methods, though most of them used direct measurement using inductively coupled plasma-optical emission spectrometry (ICP-OES), inductively coupled plasma-mass spectrometry (ICP-MS), and isotope dilution technique with ICP-MS. The results of As, B, Cd, Ca and Cr show good agreement with the exception of some outliers. Concerning Hg, instability was observed when the sample was stored in the light. And some participants observed instability of Mo. Therefore, it was agreed to abandon the Hg and Mo analysis as this sample was not satisfactory for KC. In Part B, results were submitted by six NMIs and one DI. The methods applied were direct measurement using 1,5-diphenylcarbazide (DPC) derivatisation UV-visible spectrophotometry, standard addition using ion chromatography-UV-visible spectrophotometry or HPLC—inductively coupled plasma-mass spectrometry (ICP-MS) and isotope dilution technique with ion chromatography—ICP-MS. The results of all participants show good agreement.Accounting for relative expanded uncertainty, comparability of measurement results for each of As, B, Cd, Ca, Cr and Cr(VI) was successfully demonstrated by the participating NMIs or DIs.Main textTo 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).

Trivalent chromium solubility and its influence on quantification of hexavalent chromium in ambient particulate matter using EPA method 6800

Measurement of carcinogenic Cr(VI) in ambient PM is challenging due to potential errors associated with conversion between Cr(VI) (a carcinogen) and Cr(III) (an essential nutrient). Cr(III) conversion is a particular concern due to its >80% atomic abundance in total Cr. U.S. Environmental Protection Agency (EPA) method 6800 that uses water-soluble isotope spikes can be used to correct the interconversion. However, whether the enriched Cr(III) isotope spikes can adequately mimic the Cr(III) species originally in ambient PM is unknown. This study examined the water solubility of Cr(III) in ambient PM and discussed its influence on Cr(VI) measurement. Ambient PM10 samples were collected on Teflon filters at four sites in New Jersey that may have different Cr emission sources. The samples were ultrasonically extracted with 5 mL DI-H2O (pH 5.7) at room temperature for 40 min, and then analyzed by ion chromatography–inductively coupled plasma mass spectrometry (IC-ICPMS). Cr(III) was below detection limit (0.06 ng/m3) for all samples, suggesting water-soluble Cr(III) species, such as CrCl3, Cr(NO3)3, and amorphous Cr(OH)3, in the ambient PM were negligible. Therefore, the enriched 50Cr(III) isotope spike (in the form of Cr(NO3)3) could not mimic the original ambient Cr(III). Only the conversion of 53Cr(VI) (in the form of K2CrO4) was taken into account when correcting the interconversion. We then used NaHCO3-pretreated MCE filters (prespiked with enriched isotope species) to measure Cr(VI) in the ambient PM10. The samples were ultrasonically extracted at 60 C pH 9 solutions for 40 min followed by IC-ICPMS analysis. Due to the correction of Cr(VI) reduction, the Cr(VI) concentrations determined by EPA method 6800, 0.26 ± 0.16 (summer) and 0.16 ± 0.11(winter) ng/m3 (n = 64), were significantly greater than those by the external standard curve, 0.21 ± 0.17 (summer) and 0.10 ± 0.07 (winter) ng/m3 (n = 56) (p < 0.01, Student’s t-test). Our study revealed that appropriate application of EPA method 6800 is important because it only applies to soluble fraction of Cr species in ambient PM.ImplicationsAccurate measurement of carcinogenic Cr(VI) in ambient PM is challenging due to conversion between Cr(VI) (a human carcinogen) and Cr(III) (a human essential nutrient). The conversion of Cr(III) is of particular concern due to its dominant presence in total Cr (>80%). This study examined the water solubility of Cr(III) in ambient PM that was collected at four locations in New Jersey. Then we discussed the influence of Cr(III) solubility on the application of EPA method 6800, which utilizes enriched isotope spikes to correct the interconversion. Our results suggested that appropriate application of EPA method 6800 is important because it only applies to soluble fraction of Cr species.

Optimization and validation of strategies for quantifying chromium species in soil based on speciated isotope dilution mass spectrometry with mass balance

Strategies were designed to quantify hexavalent (Cr(VI)), soluble trivalent (Cr(III)) and insoluble chromium (Cr) species in soil by integrating existing methods of Cr(VI) and total Cr determination with speciated isotope dilution mass spectrometry (SIDMS, EPA Method 6800). Two different extraction methods that utilize a NaOH–Na2CO3 solution (EPA Method 3060A) and alkaline solution of ethylenediaminetetraacetic acid (EDTA) were used to extract Cr(VI) (along with soluble Cr(III) in the latter case). The extracted Cr was speciated by ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS), and the separated species were quantified using the mathematical relationships in SIDMS with simultaneous correction for their method-induced transformations. The Cr species that fell out as insoluble solid during extraction were determined by isotope dilution mass spectrometry (IDMS) after decomposing the extraction residues in a mixture of mineral acids according to EPA Method 3052. Several certified reference materials and a soil sample were analyzed using the proposed strategies. The measured mass fractions of Cr(VI) and total Cr in the reference materials statistically agreed with the certified values at 95% CL. The insoluble fraction of Cr accounted for 64–107% of the total Cr in the samples. The validity of the strategies was proved using mass balance by comparing the sum of the mass fractions of Cr(VI), soluble Cr(III) and insoluble Cr with the total Cr measured in the corresponding samples; the latter was determined by IDMS after decomposing the soils using EPA Method 3052 with single spiking.

Method development for the redox speciation analysis of iron by ion chromatography–inductively coupled plasma mass spectrometry and carryover assessment using isotopically labeled analyte analogues

An ion chromatography–inductively coupled plasma mass spectrometry (IC-ICP-MS) method was developed for the redox speciation analysis of iron (Fe) based on in-column complexation of Fe2+ and Fe3+ by dipicolinic acid (DPA). The effects of column type, mobile phase composition and molecular ion interference were studied in the method optimization. The carryover of the target species in the IC-ICP-MS method was uniquely and effectively evaluated using isotopically enriched analogues of the analytes (54Fe2+ and 57Fe3+). Standard solutions of the enriched standards were injected into the system following analysis of a sample, and the ratios of the isotopes of iron in the enriched standards were calculated based on the chromatographic peak areas. The concentrations of the analytes carried over from the sample to the enriched standards were determined using the quantitative relationship in isotope dilution mass spectrometry (IDMS). In contrast to the routine way of evaluating carryover effect by injecting a blank solution after sample analysis, the use of isotopically enriched standards identified significant analyte carryover in the present method. Extensive experiments were carried out to systematically identify the source of the carryover and to eliminate the problem; the separation column was found to be the exclusive source. More than 95% of the analyte carryover was eliminated by reducing the length of the column. The detection limit of the IC-ICP-MS method (MDL) for the iron species was 2ngg-1. The method was used to determine Fe2+ and Fe3+ in synthetic aqueous standard solutions and a beverage sample.

Behavior of hexavalent chromium in the water supply system by IC-ICP-MS method

The analysis conditions for measuring trace concentration of Cr(VI) based on the ion chromatography-inductively coupled plasma-mass spectrometry (IC-ICP-MS) method was examined. By optimizing the analysis conditions, the measurement of 0.02 μg-Cr(VI)/L was achieved with a high degree of accuracy. The behavior of Cr(VI) through the water treatment process in Osaka city was investigated and it was determined that there was a tendency that the Cr(VI) concentration slightly fluctuated throughout the water treatment process with the highest concentration being observed in finished water. The Cr(VI) concentration at the outlet of Kunijima purification plant was less than 0.02–0.13 μg/L, while water taps where retention time from the plant was 4–15 h, were less than 0.02–0.10 μg/L. Also, it was found that Cr(III) was oxidized to Cr(VI) by sodium hypochlorite and ozone being used in the water treatment process. Based on this finding, the oxidation reaction of Cr(III) to Cr(VI) was examined. When sodium hypochlorite was added to granular activated carbon (GAC)-treated water and purified water containing Cr(III), the oxidation of Cr(III) to Cr(VI) proceeded and the Cr(VI) production in GAC-treated water was relatively higher. In addition, it was determined that the Cr(III) oxidation reaction rate depended on water temperature and it was faster when the water temperature was higher.